Módulo 2 Cirugía Flashcards

Question

A 69-year-old man, who smokes and drinks heavily, complains of an earache on his left side. The earache has been present for 6 weeks and is not getting any better despite systemic antibiotics and ear drops. On physical examination, he is found to have very poor oral hygiene, only a few remaining stumps of rotten teeth, and big tonsils that are hard to see because he gags easily. Otoscopic examination shows a perfectly normal right tympanic membrane, although the left is distorted by what appears to be a serous otitis media. Tuning fork testing shows conductive hearing loss on the left but equal bone conduction on both sides. He is afebrile. Which of the following will most likely confirm the diagnosis? (A) Audiometry (B) MRI studies of the eighth nerve (C) Culture of fluid aspirated from the left ear (D) Biopsies of the tympanic membrane and ear canal (E) Panendoscopy and biopsies

Answer 1

Respuesta: E The correct **answer is E**. An old man who smokes, drinks, and has rotten teeth is the perfect candidate to develop squamous cell carcinoma of the mucosa of the head and neck. An unhealing ulcer in the floor of the mouth, a big lymph node on the side of the neck, hoarseness that does not go away, and unilateral earache are the classic presentations. In this case, the tumor is probably occluding the Eustachian tube and leading to the accumulation of fluid in the middle ear. Systematic examination of the entire mucosa, with biopsies, will demonstrate the primary tumor. Audiometry (**choice A**) would document the conductive hearing loss but will do nothing to find the tumor. A tumor of the acoustic nerve (**choice B**) would lead to gradual unilateral hearing loss, but it would be sensory, not conductive. Culture (**choice C**) mistakenly assumes the problem to be infectious in origin. Biopsies of the ear itself (**choice D**) are misplaced. The tumor is not there; it is inside the mouth.

Answer 2

Respuesta: E The correct **answer is E**. Indications for exploratory laparotomy in trauma patients include those with intraabdominal bleeding that has been demonstrated by appropriate tests, but also those with an acute abdomen (severe pain, tenderness, guarding, and rebound tenderness) following abdominal trauma. This woman is probably bleeding into her abdomen (she has no other obvious source). Even if that were not the case, however, she needs an exploratory laparotomy to deal with the source of the acute abdomen, which is bound to be injuries of hollow viscera. Sonogram (**choice A**) is used extensively to diagnose intraabdominal bleeding, but it does not tell us what to do, or not to do, for the acute abdomen. X-ray films (**choice B**) would add little to our decision. Free air under the diaphragm would prove visceral disruption, but the absence of such a finding would not exclude it. CT scan (**choice C**) is excellent in the hemodynamically stable patient in whom the only question is intra-abdominal bleeding. In this case, we are also contending with the acute abdomen. Furthermore, with a systolic blood pressure of 75 mm Hg, this woman cannot afford a trip to the CT scanner. Diagnostic peritoneal lavage (**choice D**) is excellent to prove intraabdominal injury, and is also extensively used to diagnose peritoneal contamination from ruptured hollow viscera. However, the latter is required only when the abdomen cannot be examined reliably (e.g., the drunk or the unconscious patient). This woman is telling us that her belly hurts, and our physical exam is diagnostic.

Answer 3

Respuesta: B The correct **answer is B**. All the findings indicate obstructive jaundice (high alkaline phosphatase, dilated ducts), with gallstones as the source. The fact that no stone can be seen impacted within the common duct is meaningless, since only about 50% of those can be seen by sonogram (the air in the duodenal loop interferes with the study). Endoscopic retrograde cholangiopancreatography (ERCP) can outline the stone and even allow extraction, limiting subsequent surgery to cholecystectomy. Serology (**choice A**) would have been a splendid idea if she had very high transaminases and minimal elevation of the alkaline phosphatase, and if the sonogram had shown normal size ducts. Ampullary cancer (**choice C**) should be suspected in the patient with obstructive jaundice, along with anemia and occult blood in the stool; this is not the case here. Liver biopsy (**choice D**) assumes that we expect intrinsic liver disease, which is not the case here. Neither should we suspect cancer of the pancreatic head (**choice E**) when the gallbladder is contracted rather than dilated and all the signs point to stones as the problem. ERCP will also give us the diagnosis in the case of the rare patient with two diseases (stones plus an unrelated cancer).

