Surgery With Answers

Assessment Exam for USMLE Step 2: Surgery *

Answers and Explanations

*USMLE is a joint program of the Federation of State Medical Boards of the United States, Inc. and the National Board of Medical Examiners.

©2003 Kaplan, Inc. All rights reserved. No part of this book may be reproduced in any form, by photostat, microfilm, xerography or any other means, or incorporated into any information retrieval system, electronic or mechanical, without the written permission of Kaplan, Inc. Not for resale.

Surgery Assessment Exam 1.

A 67-year-old man with a 50 pack-year history of smoking has been having persistent cough for about 6 months and shortness of breath for the past three weeks. A chest x-ray shows a right pleural effusion, which obscures the x-ray image of the lung itself. A pleural tap is performed, retrieving 1000 cc of bloody fluid. Repeat chest x-ray shows a 6-cm round opacity in the midfield of the right lung. Cytology shows the bloody pleural fluid to be a malignant effusion, consistent with a diagnosis of squamous cell carcinoma of the lung. The patient is most anxious that “something be done” and is willing to undertake any available treatment. Which of the following is the most appropriate next step in management? (A) (B) (C) (D) (E)

CT scan of the mediastinum Cervical mediastinal exploration Palliative chemotherapy and radiation Palliative pneumonectomy Pulmonary function studies

2.

A 58-year-old man complains of fatigue and weight loss. He has been “healthy all his life” and does not have a history of alcohol abuse. When first examined, a faint trace of jaundice is detected in his sclera. Laboratory determinations show a total bilirubin of 4, alkaline phosphatase of 700 U/L, and transaminases (AST) of 60 U/L. Sonogram of the right upper abdomen shows dilated intrahepatic and extrahepatic biliary ducts, and a large, distended, thin-walled gallbladder, without stones. Except for the dilated biliary structures, CT scan is unremarkable. An ERCP shows extrinsic compression of both the intrapancreatic portion of the common duct and the pancreatic duct, with proximal dilatation of both structures. Which of the following is the most likely diagnosis? (A) (B) (C) (D) (E)

Carcinoma of the ampulla of Vater Carcinoma of the head of the pancreas Cholangiocarcinoma Chronic pancreatitis Hepatitis

1

USMLE Step 2 Assessment Exam

3.

A 48-year-old woman with terminal liver failure due to chronic hepatitis C receives a cadaveric liver transplant. She is given only the right lobe of the transplanted organ (the left lobe was assigned to a pediatric patient also on the waiting list). Five days after the transplant, she begins to show laboratory signs of decreased liver function, and by the sixth day her transaminases exceed 3000 U/L. CT scan shows the transplanted organ to be swollen, with gas in the tissues. The pediatric patient who received the other lobe of the same liver is doing fine. Which of the following studies is most likely to provide a diagnosis?

5.

(A) Doppler color flow ultrasound of the hepatic artery and portal vein (B) Liver biopsy looking for acute rejection (C) Serology looking for reactivation of hepatitis C (D) Sonogram of the biliary tree (E) Tissue typing and cross-match looking for preformed antibodies

(A) (B) (C) (D) (E)

6. 4.

A 19-year-old man is stabbed in the right chest. He arrives at the emergency department short of breath, pale, diaphoretic, and anxious. His neck and forehead veins are visibly bulging. Initial evaluation shows a blood pressure of 75/45 mm Hg and a feeble pulse of 110/min. The right side of his chest does not have breath sounds, and it is tympanitic to percussion. Palpation at the base of the neck shows tracheal deviation to the left. Which of the following is the most important next step in management? (A) Emergency blood gases (B) Emergency chest x-ray (C) Insertion of a large-bore needle into the right pleural space (D) Intravenous infusion of Ringer’s lactate (E) Oxygen administration by face mask

A 66-year-old woman was riding in the right front seat of a car that crashed against an overpass abutment. Three other occupants of the vehicle died at the scene. She was wearing a seat belt, and appeared not to be seriously injured when extricated from the wreck. She arrives at the emergency department fully conscious, with stable vital signs. There is a severe bruise going from her right shoulder to her left hip, marking the imprint left by the seat belt. X-rays show fractures of the right clavicle, right first and second ribs, sternum, and left iliac crest. Chest x-ray shows a wide mediastinum. Which of the following is the most appropriate next diagnostic study? Aortogram Diagnostic peritoneal lavage Spiral CT scan of the chest Ultrasound of the abdominal cavity Ultrasound of the pericardial sac

On the morning after an abdominal surgical exploration for blunt trauma, a 23-year-old man develops renal failure and acute respiratory distress. He had been severely kicked in the abdomen during a robbery attempt, and at surgery he was found to have multiple liver and splenic lacerations, approximately 2 liters of blood in the peritoneal cavity, and a large retroperitoneal hematoma. The operation lasted 4 hours and it included repair of liver lacerations, splenectomy after an unsuccessful attempt at splenic repair, retroperitoneal exploration, and removal of the tail of the pancreas. He received 10 liters of Ringer’s lactate and 8 units of blood during the procedure. At this time he has a very tense and distended abdomen, and the retention sutures used for his abdominal closure are cutting through the very tight tissues of his abdominal wall. Which of the following is the most likely cause of his current problems? (A) Abdominal compartment syndrome (B) Acute renal failure caused by hemoglobinemia and hemoglobinuria (C) Adult respiratory distress syndrome (D) Fat embolism (E) Intraabdominal bleeding

2

Surgery

7.

A 44-year-old man suffers second- and third-degree burns to both of his arms when he is splashed by boiling radiator fluid upon removing the radiator cap in his car to find out why the engine was running hot. He seeks medical help 3 days after the accident. The total extent of the burns is estimated to add up to 8% of body surface, and he does not have circumferential burns. The burned areas are surrounded by erythema and he has mild fever. After thorough cleansing of the burned areas, which of the following is the most appropriate next step in management? (A) (B) (C) (D) (E)

8.

Apply wet to dry dressings Perform bilateral escharotomies Treat with mafenide acetate Treat with silver sulfadiazine Treat with triple antibiotic ointment

A lanky, gangly, 14-year-old boy has had right knee pain for several weeks. He has also noticed that he has been limping when he walks. He has no history of trauma. On physical examination, there is no knee swelling, tenderness, or limitation to the range of motion of the knee. His right hip has limited motion, and as the hip is flexed, the thigh goes into external rotation and cannot be internally rotated. Which of the following is the most likely diagnosis? (A) (B) (C) (D) (E)

9.

Avascular necrosis of the capital femoral epiphysis Developmental dysplasia of the hip Posterior dislocation of the hip Septic hip Slipped capital femoral epiphysis

A 44-year-old man is bitten by a snake while on a hunting trip. The bite is just above his right ankle. His fellow hunters apply a tourniquet just above the knee, and they all undertake the long journey back to their hometown. The patient is seen in the emergency department 4 hours after the bite took place. The tissues around the bite mark are not tender, swollen, or discolored, and his vital signs are normal, but the leg has no palpable pulses and is pale below what is obviously a very tight tourniquet. On releasing the constricting device, the lower extremity regains pulses and becomes reddish in color. Two hours later, the patient complains of severe pain in the calf. He still has palpable pulses in the foot, but his leg muscles are very tense, tender, and hard to palpation, and passive motion of his toes elicits excruciating pain. Which of the following is the most appropriate next step in management? (A) (B) (C) (D) (E)

10.

Elevation of the leg and systemic diuretics Emergency fasciotomy Hyperbaric oxygen Polyvalent snake antivenin X-rays of the foot and lower leg

A 62-year-old woman describes a peculiar problem with her right hand. Once or twice a week, she will wake up in the middle of the night with the middle finger acutely flexed, and she is unable to extend it. The only way she can get it back in normal position is to pull it with her other hand. The finger then “snaps” into place, but it does so in a very painful manner. The problem has been present for several months and the episodes are happening with greater frequency. She is afraid that surgery might be recommended and wants to avoid that option. Which of the following is the best therapy at this time? (A) (B) (C) (D) (E)

Nonsteroidal anti-inflammatory agents Physical therapy Splinting in extension during the night Steroid injections to the tendon sheath Surgery is the only option

3

USMLE Step 2 Assessment Exam

11.

A 45-year-old woman is on total parenteral nutrition (2 liters per day) for a high output fistula of the duodenum that developed 7 days after surgery for a duodenal diverticulum. In the past 2 days, her daily total parenteral nutrition intake was increased from 2500 to 3500 ml of a solution of 25% dextrose with 4% amino acids. She is also receiving 2 liters per day of Ringer’s lactate through a separate line. Her daily urinary output went up from 1500 ml to 2800 ml to 4200 ml over the past 3 days. In the last 24 hours, she became lethargic and went into a coma. The latest laboratory studies show a blood sugar of 800 mg/dL and a serum sodium concentration of 155 mEq/L. Which of the following is the most likely explanation for her present situation? (A) (B) (C) (D)

Developed brain edema Developed high-output renal failure Developed osmotic diuresis and lost water Hasn’t received enough calories to maintain brain function (E) Received too much sodium in her intravenous fluids

12.

