USMLE WORLD ANSWERS

1. B. Isolated duodenal hematoma is treated conservatively with nasogastric tube and parenteral nutrition. This conservative approach has high cure rate and risk of surgery is avoided; however it is important to exclude other organ injury. IVF are not required as patient is hemodynamically stable; she needs nutrition until hematoma heals. Also, antibiotics are not indicated in this patient. She is afebrile and has no symptoms suggestive of infection. Surgery is needed only if there are other associated injuries or if the hematoma does not resolve w/in 2-3 wks w/ NGT and parenteral nutrition.

2. A.The patient presents with signs and symptoms suggestive of necrotizing surgical infection. The clues to the correct diagnosis include: (1) intensive pain in the wound accompanied by fever and tachycardia, (2) decreased sensitivity at the edges of the wound and (3) cloudy-gray discharge. Diabetes is an important predisposing condition. The necrotizing surgical infection is usually caused by mixed gram-positive and gram-negative flora. The presence of crepitus raises the suspicion that clostridial infection may be present, bu some streptococcal and other gas-forming organisms may also produce local crepitus. The treatment of necrotizing surgical infection is complex. The most important step in the management of this condition is early surgical exploration to assess the extent of the process and debride the necrotized tissues. Antibiotics are also important, but S. aureus is a less frequent pathogen causing this condition. General measures should include adequate hydration and glycemic control (choice D), but surgical exploration is more urgent. The discharge should be cultured (choice C), although the results are delayed. Observation (Choice E) is not appropriate, because the process spreads very quickly and is life threatening.

3. D.The child was involved in trauma and later d/ced. He later presents with a deviated mediastinum and mass in left lower chest. He has no fever or chills except for chest pain. One diagnosis, which is frequently missed in the ER, is traumatic rupture of the diaphragm. The rupture may be small or large and is usually on the left side, as the liver protects the right side. The diagnosis of diaphragmatic rupture is difficult and generally most individuals present later. Delayed presentation carries a high morbidity. Barium swallow will be diagnostic. All diaphragmatic ruptures require treatment. Surgery is best done via the abdomen in acute conditions and via the chest in chronic conditions. VATS would be diagnostic of diaphragmatic perforation on intial admission.

Option A: The patient has a collection/mass in the L. chest and it may look similar to pleural effusion. Placing a chest tuve in a pt w/ diaphragmatic perforation with bowel herniation can be a disaster, when in doubt, get a CT scan.

4. B.Major veins at the base of the neck have negative pressure during inspiration and, if injured at that moment, will suck air rather than bleed. The air embolism then leads to sudden death. Arterial injury (choice A) would have led to massive bleeding but not to sudden death.Pneumothorax (choice C) can indeed happen when surgery is being done in the supraclavicula area, and a sucking sound might even be heard. However, sudden lung collapse in a young, healthy person leads to dyspnea, not to sudden death. Sympathetic discharge (choice D) would be hard to produce while pulling and dissection a node. If it were done, however, there would be vasoconstriction, tachycardia, perspiration and hypertension.Essentially nothing would have happened at the time had the trachea (choice E) been injured.

5. CThe patient most likely has an injury to a major bronchus. In addition to the wretching effect of a sudden deceleration, these can happen when a major blow to the chest occurs at a time when the glottis is closed. If not recognized right away by the presence of subcutaneous emphysema, they become evident once the air leak persists and the lung does not re-expand. Air embolism (choice A) is manifested by sudden death shortly after a patient with unrecognized injuries to the tracheobronchial tree in proximity to major intrathoracic vessels is placed on a respirator.Injured lung parenchyma (choice B) can indeed leak air and produce a pneumothorax, but typically heals rapidly. Suction applied to a chest tube (choice D) is used to accelerate the rate of resolution of a pneumothorax, but the large amount of air draining in this case indicates that the pleural space fills as quickly as it can be drained out.