Answer 4

Respuesta: C The correct **answer is C**. This is the classic description of Paget disease, an infiltrating cancer of the breast directly underneath the areola that is permeating the skin lymphatics and the skin itself. Although it is true that the areola is not immune to other benign skin conditions, missing the cancer would be lethal. Thus, any other answer that does not seek to rule out cancer first is wrong. Treatment with estrogens (**choice A**) assumes a benign, age-related atrophy, which is common in the vagina but not in the areola. A mammogram and galactogram (**choice B**) are indicated to find intraductal papilloma, the presentation of which is bloody nipple discharge in a younger woman. Looking for a glucagonoma (**choice D**) is a distracter that might appeal to those who are convinced that the USMLE emphasizes bizarre, rare diseases. Indeed glucagonoma shows up as an intractable skin condition, but it is migratory, necrolytic, and exfoliative. It occurs in anemic diabetic patients with glossitis, and shows no preference for the areola. Culture and topical antibiotics (**choice E**) is the intuitive answer if you assume that this is a nasty skin infection, but never make that your first diagnosis in this setting!

Answer 5

Respuesta: C The correct **answer is C**. The clinical picture is that of mitral stenosis, with the apical diastolic murmur plus all the typical symptoms for that condition. As a rule, cardiovascular surgeons prefer to repair the patient’s own mitral valve, rather than replacing it. Stenosis is due to fusion at the commissures, which commissurotomy can correct. A ventricular septal defect (**choice A**) would produce a systolic murmur and, if uncorrected by age 35, would have produced pulmonary vascular damage, with a potential reversal of the shunt and even cyanosis. Although mitral annuloplasty (**choice B**) targets the correct valve, it assumes that the problem is insufficiency rather than stenosis. Had that been the case, the apical murmur would have been systolic, rather than diastolic. Replacement of the aortic valve (**choice D**) would be correct if the patient had a deformed aortic valve, as these cannot be easily repaired. In this case, however, the sick valve is the mitral (with an apical murmur) rather than the aortic, which would have produced a murmur best heard at the base. Replacement of the mitral valve (**choice E**) can be done, and is indeed done, but not as the first choice if repair is possible.

Answer 6

Respuesta: A The correct **answer is A**. Pneumonectomy is the preferred treatment for centrally located non-small cell cancers of the lung. The patient’s pulmonary function studies (prompted by the suggestion of COPD) show that he can tolerate the removal of one third of his current lung capacity, as it would leave him with more than 800 mL forced expiratory volume at 1 second (FEV1 ). However, there is no point in undertaking surgical therapy unless cure is possible, which would not be the case if he has liver metastasis, metastasis on the other lung, or involved mediastinal nodes at or above the carina. CT scan is the first step to answer those questions, before the pneumonectomy is considered. Radiation and chemotherapy (**choice B**) would have been the chosen palliative therapy if metastatic spread had contraindicated surgery. It would also have been the correct answer if the tumor had been small cell, rather than squamous cell, carcinoma. The supraclavicular nodes (**choice C**) can be involved in lung cancer, but they are not the first level. Thus, a negative biopsy would not have given the green light for surgery. If a CT scan does not give a satisfactory answer as to the status of mediastinal nodes, a cervical mediastinal exploration would be the procedure of choice to sample carinal nodes. Lobectomy (**choice D**) is not suitable for central lesions, but it might have been the operation of choice for a peripheral tumor. Pneumonectomy (**choice E**) is indeed our goal, but one would not do it without first making sure that extensive metastases are not present.