A 66-year-old man has had symptomatic gastroesophageal reflux disease for many years. Last year he had an endoscopy and biopsies that revealed severe peptic esophagitis with severe dysplastic changes. He was advised to have surgery, but he refused. Approximately 2 months ago he developed dysphagia for solids, and this has gradually progressed to include dysphagia for soft foods, and more recently for liquids. He has lost 20 pounds. Which of the following is the most likely diagnosis? (A) (B) (C) (D) (E)

4

Achalasia Adenocarcinoma of the esophagus Barrett esophagus Squamous cell carcinoma of the esophagus Stricture or ulceration

13.

A 7-year-old boy has a bloody bowel movement. He is otherwise asymptomatic. His parents bring him for evaluation within 1 hour of the event. Physical examination is unremarkable. Gastric aspiration produces clear greenish fluid. Rectal and anal examination is positive for occult blood in the stool, but is otherwise normal. His hemoglobin is 14 g/dL. Which of the following is the most appropriate next diagnostic study? (A) (B) (C) (D) (E)

14.

Arteriogram Colonoscopy Radioactively labeled technetium scan Tagged red cell scan Upper gastrointestinal endoscopy

A 41-year-old man complains of soiling of his underwear. About 6 months ago he had an ischiorectal abscess drained, but he still has occasional anal discomfort. His temperature is 36.7 C (98.0 F). Physical examination shows several openings in the skin lateral to the anus, approximately 1 to 3 cm from the anus. Brownish, malodorous fluid can be expressed from openings. Rectal examination allows palpation of a cordlike thickening of the tissue going from the skin openings toward the lumen of the anal canal. Which of the following is the most appropriate treatment for this problem? (A) (B) (C) (D) (E)

Fistulotomy Incision and drainage Lateral internal sphincterotomy Long-term antibiotics Marsupialization

Surgery

15.

16.

A 20-year-old college student suffers from episodes of convulsions and coma that occur early in the mornings when he goes jogging before having breakfast. He was seen by a nurse practitioner at the student health service, but no studies were performed. He was labeled with a diagnosis of adult onset epilepsy, and was given medications that have not eliminated his neurologic symptoms. Then, one of his attacks occurs near a medical center and he is taken there while still unconscious. At that time his blood sugar is found to be 38 mg/dL. He wakes up promptly when an ampule of 50% dextrose is administered intravenously. Subsequent studies show high levels of insulin and C-peptide in his blood. Which of the following is the most appropriate next diagnostic study?

17.

(A) (B) (C) (D) (E)

18.

CT scan of both adrenals CT scan of the pancreas Comprehensive psychiatric evaluation MRI of the brain MRI of the pituitary gland

The parents of a 12-year-old girl are interested in sending her to a summer camp that offers a program of strenuous physical exercise. They are specifically interested in this type of program because the girl has been “puny” all her life, is always catching colds, and “needs to develop her strength.” A careful physical examination done before enrollment shows that she has a faint pulmonary flow systolic murmur and a fixed split-second heart sound. Chest x-ray shows increased pulmonary vascular markings. She is denied admission to the camp. Which of the following is the most appropriate next step in management?

A 59-year-old man with a 40 pack-year history of smoking has a chest x-ray performed because of a persistent productive cough. The film shows a 2-cm coin lesion in the upper lobe of the right lung. Which of the following is the most appropriate next step in management? (A) Order bronchoscopy and biopsies (B) Order sputum cultures (C) Order sputum cytology and CT scan of the chest and upper abdomen (D) Perform a transthoracic needle biopsy of the mass (E) Try to locate an older x-ray that could be compared with this one

A 6-year-old boy is brought to the physician because of a swelling at the base of his neck. Physical examination reveals a mushy, round, 6-cm mass occupying the entire left supraclavicular area. The skin can be easily moved over the mass, but the mass itself cannot be easily displaced from where it is, and palpation suggests that only the top of it is being felt. The mass is not tender and the child is otherwise asymptomatic. Which of the following is the most appropriate next step in management? (A) (B) (C) (D) (E)

Arteriogram CT scan of the neck and chest Needle biopsy Radioactive iodine scan Surgical resection

(A) Cardiac catheterization (B) Development of a program of less strenuous physical exercise (C) Diuretics and sodium restriction until her pulmonary congestion clears up (D) Echocardiography (E) Sputum cultures and appropriate antibiotic therapy

5

USMLE Step 2 Assessment Exam

19.

A 72-year-old man develops acute abdominal pain of sudden onset. He is brought to the emergency department within 30 minutes from the onset of the pain. He describes the pain as diffusely periumbilical, constant, and extremely severe, and indeed his appearance is that of someone in great distress. However, the physical examination of his abdomen shows only very mild tenderness and seems to be out of proportion with the severity of his pain. Other findings include a grossly irregular pulse of 105/min and 4+ occult blood in the stool. He is afebrile and has a leukocyte count of 9800/mm3. Chest x-ray and plain x-rays of the abdomen are noncontributory. Further diagnostic studies should focus on establishing which of the following?

21.

(A) (B) (C) (D) (E)

(A) (B) (C) (D)

Evidence of retroperitoneal bleeding The patency of his colonic lumen The patency of his coronary vessels The presence of perforation in his gastrointestinal tract (E) The status of the mesenteric circulation 22. 20.

A 45-year-old man has had chronic ulcerative colitis for 12 years. In the past 2 years he has required five hospitalizations to control flare-ups, and he is currently on high-dose steroids to prevent further exacerbations of the disease. He has lost 15 pounds in the past year, and at best he has at least eight or ten loose bowel movements per day. Colonoscopy shows extensive disease throughout the colon, but there is no evidence of carcinoma or dysplastic change. He accepts a recommendation to have surgery. Which of the following is the indicated procedure? (A) (B) (C) (D) (E)

6

Diverting colostomy Diverting ileostomy Ileotransverse colostomy Total colectomy with ileoproctostomy Total proctocolectomy

An 8-year-old boy is involved in an automobile accident. He was riding in the back seat and was wearing a seat belt. When evaluated in the emergency department he complains of mild abdominal tenderness, particularly on the left upper quadrant. He does not have guarding or rebound. His vital signs are stable, as is his hematocrit. A CT scan of the abdomen shows the presence of a small amount of blood free in the peritoneal cavity. The study also shows fractures of the ninth and tenth ribs on the left, and a laceration in the spleen. The laceration is 1.5 cm deep, and it does not involve trabecular vessels. Which of the following is the most appropriate next step in management? Arteriogram and embolization Bedrest and close in-hospital observation Discharge home Exploratory laparotomy and splenectomy Exploratory laparotomy and splenorrhaphy

A 66-year-old obese woman has a 5-day history of protracted vomiting, progressive abdominal distention, and no passage of stool or flatus. She had colicky abdominal pain for the first 3 days, but now has only vague generalized abdominal discomfort. She looks dehydrated and sick, and has a temperature of 38.1 C (100.6 F). Because of her size, physical examination of the abdomen is difficult. However, she is distended and a little tender, has no bowel sounds, and has no abdominal scars. The most impressive finding is pain to deep palpation over her right groin and femoral area, although her obesity precludes any certainty as to whether she has a palpable mass in that area. X-rays show multiple distended loops of small bowel, with air fluid levels. There is no gas in the colon. Which of the following is the most likely diagnosis? (A) (B) (C) (D) (E)

Adhesions causing intestinal obstruction Deep femoral venous thrombophlebitis Gallstone ileus Necrotic inguinal lymph nodes Richter incarcerated right femoral hernia

Surgery

23.

A 12-year-old boy has been complaining of pain in the middle of his right leg for the past 2 months. In the past 3 weeks, he has also noticed swelling over the same area, right around the middle part of the tibia. He describes episodes of subjective fever (never documented), but gives no history of trauma to the area. On physical examination, he has enlarged inguinal nodes on the right side, and he has a diffuse, tender swelling that involves most of the shaft of his right tibia. X-rays show a pathologic process that involves almost the entire shaft of the tibia, with areas of lytic destruction and multiple areas with concentric layers of reactive bone formation. Which of the following is the most appropriate next step in management? (A) Blood cultures and prolonged course of appropriate intravenous antibiotics (B) Immobilization in a plaster cast (C) Incision and drainage (D) Incisional biopsy under local anesthesia (E) Referral to an orthopedic oncologist for biopsy

24.

On the fourth postoperative day after a gastrectomy for cancer, a 73-year-old man complains of severe chest pain of sudden onset. He is short of breath, perspiring, and tachycardic. His neck veins are not distended, and auscultation of his chest is unremarkable. A 12-lead electrocardiogram shows occasional premature ventricular contractions, but there is no elevation of the ST segment. CK-MB enzyme levels are normal, and there are high levels of Troponin-T. Blood gases show PO2 of 94 mm Hg and PCO2 of 42 mm Hg. Which of the following is the most likely explanation for the pain? (A) (B) (C) (D) (E)

Anxiety Fat embolism Myocardial infarction Pulmonary embolus Tension pneumothorax

25.