6. C.Intramural calcification of the gallbladder (aka porcelain gallbladder) is associated with a 20% risk for progression to gallbladder carcinoma. When the condition is discovered incidentally, usually a calcified mass on an abdominal xray, prophylactice cholecystectomy is recommended to reduce the risk for progression to malignancy. As the gallbladder wall is usually thick and fibrotic, it is usually necessary to perform an open cholecystectomy rather than a laparoscopic procedure. In any case, a biopsy of the gallbladder wall (choice A) is not recquired.

Medical treatment with ursodeoxycholic acid (choice B) is used to treat gallstones in poor surgical candiddates and is a mainstay of treatment for primary biliary cirrhosis.Gallbladder is a highly fatal malignancy so waiting for it to show up on CT (choice E) is very risky as operative mortality associated with cholecystectomies is low.

7. E.5 or more units of blood transfusion in a period of 24 hours is considered an indication for surgery.Both ligation and meso-caval shunt (choices C,D) have a high mortality rate in emergency settings. Ligation will no control the ascites, which in this patient is refractory to concervative treatment.TIPS (choice E) has a lower mortality rate. If successful, it will decrease the variceal and portal hydrostatic pressure and hence will decrease the bleeding and ascites. Hepatic encephalopathy is the main risk after the procedure.Sengstaken-Blakemore tube can stay in up to 48 hours with relatively low risk for esophageal ischemia and perforation. Choice A could be the correct answer if patient had recquired less than 5 units of blood.

8. B.Oxalate stones are due to excessive GI absorption of oxalate. Hyperoxaluria occurs in patients with SBR, inflammatory bowel disease and other malabsorptive states. The increased intestinal fat binds dietary calcium, which is then unavailable to bind oxalate as usual. Therefore, increased oxalate absorption in large bowel (unabsorbed bile salts may aid this) occurs and precipitates in kidney. Increased oxalate occurs in people who drink large amounts of tea, coffee, beer, chocolate and ethylene glycol overdose.Choice A: calcium stones associated with conditions causing hypercalciuria such as sarcoidosis, immobilization, Cushing syndrome and RTA. Treatment is to increase fluid intake and use of thiazide diuretics (NOT lasix).Choice C: struvite stones form in the collecting system and become infected with urea splitting organisms. Conditions required for formation of struvite stones are high urine pH, magnesium, ammonium and carbonate levels.Choice E: cysteine stones are rare and occur as part of an inherited disorder of defective renal transport. Stone formation begins in childhood and are a rare cause of staghorn calculi.

9. D.The woman is having clear signs of peritoneal irritation, immediately after the onset of pain. Most likely, a peptic ulcer has perforate and highly irritating stomach or duodenal contents have spilled into peritoneal cavity and have descended producing lower abdominal pain. A lot of gynecological conditions could give similar complaints but because of patient’s PMH, perforated PU should be ruled out first.

Upright abdominal x-ra is positive for air under the diaphragm in the majority of cases of intestinal perforation. If negative, U/S, CT and DPL may be indicated.

10. E.The clinical scenario described is suggestive of acute adrenal insufficiency. Acute onset of nausea, vomiting, abdominal pain, hypoglycemia, and hypotension after a stressful event (e.g., surgical procedure) in a patient who is steroid-dependent is typical. A very important clue to the correct diagnosis in this patient is the past medical history (lupus) indicative of preoperative steroid use. Exogenous steroids depress pituitary-adrenal axis and a stressful situation can precipitate an acute adrenal insufficiency.(Choice B) DKA is also manifested by nausea, vomiting, and abdominal pain; however, you will see hyperglycemia, and you usually do not see hypotension.(Choice D) Intestinal obstruction is not accompanied by hypoglycemia, even though you can see all the rest.(Choice G) Insulin-induced hypoglycemia is manifested by autonomic activation, but nausea, vomiting, and abdominal pain is not the common presentation. Also, hypotension is not typically seen.Severe allergic reaction (Choice F) usually immediately follows the injection of a drug and is frequently accompanied by bronchospasm and urticaria/edema.Atelectasis (Choice H) is an early postoperative complication characterized by fever and is much less dramatic in presentation.An abscess (Choice C) is a late postoperative complication.