Answer 7

Respuesta: C The correct **answer is C**. The clinical picture is classic for a dissecting aneurysm of the thoracic aorta. The presentation resembles that of a myocardial infarction, but it happens in hypertensive patients who develop a wide mediastinum. At one time, only an arteriogram could establish the diagnosis (at considerable risk), but noninvasive imaging is currently preferred. ECG and cardiac enzymes (**choice A**) are usually done on anyone with chest pain, but the results would have been negative here. They would have ruled out infarction but would not establish the alternate diagnosis. Studying the esophagus with Gastrografin swallow, followed by barium if negative (**choice B**), would have been a good idea if the patient had vomited repeatedly before developing the chest pain and if the x-ray film had shown mediastinal air rather than a wide mediastinum. Ventilation-perfusion scan (**choice D**) would actually have been the best choice if a pulmonary embolus had been suspected. Pulmonary angiogram (**choice E**) might have come to mind if he had been immobilized by recent surgery and had then developed signs suggestive of pulmonary embolus: pleuritic pain, shortness of breath, hemoptysis, and distended head and neck veins. Actually, although the angiogram is supposed to be the gold standard in such cases, it is seldom done. Less invasive diagnostic means, as suggested in **choice C**, are preferred.

Answer 8

Respuesta: B The correct **answer is B**. The clinical picture is that of acute epididymitis, which is treated with antibiotics. The differential diagnosis is with testicular torsion. Although all the details in this case point to epididymitis, the consequences of missing a diagnosis of testicular torsion are so dire that sonogram is always done to rule it out with certainty. Orchitis secondary to mumps could produce a painful testicle, and you might think of treating it with antivirals (**choice A**). In this patient, however, neither the history nor physical examination indicates that the parotids are swollen. Cystoscopy (**choice C**) is included as a distracter to emphasize the point that instrumentation of the urinary tract should never be done when there are signs of current urinary tract infection. Testicular tumors (hinted at in **choice D**) are typically painless. If one were thought to be present, however, the correct way to biopsy it would be by inguinal orchiectomy, never by the trans-scrotal route. Surgery and orchiopexy (**choice E**) would be the correct answer for testicular torsion, in which case the testicle would have been high and in a horizontal position, the cord would have been nontender, and neither fever nor pyuria would have been present.

Answer 9

Respuesta: D The correct **answer is D**. The correlation between ureteropelvic junction obstruction and profuse diuresis is classic. A congenital narrowing at the ureteropelvic junction allows normal passage of urine at a normal flow rate, but the lumen cannot accommodate a suddenly increased flow rate. Beer is a wonderful diuretic; if he had never been exposed to it, his congenital anomaly could have remained hidden. Bladder calculi (**choice A**) would give suprapubic pain and symptoms of an irritative bladder. Low implanted ureter (**choice B**) is typically asymptomatic in the male but could lead to incontinence in the female. Ureteral stone (**choice C**) is a good second choice, and it could cause flank pain radiating to the inner thigh and scrotum. However, the youngster who develops colicky flank pain when first exposed to beer is so classic for ureteropelvic junction obstruction that urologists can make the correct diagnosis over the telephone. Vesicoureteral reflux (**choice E**) gives a febrile picture along with flank pain. It is typically seen in younger children, who eventually outgrow their problem.

Answer 10

Respuesta: E The correct **answer is E**. His age and status as a nonsmoker make a primary testicular cancer with lung metastasis far more likely than the opposite combination, or the existence of two unrelated lesions. The fact that the tumor has spread should not preclude attempts at diagnosis and treatment, since most testicular cancers are exquisitely radio- and chemosensitive and may be cured even when they have metastasized. The correct way to diagnose a testicular cancer is by radical orchiectomy via the inguinal route. Palliative care only (**choice A**) is often the best thing to do for far advanced, very aggressive tumors, for which there is no effective treatment anyway. This is not the case for testicular cancer. Do not give up in this case. Cure is still possible. Going after the metastasis first, rather than the assumed primary tumor (**choice B**), makes sense if the metastasis is more accessible, which is not the case here. Furthermore, bronchoscopy is not likely to provide access to a peripheral metastatic lesion. Urologists cringe at the thought of trans-scrotal approaches for testicular cancer, whether for biopsy or excision (**choices C and D**). The tumor is spread to the incision site, complicating further management. The only acceptable biopsy for a testicular mass is a formal orchiectomy by the inguinal route, with high ligation of the cord (“radical orchiectomy”).