During a prenatal sonogram at 18 weeks’ gestation, the presence of polyhydramnios is discovered, and further imaging demonstrates that the fetus has a very large diaphragmatic hernia on the left side. Calculations done by the radiologist and the neonatologist indicate that the fetus can be expected to be born with severe pulmonary hypoplasia. Given this finding, which of the following is the most appropriate management? (A) Arrange for the delivery to take place where Extracorporeal Membrane Oxygenation (ECMO) is available (B) Be prepared to surgically close the defect as soon as the infant is born (C) Induce labor at the end of the seventh month of pregnancy (D) Perform prenatal, fetal surgery to close the defect (E) Terminate the pregnancy

26.

A 75-year-old man complains of episodes of violent coughing that wake him up at night. He has been having these for more than a year and they are becoming more frequent. When pressed for details, he explains that when he wakes up he is “choking” and that fragments of undigested food come up when he coughs and tries to “clear up” his tracheobronchial tree. From time to time he also finds bits of undigested but putrid food on his pillow when he wakes up in the morning. Lately he also has had occasional dysphagia, which he locates to the lower neck. Which of the following is the most appropriate diagnostic study? (A) Barium swallow (B) Bronchoscopy (C) Esophageal manometry (D) Esophageal x-rays with water-soluble contrast material (E) Upper gastrointestinal endoscopy

7

USMLE Step 2 Assessment Exam

27.

A 24-year-old woman is extricated from a wrecked car and brought to the emergency department by helicopter. She is the only survivor of four occupants in a car that crashed against a bridge abutment. She is conscious but moaning with pain, which she locates to her abdomen. She is also cold, pale, shivering, anxious, and thirsty. Her blood pressure is 75/55 mm Hg, with a feeble pulse of 130/min. Quick evaluation in the emergency department shows abdominal tenderness and abdominal distention, with no signs of pelvic fracture or femur fractures. She has no signs of rib fractures, and has bilateral breath sounds. Both arms have multiple closed fractures, and she also has facial lacerations. A central venous line is placed and reads a central venous pressure of zero. Which of the following is the most likely reason for her state of shock? (A) (B) (C) (D) (E)

28.

Intraabdominal bleeding Intracranial bleeding Neurogenic shock Pericardial tamponade Tension pneumothorax

A 53-year-old man is hit in the head with a golf ball during a golf game. He drops to the ground, and his friends who rush to his aid find him to be unconscious and breathing loudly (like snoring) but otherwise unhurt. By the time help is summoned and a cart arrives to take him to the clubhouse, he has awakened, and he refuses any further attention. In fact, he resumes his game and finishes with a pretty good score. He goes to the dressing room to take a shower and promises to join his fellow players for dinner. When he does not show up after 45 minutes, his friends go looking for him. They find him unconscious in the locker room, and it is obvious to them that he has a large dilated pupil on the right side and a normal pupil on the left. A CT scan of this man’s head would most likely show which of the following? (A) Biconvex, lens-shaped hematoma on the left (B) Biconvex, lens-shaped hematoma on the right (C) Diffuse blurring of the gray-white matter with multiple punctate hemorrhages (D) Semilunar hematoma on the left (E) Semilunar hematoma on the right

8

29.

A 19-year-old man is stabbed in the right chest with a 5-cm switchblade. He arrives at the hospital short of breath, with a blood pressure of 95/70 mm Hg and a pulse of 100/min. The entrance wound is just lateral to the right nipple, right under the lower edge of the fifth rib. He has no breath sounds on the right hemithorax, which sounds dull to percussion. Chest x-ray shows diffuse opacity over the entire right hemithorax. A chest tube placed on the right recovers 1200 cc of bright red blood, and drains another 250 cc over the ensuing 10 minutes. He is taken to the operating room for prompt thoracotomy. The surgeons should expect to find that which of the following is the source of bleeding? (A) (B) (C) (D) (E)

30.

An intercostal vessel The lung parenchyma The right ventricle The skin and subcutaneous tissue The thoracic aorta

A 62-year-old man has been involved in a major accident where the car in which he was riding crashed head-on against oncoming traffic. As the initial assessment is made in the emergency department, it is obvious that he has a pelvic fracture as well as fractures in his right lower leg. His vital signs are stable. When a lab technician asks him to produce a urine sample for the lab, the patient tries but is unable to void. The technician then requests one of the attending trauma surgeons to catheterize the patient to get the necessary urine sample. It is then discovered that he has blood at the meatus, as well as a significant scrotal and perineal hematoma. Which of the following is the most appropriate next step in management? (A) Bladder catheterization to obtain the necessary urine sample (B) External fixation of the pelvic fracture (C) Nephrostomy tube to gain access to his urinary tract (D) Retrograde cystogram via Foley catheter (E) Retrograde urethrogram

Surgery

31.

A 3-year-old child is brought in by his stepmother, who relates that he carelessly burned himself while playing with hot water in the kitchen. The child looks withdrawn, with a flat affect, and he is much smaller than would be expected for his age. He has second-degree burns in both buttocks, with blisters and erythema but no overt signs of infection. Which of the following is the most important element in treating this child?

34.

(A) Debridement of the burned areas in the operating room (B) Liberal application of silver sulfadiazine to the burns (C) Referral to the proper authorities, on suspicion of child abuse (D) Systemic antibiotics (E) Use of mafenide acetate for topical antibacterial therapy

32.

A 4-year-old girl is outside her house in the early morning hours, waiting while the whole family loads up the minivan that is going to take them on a long-anticipated vacation. A skunk suddenly appears out of the bushes, and the fascinated little girl chases it into a corner. The skunk releases its pungent urine, but when cornered, it also inflicts a deep bite into the girl’s hand. In the ensuing commotion the animal escapes. In addition to cleansing of the wound and tetanus prophylaxis, the little girl will need which of the following? (A) Careful observation for development of signs and symptoms suggestive of rabies (B) Rabies immunoglobulin (C) Rabies immunoglobulin and rabies vaccine (D) Rabies vaccine (E) Systemic antibiotics

33.

A 22-year-old man falls on his outstretched hand and comes in complaining of pain in the wrist. On physical examination he has distinct, severe tenderness to palpation over the anatomic snuffbox. X-rays are read as negative. Which of the following is the most likely diagnosis? (A) (B) (C) (D) (E)

A 46-year-old man complains of severe back and leg pain of sudden onset, triggered when he attempted to lift a heavy object. The pain feels like “electricity shooting down his leg” and is made much worse by sneezing, coughing, or straining. He is unable to walk because of the pain, and he lies on the stretcher with the affected leg flexed. The most impressive finding on physical exam is excruciating pain when the straight-leg raising test is done, but it is also noted that he has a distended bladder, flaccid rectal sphincter, and perineal saddle area anesthesia. Resolution of this problem will best be achieved by which of the following? (A) (B) (C) (D) (E)

35.

Emergency surgical decompression Manipulation of the lumbar spine Skeletal traction Spinal tap Three weeks of bed rest

On the third postoperative day after a total colectomy for chronic ulcerative colitis, the patient’s urinary output drops to about 15 to 20 cc per hour. The urine looks deep yellow, with no blood in it. The patient weighs 65 kg, and during the first two postoperative days was producing 50 to 75 cc of urine per hour. There is an indwelling Foley catheter in the urinary bladder, and it has been repeatedly ascertained that the catheter is draining freely. The patient has a blood pressure of 110/60 mm Hg and a pulse of 95/min. A urine sample is sent to the laboratory for a urinary sodium concentration determination. The lab reports that the urine contains 15 mEq of sodium per liter. Which of the following is the most likely problem? (A) (B) (C) (D) (E)

Acute renal failure Hypernatremia Hyponatremia Insufficient fluid administration Surgical injury to the ureters

Avascular necrosis of the radial head Carpal tunnel syndrome Compartment syndrome De Quervain tenosynovitis Undisplaced fracture of the scaphoid (carpal navicular) bone

9

USMLE Step 2 Assessment Exam

36.

A 23-year-old man was involved in a motorcycle accident in which his perineum was crushed. Ever since that event, he has been impotent. He does not have nocturnal erections, and cannot achieve erections for masturbation or for intercourse. At the time of the accident he did not have urethral or bladder injuries, and he did not fracture his pelvis or his corpora cavernosa. Which of the following is the most likely reason for his problem? (A) (B) (C) (D) (E)

37.

10

Erectile nerve plexus injury Psychogenic impotence Testicular atrophy Vascular arterial injury Venous insufficiency

A 23-year-old man is found to have a 7-cm, solid testicular mass. He indicates that he noticed the mass only about 3 weeks ago but that it was only 2 or 3 cm in diameter, at the most. He was hoping that it would go away but obviously it did not. Workup shows pulmonary metastasis on both lungs, as well as liver metastasis. After appropriate surgery is done, additional treatment for this young man will be primarily based on which of the following? (A) (B) (C) (D) (E)

38.

Antiandrogen medications Immunotherapy with BCG Platinum-based chemotherapy Radiation therapy to affected areas Tamoxifen

A urologist gets a phone call at 11 P.M. Very apologetic parents indicate that their 17-year-old son is having severe colicky flank pain and complaining of dysuria. In response to a direct question, they indicate that indeed the young man had gone out drinking beer with his friends, and that he had never committed such a transgression before. This patient is most likely suffering from which of the following conditions? (A) (B) (C) (D) (E)

39.