11. C.Apart from the acute pancreatitis, this patient’s clinical picture is highly suspicious of two things: hypergastrinemia (recurrent peptic ulcers) and hyperparathyroidism (hypercalcemia). So, serum parathyroid levels and gastrin levels should be performed first (Option C).She may have multiple endocrine neoplasia (MEN I) that is characterized by tumors of anterior pituitary, parathyroid and pancreatic islet cells. MEN II is less likely, but can’t be excluded at this moment as well. MEN II is characterized by pheochromocytoma, medullary carcinoma of thyroid and parathyroid tumors. Serum calcitonin (for medullar carcinoma of thyroid) and VMA will be ordered if there is suspicion of MEN II (Option E). Acid output studies are not reliable for resected stomach (Option A).Educational Objective:Recurrent peptic ulcers with hypercalcemia are best explained by MEN type 1.

12. D.Twenty to thirty percent of duodenal injuries follow blunt trauma, when the duodenum is compressed between the spine and an external solid structure

like a steering wheel, lap belt (as in this case), etc. The second portion of the duodenum, being retroperitoneal and the least mobile, is most commonly injured.Isolated duodenal injuries can be easily missed. Patient may complain of epigastric or right upper quadrant pain, with or without peritoneal signs; however, presentation may be very subtle and requires a high degree of suspicion for diagnosis. Retroperitoneal air or obliteration of right psoas margin on abdominal x-ray is very suggestive. CT scan of the abdomen, with administration of oral contrast material, confirms the diagnosis of duodenal injury. If CT scan is not available, upper GI study with gastrograffin, and if negative, with barium can be used.(Choice A, E) Plain CT scan of the abdomen and USG are not sensitive for duodenal injuries, though they would diagnose the associated injuries.(Choice B) DPL is not sensitive for duodenal injuries, as the second part of the duodenum is the most commonly injured portion and is retroperitoneal.(Choice C) The patient is hemodynamically stable with no signs of penetrative abdominal injury; so, exploratory laparotomy is not warranted.Educational Objective:Duodenal injuries are best diagnosed with CT scan of the abdomen with oral contrast or an upper GI study with gastrograffin, followed by barium, if necessary.

13. C.Early detection of gastric cancer has crucial importance in successful management of gastric cancer because surgical removal of the affected tissues remains the mainstay of the therapy. Unfortunately, almost 90% of patients with gastric cancer are diagnosed at stages III-IV; radical resection is very complicated or impossible in these patients. Evaluation of the extent of the disease after the diagnosis has been made is important in choosing an appropriate management strategy. A CT scan is commonly employed for staging the disease and revealing metastases, especially liver metastases.Laparoscopy (Choice B) can be used to evaluate the patients further and can detect up to 20% of peritoneal metastases missed by a CT scan.Laparotomy (Choice E) is required eventually in most of the patients for radical or palliative surgery with the exception of the patients with unresectable disease.Hypoalbuminemia (Choice A) is sometimes detected in patients with gastric cancer, but it has little diagnostic significance. Serologic markers (Choice B) are of negligible use in these patients.Educational Objective:A CT scan is a standard diagnostic tool employed in patients with newly diagnosed gastric cancer to evaluate the extent of the disease. In most of the patients, surgery is the treatment of choice.

14. B.

Mediastinitis, hemorrhage and large pericardial effusion may account for the widening of the mediastinum. This patient, most likely, has mediastinitis. Antibiotic therapy alone (Choice E) is not sufficient for this very serious disease. Mediastinitis needs thoracotomy for debridement, drainage, and antibiotic therapy (Choice B).Fever, leucocytosis, tachycardia and pain might be the signs of postpericardiotomy syndrome (Choice A), however a “small amount of pericardial fluid” can’t cause widening of mediastinum seen on chest x-ray. For the same reason pericardial puncture (Choice D) is not needed. Postoperative mediastinal hemorrhage (Choice C) is less likely on the 10th day; moreover it can’t explain the fever and leucocytosis.Educational Objective:Recognize the mediastinitis, a post CABG complication by systemic signs of inflammation, chest pain, breathlessness and mediastinal widening on chest x-ray; it is a serious condition and it requires thoracotomy for debridement and drainage.