Answer 11

Respuesta: D The correct **answer is D**. This is a classic presentation of a ruptured berry aneurysm. There must be a high suspicion for this diagnosis, since failure to make it will likely result in the death of the patient. Although the diagnosis of headache is quite common, the classic pattern is that of a sentinel bleed followed by meningismus and agitation that herald a re-bleed in more than 70% of subarachnoid hemorrhage (SAH) patients within 48 hours. Once the SAH is identified (usually with a CT scan), neurosurgical intervention to stop the bleeding can be begun, and the patient thereafter has a normal life expectancy. The most common nontraumatic cause for SAH is a berry aneurysm in the anterior portion of the circle of Willis. Arteriovenous malformation (**choice A**) is a rare cause of a SAH and intracranial bleeds in general. The cerebellum (**choice B**) is an uncommon site for bleeds. When they do occur, they are generally due to severe hypertension. Such bleeds are urgent because they can cause brain stem compression or obstructive hydrocephalus if not promptly evacuated. The putamen (**choice C**) and thalamus (**choice E**) are the most common sites for hypertensive bleeds. Such bleeds do not produce meningismus, only mental status changes and focal neurologic deficits.

Answer 12

Respuesta: C The correct **answer is C**. Anatomic proximity to major vessels is the main criterion to suspect vascular injury in gunshot wounds of the extremities. Although absent pulses and an expanding hematoma make such an injury virtually certain (and dictate the need for surgical exploration), the presence of normal pulses and the absence of a hematoma do not rule out vascular injury. Noninvasive Doppler studies or, if necessary, an arteriogram can provide the necessary reassurance. Massive external bleeding might be currently prevented by clots. Disturbing them in the emergency department (**choice A**) could lead to a lot of unnecessary excitement in a place ill-equipped to deal with the problem. When vascular injuries are explored in the operating room, proximal and distal control are obtained first, before the wound itself is probed. If his vessels are indeed injured, sending him home (**choice B**) would risk the development of complications, such as late bleeding, vascular occlusion from intimal flaps, or development of an AV fistula. Formal surgical exploration (**choice D**) would be mandatory if he were exsanguinating, had no distal pulses, or had an expanding hematoma. When the only reason to suspect vascular injury is anatomic proximity, a less aggressive approach is indicated. Waiting for complications to develop (**choice E**) would be expensive and lead to higher morbidity.

Answer 13

Respuesta: D The correct **answer is D**. Cirrhotic patients with ascites may develop spontaneous primary bacterial peritonitis, which gives a “mild picture of acute abdomen,” and is identified by growing a single organism out of the ascitic fluid. CT scan (**choice A**) is an excellent way to rule out common intraabdominal conditions that may be suggested by equivocal clinical presentations (e.g., appendicitis, pancreatitis, and diverticulitis). In this case, it would simply show the ascites and nothing else. Thus, it would rule out other things but would not establish the diagnosis. Serum amylase (**choice B**) ought to be the first thought in an alcoholic who develops an acute abdomen, but not if he has not drunk anything for 7 years. This is not the clinical picture of pancreatitis, either. The biliary tract, which a sonogram (**choice C**) would check, can be the source of abdominal pain in a cirrhotic, but it would have the typical clinical presentation of right upper quadrant pain. Laparoscopy (**choice E**) is being used in lieu of exploratory laparotomy when “taking a peek in the abdomen” would establish a diagnosis. It would be a rather invasive way to show that this man has nothing other than ascitic fluid in his abdomen. Furthermore, there would be a risk of prolonged postoperative leak of ascitic fluid through the incision sites.