Low implanted ureter Posterior urethral valves Ureteral stone Ureteropelvic junction (UPJ) obstruction Vesico-ureteral reflux

A 24-year-old man comes to the emergency department complaining of excruciating testicular pain of sudden onset. He has swollen scrotal contents on the left, fever, pyuria, and very tender testicle and cord on the affected side. The testis is in the normal position. A tentative diagnosis of acute epididymitis is made, but before he is started on antibiotics, it would be prudent to do which of the following? (A) (B) (C) (D) (E)

Aspiration of scrotal contents for culture CT scan looking for ureteral stones Color flow Doppler ultrasound Trans-scrotal biopsy Workup to rule out urinary tract obstruction

Surgery

40.

A 45-year-old man develops hypertension, diabetes, headaches, and sweaty hands. When he is seen at the clinic, it is obvious that he has a big jaw; big, thick lips; a large tongue; and broad, spadelike hands. When asked about it, he indicates that he now wears larger shoes than he used to, and he says he had to stop wearing his wedding band because he had trouble getting it on or off his finger. Workup should include determining the levels of which of the following? (A) (B) (C) (D) (E)

41.

42.

5-Hydroxy-indoleacetic acid Somatomedin C Steroid breakdown products Thyrotropin Vanillylmandelic acid (VMA)

A 72-year-old man suddenly develops aphasia and hemiparesis, without a headache. He is brought to the emergency department within 20 minutes of the onset of the problem. He is taken rapidly to the CT scanner, where it is determined that he has a small area of ischemia in the brain, corresponding to the location of the affected functions. There is no radiologic evidence of intracranial bleeding. By the time he returns from the CT scan, 50 minutes have elapsed since the onset of his symptoms. His neurologic deficits have not resolved. Which of the following is the most appropriate next step in management? (A) Careful observation for possible spontaneous resolution (B) Duplex scanning of the carotid vessels (C) Emergency carotid endarterectomy (D) Emergency craniotomy and resection of affected area (E) Intravenous infusion of tissue-type plasminogen activator

A 23-year-old woman has been complaining of severe headaches for 3 months. The headaches are worse in the mornings, and she locates them to the center of her skull, behind the root of the nose. In the past 3 weeks she has also noted blurred vision, and 2 days ago she began to vomit without apparent reason. She says the vomiting occurs with no effort whatsoever and that “the stuff just comes out and hits the wall.” Her diagnosis will best be made with which of the following diagnostic studies? (A) (B) (C) (D) (E)

43.

Magnetic resonance imaging (MRI) of the head Mapping of the visual fields Sonogram of the head Spinal tap Upper GI endoscopy

A 44-year-old woman with diabetes is being treated with antibiotics for ethmoid sinusitis. She was asked to return for a follow-up visit, and when she does, it is noted that she has developed strabismus. Her right eye is not moving along with the left, and the right pupil is not reacting to light. She also has exophthalmos, papilledema, and high fever. She confirms that ever since she woke up this morning she has been seeing double, and that she has a persistent headache. Which of the following is the most likely diagnosis? (A) (B) (C) (D) (E)

Brain tumor Cavernous sinus thrombosis Central retinal artery occlusion Intracranial bleeding Optic nerve neuritis

11

USMLE Step 2 Assessment Exam

44.

A 1-year-old boy is brought to the physician for a wellbaby visit. It is noted that the boy’s left pupil is white, whereas the right one is black. The mother indicates that the change is of recent origin, perhaps a week at the most, and that the boy does not seem to be affected by whatever is going on. Cursory examination with the ophthalmoscope suggests not that the white originates from the lens but that the color is from the retina itself. The physician should proceed on the assumption that this is which of the following? (A) (B) (C) (D) (E)

45.

A normal variant of no particular significance Early vitiligo Fungal infection Glaucoma Retinoblastoma

A homeless man in his late fifties comes repeatedly to the emergency department requesting medication for pain. He complains of constant epigastric pain that radiates straight through to his back, which he says he has had for years. Sometimes the pain is more bearable but at times it is so severe that he has to seek help. He is a reluctant patient who does not trust doctors or hospitals, and he is very reticent about providing a medical history. Many times he has smelled strongly of alcohol when he shows up. Only once did he consent to have some tests done; they demonstrated diabetes, steatorrhea, and calcifications throughout his pancreas on plain film of the abdomen. His amylase and lipase serum and urinary values were normal. He has no gallstones. Which of the following is the most likely diagnosis? (A) (B) (C) (D) (E)

46.

Abdominal aortic aneurysm Cancer of the pancreas Chronic pancreatitis Episodes of acute alcoholic pancreatitis Pancreatic pseudocyst

A 33-year-old woman complains of bloody nipple discharge. Her physical examination is completely normal, but at times blood can indeed be expressed from the breast by vigorous palpation. This problem has been present for about 2 or 3 years, and the woman is tired of throwing away perfectly good underwear because of the bloodstains. She has never been pregnant and has no family history of breast cancer. She has never had a mammogram done. One is scheduled for her, but she begs to have an honest disclosure of the presumed diagnosis. The diagnosis is probably which of the following? (A) (B) (C) (D) (E)

47.

Breast cancer Cystosarcoma phyllodes Fibroadenoma Fibrocystic disease Intraductal papilloma

A 72-year-old woman had a lumpectomy and axillary sampling (sentinel node biopsy) for a very small peripheral breast mass that had been diagnosed as cancer by fine-needle aspiration (FNA). The final pathology report indicates that the tumor measures 1 cm, has ample clear margins, is infiltrating ductal carcinoma, is estrogen- and progesterone-receptor positive, and has an axillary lymph node metastasis identified in the sampled sentinel node. Clinically, by palpation alone, the axilla had been assumed to be negative for metastasis. There is no evidence of distant metastasis, either, and the tumor is classified as T1, N1, M0. The patient is very anxious not to have chemotherapy, because a friend of hers who did lost all her hair and vomited severely during the therapy. Which of the following is the most appropriate reassurance for this patient? (A) Axillary dissection will take care of the problem (B) Conversion to a total mastectomy is a good alternative (C) Radiation therapy will take care of any remaining disease (D) She does not need systemic therapy of any kind (E) She is a good candidate for Tamoxifen

12

Surgery

48.

A 27-year-old woman is found to be hypertensive. In fact, she has rather recalcitrant hypertension that does not respond well to the usual medical therapy. Her physicians suspect that she may have “more than meets the eye” and therefore conduct a rather extensive workup. Her serum electrolytes are normal, her urinary catecholamines are not elevated, she has increased levels of aldosterone and renin (both modestly elevated), she has normal urinary levels of steroid metabolites, she has a normal chest x-ray, and she is just as hypertensive in the legs as she is in the arms. Two of the attending physicians swear that they can hear a faint upper abdominal bruit, and a third thinks there is a right flank murmur. Which of the following additional tests would make sense in this setting? (A) (B) (C) (D) (E)

49.

50.

A 72-year-old hypertensive African American complains of very severe chest pain of sudden onset. He arrives at the emergency department diaphoretic, tachycardic, and somewhat out of breath. Except for a blood pressure of 220/110 mm Hg, physical examination is unremarkable. Chest x-ray shows a wide mediastinum. Electrocardiogram is normal, and troponin levels are not elevated. Which of the following is the most appropriate next diagnostic study? (A) (B) (C) (D) (E)

Blood gases Creatine phosphokinase-MB (CPK-MB) Gastrografin swallow Spiral CT scan of the chest Ventilation-perfusion scan

Duplex scanning of the renal vessels Fasting test MRI of the adrenal glands MRI of the pituitary Spiral CT scan of the chest

A full-term, newborn boy has green vomiting. Flat and upright x-rays are performed. The babygrams show a large air-fluid level in the stomach and a smaller one in the first portion of the duodenum. There is also gas in the distal bowel loops, with a normal pattern. Barium enema shows the entire colon to be on the left side, rather than in its normal configuration. Which of the following is the most appropriate therapy? (A) (B) (C) (D) (E)

Broad-spectrum antibiotics Diverting colostomy Emergency surgical correction Gastrografin enema Nasogastric tube and parenteral nutrition

13

Surgery Assessment Exam Answers and Explanations ANSWER KEY 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25.

C B A C C A D E B D C B C A B D E B E E B E E C A

26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50.

A A B A E C C E A D D C D C B E A B E C E E A C D

15

USMLE Step 2 Assessment Exam

1.

2.

3.

16

The correct answer is C. The presence of malignant pleural effusion makes cancer of the lung inoperable. The only available therapy is radiation and chemotherapy, which cannot be expected to be curative. CT scan of the mediastinum (choice A) and the more aggressive cervical mediastinal exploration (choice B) are steps meant to elucidate the presence or absence of mediastinal metastatic nodes in order to determine operability. The presence of malignant pleural effusion has already established that the tumor is inoperable. There is no such thing as a palliative pneumonectomy (choice D). In the treatment of lung cancer, such an operation is undertaken only when there is hope of cure. Pulmonary function studies (choice E) are often part of the workup of patients with cancer of the lung when the available evidence suggests that the tumor is not yet widespread, but there is concern that limited pulmonary function may preclude the possibility of removing the affected lung. That is not the situation here. The correct answer is B. The extrinsic compression of both the common and pancreatic ducts is indicative of the presence of a tumor arising from the head of the pancreas, a tumor that is still too small to be detected in the CT scan. Cancer of the ampulla of Vater (choice A) would have been diagnosed by the endoscopy that was done in order to perform the ERCP. Cholangiocarcinoma (choice C) would give an applecore image in the common duct, with no abnormalities in the pancreatic duct. Chronic pancreatitis (choice D) would be very rare in a patient who has neither pre-existing biliary disease nor a history of alcohol abuse. In this case there is no mention of abdominal pain either, or of diabetes or steatorrhea. The laboratory picture of jaundice due to hepatitis (choice E) includes very high transaminases and only modest elevation of the alkaline phosphatase. Furthermore, in hepatitis there is no dilation of the biliary tree. The correct answer is A. Technical problems are always the first guess when liver transplants go bad. Very high transaminases suggest cellular death, which gas in the tissues confirms. Vascular compromise is the most likely problem. Acute rejection (choice B) can happen, but it is less likely this early on. Hepatitis C (choice C) can recur and destroy the transplanted liver, but it does so much later.

The biliary tree can be obstructed or it can necrose if the arterial supply is compromised, but the pattern here is not one of biliary obstruction (high alkaline phosphatase, near-normal transaminases), and thus a sonogram of the structure (choice D) is not the best bet. Preformed antibodies (choice E) very rarely kill transplanted livers. The liver is amazingly resistant to such a fate, even when preformed antibodies exist. 4.

The correct answer is C. The clinical picture is that of tension pneumothorax, with significant compromise of ventricular filling. Immediate decompression of the pleural space will bring instant relief to the cardiovascular problem. Insertion of a chest tube should follow the initial decompression with a needle. Diagnostic tests, either blood gases (choice A) or x-rays (choice B), are not necessary when the clinical diagnosis is so clear, and they delay the necessary emergency treatment. X-rays will follow after the chest tube has been inserted. Intravenous fluids (choice D) will be helpful since the form of cardiogenic shock present in this case is extrinsic because of compression of the blood inflow into the heart. Given a choice as to what will help the most, however, there is no question that decompressing the pleural space is the most urgent and helpful step. Thus, Ringer’s lactate is not the best answer. Oxygen (choice E) is also helpful, but as was the case with choice D, it is not the magic bullet that will instantly improve the situation.

5.

The correct answer is C. The obvious concern is traumatic transection of the aorta that can occur with severe deceleration injuries, can be asymptomatic, and is suggested by the wide mediastinum. The first diagnostic test in that setting is the spiral CT scan, which is noninvasive and often sufficient to establish the diagnosis. Aortogram (choice A) would have been the correct answer several years ago, before the spiral CT scan was developed. At the present time, that invasive study is indicated in a case like this only if the CT fails to establish a diagnosis. We have no evidence at this time that there is occult bleeding (she is hemodynamically stable); thus, doing a diagnostic peritoneal lavage (choice B) or an ultrasound of the abdomen (choice D) is not going to add valuable information. Furthermore, were she to develop signs of intraabdominal bleeding, a CT scan might be a better option if she is not literally “bleeding to death.” Ultrasound of the pericardial sac (choice E) is valuable when pericardial tamponade is suspected, but we have

Surgery Answers and Explanations

no reason here to think about it. She is not in shock, and she does not have the telltale distended veins that suggest extrinsic compression around the heart. 6.

7.

8.

The correct answer is A. We have to postulate a single explanation for two simultaneous complications: renal failure and respiratory distress. A very tight abdomen with abdominal compartment syndrome will produce both. The physical examination indicates the presence of a tight abdomen, and the circumstances preceding the complication are perfect for its development: a long operation with multiple transfusions and the need for aggressive intravenous fluid administration. Hemoglobinemia and hemoglobinuria (choice B) can produce renal failure, not respiratory failure. The setting would have been that of crushing injuries with lots of dead muscle. The adult respiratory distress syndrome (choice C) can produce respiratory failure, but not renal failure. The usual setting would be a prolonged postoperative course with sepsis and multiple complications. A fat embolism (choice D) will produce respiratory distress, but not renal failure. The usual setting would be a patient with multiple long bone fractures. Intraabdominal bleeding (choice E) can produce a distended and tense abdomen and it might lead to renal failure, but the main finding would be hypovolemic shock. The correct answer is D. Silver sulfadiazine is the standard “work horse” for topical antimicrobial care of burns. Wet to dry dressings (choice A) are a time-honored way to keep granulation tissue clean, but it does not offer the antimicrobial protection that burns need. Escharotomies (choice B) are needed for circumferential burns that are interfering with the blood supply of the extremity. That problem is usually manifest within the first 24 hours after a burn, and the burn has to be all around the circumference of the extremity to act as a tourniquet. Mafenide acetate (choice C) is used when deep penetration is required. Otherwise, it is painful and can lead to complications (metabolic acidosis). Triple antibiotic ointment (choice E) is reserved for burns around the eyes (where silver sulfadiazine can be very irritating). The correct answer is E. Slipped capital femoral epiphysis occurs in this age group in boys who are either chubby or lanky. The physical findings described are characteristic.

Avascular necrosis of the capital femoral epiphysis (choice A) is seen at the age of approximately 6 years. Developmental dysplasia (choice B) is typically diagnosed at the time of birth or shortly thereafter. Posterior dislocation (choice C) is a traumatic lesion, seen when the thigh is driven backwards, as occurs when a patient strikes the dashboard with his knees during an automobile crash. Septic hip (choice D) is seen in young children who have had a febrile illness and then seem to be in pain and refuse to move a hip. 9.

The correct answer is B. The physical findings are classic for compartment syndrome. The culprit was not the snake but the patient’s well-intentioned fellow hunters, who subjected his leg to prolonged ischemia. Prolonged ischemia, followed by reperfusion, is one of the common causes for a compartment syndrome. The lower leg and the forearm are particularly vulnerable. Nothing short of fasciotomy will save the muscles of the leg from avascular necrosis. Elevation and diuretics (choice A) will not do it. Hyperbaric oxygen (choice C) has a role to play in the treatment of gas gangrene. It will not save muscles that are swollen under tight fascial boundaries. Snake antivenin (choice D) is not what he needs. If the venom had been the problem, he would have had local signs of envenomation (pain, swelling, and discoloration) at the bite site, and systemic signs also. Please note that we have no description of the snake, and thus no certainty that it was a poisonous species. Even when they are poisonous, up to 30% of cases may have no envenomation with the bite. X-rays (choice E) are not needed to diagnose a compartment syndrome.

10.

The correct answer is D. Steroid injections are the first line of therapy for trigger finger, which is the problem described in this vignette. Neither anti-inflammatory agents (choice A) nor physical therapy (choice B) will provide significant relief. Splinting the finger so it cannot flex (choice C) seems intuitively appealing. Immobilization of fingers in a nonfunctional position, however, is not a good idea. Furthermore, the problem itself would not be alleviated by simply preventing the finger from flexing. Surgery may be needed, but it is not the first (or only) line of therapy, as suggested in choice E.

17

USMLE Step 2 Assessment Exam

11.

12.

13.

18

The correct answer is C. A higher than normal concentration of serum sodium usually means that the patient has lost water. In this case, we have a clear reason why that would have occured: she has been unable to metabolize the high amounts of glucose that she is getting, the glucose has “piled up in the blood,” and osmotic diuresis has ensued. Brain edema (choice A) is the opposite of what she has. Her brain cells are shrunken as a result of water loss. High-output renal failure (choice B) need not be invoked to account for the understandable development of osmotic diuresis. The kidneys are responding to the high osmolar load in the glomerular filtrate (caused by sugar) that decreases the osmotic gradient that normally pulls water out of the distal tubule in response to antidiuretic hormone. In other words, what is happening here is a physiologic response that does not indicate the presence of renal disease. She is receiving 3500 calories per day. She obviously cannot use them well (she needs more insulin), but that is not the reason for the brain dysfunction (choice D). The rapidly developing hypertonicity is the culprit. A high level of serum sodium concentration usually means water loss rather than sodium gain (choice E). She is receiving 2 liters of Ringer’s lactate, which matches quite well the volume and sodium content of her duodenal fistula. She is not getting too much sodium. The correct answer is B. The natural progression of severe dysplasia secondary to gastroesophageal reflux disease is the development of adenocarcinoma. The pattern of progressive dysphagia is classic. Achalasia (choice A) can also produce dysphagia, but frequently it is worse for liquids than for solids. The patient is usually a young or middle-aged woman, and reflux does not play a role. Barrett esophagus (choice C) is a predecessor of dysplasia, not a sequel to it. Squamous cell carcinoma of the esophagus (choice D) is seen in older men with a long history of smoking and drinking. Reflux, on the other hand, produces adenocarcinoma. He could have stricture or ulceration (choice E), but he would need an awful lot of luck to have that as the explanation for his dysphagia. The sequela one expects after severe dysplasia is adenocarcinoma. The correct answer is C. In this age group Meckel diverticulum leads the list of causes for gastrointestinal bleeding. The scan should be able to identify the gastric mucosa in the diverticulum that is responsible for the bleeding.

Arteriogram (choice A) is wrong on many accounts: expensive, invasive, and unlikely to be diagnostic if the bleeding is not massive (more than 2 mL/min or a situation that requires a blood transfusion every 4 hours to keep normal vital signs and normal hemoglobin). Colonoscopy (choice B) would be good for an older person with unexplained anemia and occult blood in the stool. In that setting a cancer of the cecum is the likeliest diagnosis. In this child, the study is likely to be negative. Tagged red cell scan (choice D) is considered by many the first test to be done when gastrointestinal bleeding is not coming from the upper tract (negative gastric aspirate). It will not be helpful unless there is significant bleeding at the time. It might be a good way to begin the workup in an adult, but in a child of this age the betting should begin with Meckel diverticulum. Upper gastrointestinal endoscopy (choice E) is unlikely to be helpful when the gastric aspirate is clear. 14.

The correct answer is A. The condition described is fistula in ano, for which the treatment is unroofing of the tract. To do so, the surgeon cuts open the fistula and resects the roof of it, leaving an open ditch to fill with granulation tissue. The procedure is called fistulotomy. Incision and drainage (choice B) is needed when there is an undrained abscess. Lateral internal sphincterotomy (choice C) is used to lower sphincter tone and thus treat anal fissures. Antibiotics (choice D) will not get rid of an epithelialized tract that connects the anal canal with the skin. Marsupialization (choice E) is used for the treatment of pilonidal cysts.

15.

The correct answer is B. The man has an insulinoma. He has the attacks when he is fasting, at which time his blood sugar is low, and his symptoms respond to glucose administration (Whipple’s triad). Furthermore, he has high levels of insulin and C-peptide (his insulin is endogenous). A CT scan is needed to look for the tumor. The adrenals (choice A) are not the source of the problem. If his C-peptide had been low, we would have needed psychiatric evaluation (choice C). High insulin levels with low C-peptide levels identify the person who is self-administering insulin for secondary gain. He is having convulsions, but a brain tumor (choice D) is not the likely culprit. Besides the fact we have a ready explanation for his neurologic symptoms, people with brain tumors typically have a history of several months of persistent, constant headaches and other manifestations of increased intracranial pressure.

Surgery Answers and Explanations

Arteriogram (choice A) is an expensive and invasive study that is only done when vascular anatomy must be delineated in detail. It has no indication for what we expect to be a lymphoid mass. Needle biopsy (choice C) will not establish the extent of this mass. If done with a large-bore core biopsy instrument, protracted drainage of lymph is likely to ensue. Tissue diagnosis is not necessary in this case, because the odds heavily favor a benign congenital anomaly. Radioactive iodine scan (choice D) is used when thyroid tissue has to be identified. It would have been a good answer for an anterior mediastinal mass that could be a substernal goiter. The picture presented in this question is not suggestive of thyroid disease. Surgical resection (choice E) will eventually be done, but it would be foolish to undertake that action not knowing how far the dissection will have to go. Proper position of the incision (or incisions) has to be planned in advance.

Insulinomas are in the pancreas, not the pituitary (choice E). They function independently and are not driven by the pituitary. 16.

The correct answer is D. The clinical presentation is classic for atrial septal defect. An echocardiogram will establish the diagnosis in a noninvasive way. Surgical correction should follow. Cardiac catheterization (choice A) would have been the correct answer many years ago, when noninvasive diagnostic modalities had not yet been developed. Today, catheterization is very rarely needed for the diagnosis of congenital heart defects. Choice B ignores the obvious diagnosis that an astute clinician should instantly recognize. Neglect of the rightto-left shunt that this girl has will lead to the development of pulmonary hypertension and eventually irreversible damage to the pulmonary circulation. In a way, the same dire ultimate outcome will ensue if we treat this as a temporary problem of fluid overload (choice C), or a lung infection (choice E), because both of these ignore the real diagnosis.

17.

The correct answer is E. Obviously, the concern is cancer of the lung, and the odds (based on age and history of smoking) are that he has it. But the workup of lung cancer is expensive and invasive, and it could be obviated if an x-ray taken 1 or 2 years earlier shows the same mass. If earlier films do not exist (or show no mass), some of the other answers are correct, depending on the circumstances. Bronchoscopy and biopsy (choice A) are the correct answer for central lesions that could not be diagnosed with less invasive studies. Sputum culture (choice B) is not correct unless cancer has been ruled out. If the older x-ray were to show that the same coin lesion was there 2 years ago, then it represents a granuloma or a benign mass. Cultures might explain why he now has persistent productive cough. Sputum cytology and CT scan (choice C) are a good noninvasive way to begin a workup once choice E has been executed. If we get lucky, the cytology might give the diagnosis (luck is needed; this is a low-yield test), and the CT might establish the extent. Transthoracic biopsy (choice D) is the invasive way to go for the peripheral lesions.

18.

The correct answer is B. The most likely diagnosis is cystic hygroma. These masses of lymphoid tissue often extend deep into the chest, and it is imperative to know the full extent of the anomaly before resection is attempted. The CT scan will provide that information.

19.

The correct answer is E. The combination of atrial fibrillation and sudden onset of abdominal pain should suggest mesenteric embolization. The presence of blood in the lumen of the gut provides additional evidence. This patient is lucky in being evaluated at a very early stage of the disease, when the pain is still due to the ischemia and not yet to the subsequent development of peritonitis. If the latter supervenes, due to dead bowel, his mortality after exploratory laparotomy will be very high. But if the mesenteric occlusion is demonstrated and the bowel is revascularized, he has a much better prognosis. Nothing in the presentation suggests retroperitoneal bleeding (choice A). If he had back pain and a palpable pulsatile mass, that would be a very good choice. Nothing suggests colonic occlusion (choice B), either. X-ray evidence of dilated colon, perhaps with the classic parrot’s beak of a sigmoid volvulus, would justify this approach. Coronary occlusion (choice C) can indeed masquerade as abdominal pain, and the paucity of physical findings might seem to be confirmatory evidence. But that would not explain the blood in the lumen, and it would ignore the powerful clue provided by the atrial fibrillation. If his gastrointestinal tract were perforated (choice D) he should have a rip-roaring acute abdomen, and probably free air in the x-ray films as well.

20.

The correct answer is E. The only curative operation for ulcerative colitis is total proctocolectomy, either with a permanent ileostomy or a fancy ileoanal anastomosis with creation of an ileal pouch. The rectum is always involved in the disease, and if it is not removed, recurrence is guaranteed.

19

USMLE Step 2 Assessment Exam

diagnostic biopsy. As pointed out, however, that invasive step should not be undertaken by those who are not qualified to proceed with treatment, thus making choice D also inappropriate.

All other suggested procedures in choices A, B, C and D fail to remove the rectum, and are therefore inadequate. 21.

22.

23.

The correct answer is B. Nonoperative management of splenic injuries is the treatment of choice in hemodynamically stable children. The exact protocol will vary among institutions, but they all include close in-hospital observation for at least a few days and initial bedrest. Restricted activities usually follow hospital discharge. Sending the patient home (choice C) would be risky. He is stable now, but he sustained significant injury and he could bleed later. Choices A (arteriogram and embolization), E (exploratory laparotomy and splenorrhaphy), and D (exploratory laparotomy and splenectomy) are too aggressive and are not justified at the present time. The correct answer is E. This patient clearly has a picture of intestinal obstruction, and within a 5-day time frame bowel sounds (and colicky pain) are no longer present. Had she had prior surgery (and a scar to prove it), adhesions would have been the best bet. In the absence of such background, hernia becomes the next possibility. In obese women, a Richter hernia in the femoral canal cannot be palpated, but the tenderness over the area provides the missing clue. Adhesions (choice A) require a history of prior surgery. Thrombophlebitis (choice B) could give groin pain but not intestinal obstruction. Gallstone ileus (choice C) is a sneaky cause of intestinal obstruction, but the x-ray should have shown air in the biliary tree and the right groin should not have been tender. Necrotic inguinal nodes (choice D) could give groin pain but not intestinal obstruction. The correct answer is E. This process could be a number of things, including infection, benign tumor, or malignant tumor, but our obligation under the circumstances is to rule out life-threatening conditions. Ewing sarcoma is the deadly tumor that comes to mind with this description. It has to be ruled out or confirmed, and the biopsy should not interfere with eventual surgical management if it proves to be malignant; thus, it should be done by whomever is eventually going to treat the patient. Once we have established that a biopsy is essential, it becomes obvious that to assume infection or benign process is the wrong course of action. Neither antibiotics (choice A), immobilization (choice B), nor incision and drainage (choice C) should precede the necessary

20

24.

The correct answer is C. The two leading contenders for severe chest pain in the postoperative period are myocardial infarction and pulmonary embolus. Timing usually provides the first clue: myocardial ischemia happens in the first day or two, whereas pulmonary embolus usually occurs after 5 or 6 days. Unfortunately this man got the pain halfway in between; it could be either one. If his EKG and CK-MB had been diagnostic, the answer would have been myocardial infarction, but that is still the answer even without the help of those two: Troponin-T is highly specific, and it identifies myocardial infarction in the subset of patients whose EKG and other enzymes are not diagnostic. Never blame problems on anxiety (choice A) until organic causes have been ruled out. Fat embolism (choice B) gives hypoxemia, but no pain. The usual patient has had long bone fractures rather than gastric cancer. Pulmonary embolus (choice D) should have happened a little later, and findings should include distended veins and hypoxemia with hypocarbia. The main reason it is not pulmonary embolus, however, is that Troponin-T comes from the myocardium, not from the lungs. Tension pneumothorax (choice E) does not give chest pain, but rather a patient with acute respiratory distress who goes into shock as his mediastinum is shifted by the increased intrapleural pressure. Auscultation of the chest would provide the diagnosis.

25.

The correct answer is A. Infants born with congenital diaphragmatic hernias have an immature lung with the very high pulmonary vascular resistance typical of the fetal circulation. They need several days of intensive, sophisticated respiratory support, until they convert to the normal respiratory pattern. The best way to provide that support in severe cases is with ECMO. Early surgery (choice B) is precisely what cannot be done until the lung has matured. Adding the immaturity of preterm delivery (choice C) to the expected immaturity of the lung would simply compound the problem. Prenatal surgery (choice D) may become the correct answer in the future. After all, there is no better extracorporeal oxygenator than the normal placenta. When this question was written (late 2002), however, the procedure was still experimental and very risky.

Surgery Answers and Explanations

The mortality of infants who require ECMO for this problem is approximately 50%, but that high risk does not justify across-the-board termination of pregnancy (choice E). 26.

The correct answer is A. The presentation is classic for Zenker diverticulum. Barium swallow should be diagnostic. Although the food spills into the tracheobronchial tree, the intrinsic problem is not in the tracheobronchial tree, and thus bronchoscopy (choice B) is not indicated. The problem is not related to motility either, so manometry (choice C) will not help. If the history had been one of many years of dysphagia with eventual food regurgitation, achalasia would have been a good bet and manometry would be part of the workup (after barium swallow). If one were suspicious of perforation, the x-rays indeed should be done with water-soluble contrast material (choice D), but otherwise barium gives a much better picture. Endoscopy (choice E) is an absolute no-no! Inadvertent perforation of the diverticulum could easily occur.

27.

The correct answer is A. A trauma patient who is in shock, with a central venous pressure of zero, is bleeding somewhere. The physical examination strongly suggests that the location of her internal injuries is in the abdomen. Intracranial bleeding (choice B) cannot produce shock. There is not enough room inside the head for a liter and a half of blood (the usual amount of blood loss needed to produce shock) and a functioning brain. Neurogenic shock (choice C) is seen with high spinal cord transections. Blood pressure is low, but patients do not have the “cold, pale, sweating” appearance described here. Both pericardial tamponade and tension pneumothorax (choices D and E) show up with high central venous pressure. The latter would also show no breath sounds in the affected hemithorax.

28.

The correct answer is B. The clinical picture is that of an acute epidural hematoma, and the location of the pupillary dilation correlates in most cases with the location of the hematoma (right or left). Acute epidural hematomas have a biconvex, lens-shaped appearance. Choice A is incorrect because it places the hematoma on the left (which could happen in 10% of cases but would not be “the most likely”). Diffuse blurring (choice C) is seen with diffuse axonal injury in much more severe trauma.

Choices D and E depict the x-ray appearance of an acute subdural hematoma, which is seen with more severe trauma and would not be likely to have the completely normal lucid period that this man had. 29.

The correct answer is A. Even without considering the size of the weapon and the exact location of the wound, when surgical intervention is needed for a traumatic hemothorax we suspect that the offending vessel is a systemic one, and statistically the most likely source is an intercostal. If you add the size of the blade and the location of the wound, as described in this case, there should be little doubt that an intercostal artery is injured. The lung parenchyma (choice B) bleeds little and usually stops bleeding by itself. Neither the right ventricle (choice C) nor the thoracic aorta (choice E) could be reached by a 5-cm blade from the entrance wound described. Further, injuries of the right ventricle usually produce pericardial tamponade rather than hemothorax. The skin and subcutaneous tissue (choice D) are unlikely to bleed this much, and if they did, the blood would be out on the floor or soaking his shirt, not inside the pleural cavity.

30.

The correct answer is E. The constellation of findings is indicative of urethral injury, which is best diagnosed with a retrograde urethrogram. Placement of a Foley catheter, as suggested in choices A and D, is absolutely contraindicated. Such a maneuver could compound the existing injury. External fixation of a pelvic fracture (choice B) is often used to buy time and minimize bleeding when a patient is hemorrhaging from a pelvic fracture, a situation that is not occurring here. Thus, while eventually something will be done to deal with the broken bones, right now it is more urgent to determine the extent of his urologic injuries. A nephrostomy tube (choice C) can indeed gain access to the urinary tract and decompress it when needed, but such an invasive step is probably not needed here. Suprapubic access is easier when the problem is in the urethra. Nephrostomy may be required if there is a problem with the ureter.

31.

The correct answer is C. Scalding burns in children should always raise the potential issue of child abuse. Burns on both buttocks are typical for a child who was held by arms and legs and dipped into hot water, and are inconsistent with the story offered by the stepmother. Protection of this child is more important than the details of how to treat his second-degree burns.

21

USMLE Step 2 Assessment Exam

Debridement (choice A) is not needed for clean-looking second-degree burns. Focusing on this step ignores the more important issue of possible abuse. Silver sulfadiazine (choice B) is indeed what will be used here, but if that is all that is done, the child may eventually be killed by his abusive parents. Systemic antibiotics (choice D) are rarely needed in the treatment of burns. Mafenide acetate (choice E) is not the first choice for topical burn care, and it should be reserved for cases where deep penetration of the antibacterial agent is needed. 32.

33.

34.

22

The correct answer is C. Bites from wild animals are potential sources of rabies. If the animal is not available to be killed for histologic studies of the brain, full rabies prophylaxis must be administered to the patient. The treatment includes passive and active immunization. Waiting for rabies to develop, as suggested in choice A, is tantamount to a death sentence. There is no effective treatment for the fully developed disease. Immunoglobulin alone (choice B) or vaccine alone (choice D) is not sufficient. Antibiotics (choice E) will not prevent rabies The correct answer is E. The physical findings and the mechanism of injury are typical. If the fracture is undisplaced, x-rays are often read as negative. Avascular necrosis of the radial head (choice A) is rare in this setting, and does not show up this way. Carpal tunnel syndrome (choice B) is seen in people who make repetitive wrist motions and who complain of numbness and tingling over the distribution of the median nerve. Compartment syndrome (choice C) occurs frequently in the forearm, and the clinical picture is that of deep pain all over the affected muscles, with excruciating pain on passive extension. De Quervain tenosynovitis (choice D) affects young women; the pain is typically elicited on physical exam by having the patient hold her thumb inside a fist and forcibly causing ulnar deviation of the wrist. The correct answer is A. The man obviously has a herniated lumbar disk but he also has a cauda equina syndrome, which is a surgical emergency. Manipulation (choice B) has no role to play in this condition, and could aggravate it. Skeletal traction (choice C) is not the answer, either.

Spinal tap (choice D) is equally wrong. There is no role for it whatsoever in the treatment of a herniated lumbar disk. Bed rest (choice E) is the correct answer for herniated disks, provided the complication of a cauda equina syndrome is not present. 35.

The correct answer is D. The low concentration of sodium in the urine indicates that efficient kidneys are attempting to conserve sodium and water to increase the extracellular fluid volume. The patient needs more fluid. Acute renal failure (choice A) would also show up with oliguria, but the sodium concentration in the urine would be high (above 40 mEq/L). The clinical manifestations of hypernatremia or hyponatremia (choices B and C), if severe and of rapid onset, are central nervous system symptoms. Otherwise, the abnormality is asymptomatic. Urinary volume is not necessarily affected. Surgical injury to the ureters (choice E) would have been evident earlier, and if both had been tied off, the urinary output would have been zero.

36.

The correct answer is D. The usual genesis of impotence after perineal injuries is arterial disruption. The erectile nerves (choice A) are typically damaged during pelvic surgery, such as radical prostatectomy or abdominoperineal resection. Psychogenic impotence (choice B) has sudden onset but is usually not universal. Although intercourse may not be possible, nocturnal erections typically continue to occur. Testicular atrophy (choice C), if present, would produce impotence of gradual onset. We should add that such atrophy would be rare in this setting. Venous insufficiency (choice E) may follow fracture of the corpora cavernosa, which did not occur in this patient.

37.

The correct answer is C. Most testicular cancers (which this is) are very chemosensitive, and platinum-based agents are particularly effective. Antiandrogens (choice A) have a role in extensive prostatic cancer, if orchiectomy has been declined. Immunotherapy with BCG (choice B) is used extensively for bladder cancer. Radiation (choice D) has a role but remains a local weapon. If radiation alone is used, the systemic metastasis will not be eradicated. Tamoxifen (choice E) is used for breast cancer.

Surgery Answers and Explanations

38.

The correct answer is D. A congenital narrowing at the UPJ has existed since birth, but it did not become manifest until a severe diuretic challenge occurred. Low implanted ureter (choice A) is asymptomatic in boys. In girls it can lead to incontinence. Posterior urethral valves (choice B) lead to anuria at birth. Ureteral stone (choice C) is possible, of course, but the correlation with the first exposure to beer makes UPJ obstruction the classical bet. Vesico-ureteral reflux (choice E) produces colicky flank pain but is associated with voiding as well as fever and chills, and usually occurs in a child younger than this patient.

39.

The correct answer is C. The condition with which acute epididymitis can be confused is testicular torsion. The latter is a surgical emergency. It would be devastating to rely on antibiotic therapy, see no resolution of the problem, and end up with a dead testicle because a diagnosis of torsion was missed. Color flow Doppler ultrasound will establish such diagnosis, if present. Aspiration (choice A) is not needed. Epididymitis is sexually transmitted. The bug can be identified in the urine if needed. Ureteral stones (choice B) are not involved in the genesis of epididymitis. Trans-scrotal biopsies (choice D) should not be done. If there were a suspicion of cancer, orchiectomy by the inguinal route is recommended. This is not the clinical picture of cancer. Urinary tract obstruction (choice E) has to be ruled out when urinary tract infections are more severe than expected, or when they occur in unusual candidates. But epididymitis is not unusual, or in any way related to obstruction.

40.

The correct answer is B. Acromegaly is the obvious clinical picture. Growth hormone needs to be measured. 5-Hydroxy-indoleacetic acid (choice A) is used for the diagnosis of carcinoid syndrome. Steroids (choice C) are involved in Cushing. This man does not have a cushingoid appearance. Thyrotropin (choice D) is used to diagnose thyroid dysfunction, which would also change the patient’s appearance but not in the way described here. VMA (choice E) is a byproduct of catecholamines, elevated in patients who have a pheochromocytoma.

41.

The correct answer is E. This man has an ongoing ischemic stroke. It is of limited extent, he has no bleeding, and he is still within the preferred 90-minute time window for the use of clot-busters. Continued observation in the hope that this is an ongoing transient ischemic attack (choice A) risks wasting valuable time and precluding the use of clot-busters. Most transient ischemic attacks would have resolved by the time he reached the ER, or by the time he returned from the CT scan. Studying the carotid vessels (choice B) is indicated when there have been transient ischemic attacks, and carotid endarterectomy is considered as a way to prevent future stroke. Carotid endarterectomies (choice C) are done to prevent strokes, not to treat ongoing strokes. Clot-busters are preferred for that situation. Ischemic areas of the brain do not improve with resection (choice D).

42.

The correct answer is A. The presentation is perfect for a brain tumor. The best imaging modality for brain tumors is MRI. Pituitary tumors that impinge upon the chiasma will produce visual field defects, but relying on this study (choice B) ignores the fact that the tumor could be anywhere else in the patient’s head. Thus, chances are that the visual fields are normal. Sonogram (choice C) is great in many areas of the body but not for intracranial pathology. Spinal tap (choice D) is absolutely contraindicated. She has increased intracranial pressure. Herniation is a distinct hazard if the tap is done. Her vomiting is projectile, suggesting that the genesis is increased intracranial pressure. Looking into the stomach (choice E) will be a waste of time.

43.

The correct answer is B. The history of sinusitis followed by the present picture indicate retrograde spread of the infection to the cavernous sinus. Brain tumors (choice A) have a history of months of increasing headaches, with eventual development of signs of increased intracranial pressure. Fever is not part of the picture. Occlusion of the retinal artery (choice C) produces sudden-onset blindness in the affected eye. Intracranial bleeding (choice D) produces severe headache of sudden onset, with or without neurologic deficits but not accompanied by fever or preceded by sinusitis.

23

USMLE Step 2 Assessment Exam

Pathology of the optic nerve (choice E) does not result in diplopia. 44.

45.

46.

24

The correct answer is E. The baby needs to be seen by an ophthalmologist immediately. These tumors can grow very fast, spread backward through the optic nerve, and kill very quickly. Choice A would be tantamount to malpractice. Vitiligo (choice B) does not whiten the retina. Fungal infection (choice C) is not a safe assumption to make because it would not command the emergency attention required. Children with glaucoma (choice D) have big, shiny, beautiful eyes. The eyes are enlarged by the high pressure and have constant tearing, thus deceiving the unaware into seeing beauty in them. The correct answer is C. The whole constellation of findings is typical for chronic pancreatitis. Abdominal aortic aneurysm (choice A) would be asymptomatic until rupture is imminent. At that time severe back pain may occur, but within hours death from exsanguination would supervene. Cancer of the pancreas (choice B) could indeed give back pain, but it would not be present for many years. Death would have happened by now. Episodes of acute alcoholic pancreatitis (choice D) are indeed present in this man’s background, but his pancreas is burned up now, incapable of producing elevations of pancreatic enzymes. He is no longer having acute episodes. Pseudocyst (choice E) is another complication of pancreatitis (or pancreatic trauma). The time table is shorter (weeks, perhaps a few months at the most), and an epigastric mass is often the leading presenting sign. The correct answer is E. Intraductal papillomas bleed but they are not palpable because of their very tiny size. Breast cancer (choice A) has to be ruled out, and that is why she is going to have a mammogram and subsequently a retroareolar exploration to resect her papilloma, but cancer is not the most likely diagnosis at age 33. Cystosarcoma phyllodes (choice B) is a gigantic tumor seen in young women. With nothing palpable in the patient’s breast, this is not what we should be thinking of. Fibroadenoma (choice C) is less spectacular in size but still it is a palpable, rubbery, movable tumor seen in young women—not a source of bloody nipple discharge.

The age is right for fibrocystic disease (choice D) but the symptoms are wrong. The latter should include cyclical pain and cyclical masses but no blood from the nipple. 47.

The correct answer is E. Postmenopausal women who have very small primary tumors and are receptor positive can be treated with hormonal manipulations alone when they have axillary metastasis. The presence of those metastases indicates that these patients have systemic disease and require systemic therapy. The purpose of axillary sampling is diagnostic, and unless the axilla is chock-full of palpable metastasis, it has no therapeutic value. Axillary dissection (choice A) is not what this woman needs. Likewise, she will not be helped by removing the rest of her breast (choice B). She needs systemic—not local— therapy. This patient will indeed receive radiation (choice C), but that is for local control, not for systemic disease. This patient has positive nodes; she needs systemic therapy. Choice D is just plain wrong.

48.

The correct answer is A. The probable diagnosis is renovascular hypertension due to fibromuscular dysplasia. An aortogram might eventually be needed, particularly if the choice is made to treat the patient with angioplasty and stenting, but a noninvasive duplex scanning might be a good way to begin. Fasting tests (choice B) are used in the workup of insulinoma. We have no evidence of adrenal (choice C) or pituitary (choice D) disease. Yes, the patient’s aldosterone levels are up, but if the renin is also elevated, that does not indicate autonomous abnormal production of aldosterone. If we were suspecting coarctation of the aorta, CT scan (choice E) would be a good idea. You might have guessed that the audible bruits may have come from a narrow aorta, but keep in mind that the patient has no scalloping of her ribs and that she is hypertensive in the legs. This is not coarctation.

49.

The correct answer is C. The diagnosis is malrotation. The duodenum is obstructed by Ladd bands, but the emergency is due to the fact that the entire small bowel is dangling from the mesenteric vessels, which could easily be twisted, resulting in bowel necrosis. Antibiotics (choice A) will not fix the baby’s bowel in a safe position, nor will colostomy (choice B). Further, he has duodenal obstruction, not rectal obstruction.

Surgery Answers and Explanations

Gastrografin enema (choice D) is used for meconium ileus. That condition includes a microcolon of disuse, but it is in the normal location. Nasogastric suction and parenteral nutrition (choice E) are used for necrotizing enterocolitis, which is seen in premature babies when they are first fed. That is not the case here. 50.

The correct answer is D. The hypertensive who seems to be having an MI but is not and whose mediastinum is wide has a dissecting aneurysm of the thoracic aorta. Spiral CT scan is indicated. Blood gases (choice A) will not hurt but they will not make the diagnosis. CPK-MB (choice B) is less useful than troponins. Do not keep pursuing the MI diagnosis; this patient does not have one. He does not have an esophageal perforation, either. He would have to have severe protracted vomiting or a recent upper GI endoscopy to get that. X-rays of the esophagus (choice C) will not help. Ventilation-perfusion scan (choice E) is the old way to pursue the diagnosis of pulmonary embolus. Spiral CT scan is now done in many centers, as a better test. So the correct answer will cover this diagnostic possibility as well.

25

BL3165A Printed in USA © 2003

kaplanmedical.com