Answer 14

Respuesta: A The correct **answer is A**. The clinical diagnosis is obstructive jaundice (high alkaline phosphatase, dilated biliary ducts), which is malignant in nature (thin walled, distended, palpable gallbladder) and probably due to cancer of the head of the pancreas (bulky tumor producing weight loss and back pain). The tumor can probably be seen in the CT scan, which is the least invasive of the proposed imaging studies. Serologies (**choice B**) would be in order if we suspected hepatitis, which would be the case if the transaminases were very high, the alkaline phosphatase only modestly altered, and the ducts not dilated in the sonogram. Duodenal endoscopy and biopsies (**choice C**) would be the first choice if we suspected cancer of the ampulla of Vater, in which case there would be no pain and probably no weight loss, but there would be anemia and occult blood in the stools. ERCP (**choice D**) is the first choice if stones are suspected. In that case, however, there would be a nondistended gallbladder with stones in it. When pancreatic cancer is suspected, ERCP is the next test to do if the CT scan is negative and we therefore assume either that the pancreatic cancer is very small or that there is common duct cancer. Percutaneous transhepatic cholangiogram (PTC) (**choice E**) does the same as ERCP (put dye directly into the ducts) and is also invasive. If we elected to do PTC instead of ERCP, it would still be preceded in this case by the CT scan, which might render either test unnecessary.

Answer 15

Respuesta: B The correct **answer is B**. Progressive headache that is worse in the mornings and present for several months indicates a brain tumor. Furthermore, the papilledema and projectile vomiting leave no doubt about the presence of increased intracranial pressure, something that a brain tumor eventually will produce. Do not be fooled by the absence of other neurologic symptoms; that can happen when tumors press on a “silent area” of the brain. Brain abscess (**choice A**) is also an intracranial mass that can do the same things described here, but the timetable would be shorter (days or weeks) and the source of infection would be described in the vignette (mastoiditis or frontal sinusitis, for instance). Chronic subdural hematoma (**choice C**) affects very old or alcoholic patients, who gradually lose their mental capacity after trivial trauma to the head. Degenerative diseases, like multiple sclerosis (**choice D**), typically have on and off neurologic deficits for years before they are diagnosed. Subarachnoid bleeding from an intracranial aneurysm (**choice E**) can indeed strike a young person, but the presentation is an extremely intense headache of sudden onset, “like a thunderclap.”

Answer 16

Respuesta: D The correct **answer is D**. The clinical picture and the radiographic description are those of a sigmoid volvulus, a common condition in elderly patients. The endoscopic instrument can untwist the bowel from the inside, relieve the obstruction, and allow placement of a long rectal tube. Repeated episodes may require corrective surgery. The combination of nasogastric suction, IV fluids, and observation (**choice A**) is a conservative approach that is appropriate when adhesions are the suspected reason for obstruction affecting only the small bowel. This will occur in patients with a previous laparotomy. Enemas and laxatives (**choice B**) are often needed in elderly patients who develop fecal impaction. However, an empty rectal vault in the physical exam excludes that diagnosis. Arteriogram (**choice C**) comes to mind for the other common abdominal catastrophe in the elderly: mesenteric embolus. In that setting, however, one expects atrial fibrillation or a very recent myocardial infarction as the source of the clot. In addition, the patient is typically sicker and has a silent abdomen and blood in the stool. The x-ray film would show small bowel distention and distention of the colon up to the middle of the transverse, but no huge loop or parrot’s beak. Exploratory laparotomy (**choice E**) would be needed if the loop could not be straightened out and emptied endoscopically, or if the patient had signs of strangulation (e.g., fever, an acute abdomen).

Answer 17

Respuesta: E The correct **answer is E.** At one time, all full thickness burns were allowed to heal by granulation over a period of 2 or 3 weeks, before skin grafting was done. The area was kept free of bacteria by the use of topical agents, such as the ones listed in the alternate answers. The process was expensive, painful, time-consuming, and prone to complications. The current preference is to do immediate excision and grafting of burned areas that appear to be full thickness, if they are not very extensive. This one is a perfect example. If the extent of the burn precludes early excision and grafting, mafenide acetate (**choice A**) is used in areas where deep penetration is needed. Otherwise it is not a first choice because it hurts and can produce acidosis. Silver sulfadiazine (**choice B**) is the “workhorse” of burn wound antibacterial therapy, but as pointed out, it would be a perfect choice only if we had to go the slow route of preparing the area for delayed skin grafts. Triple antibiotic ointment (**choice C**) is preferred for burns around the eyes, as the other two topical agents are very irritating. Debridement is often indicated in the long-term preparation of an area to be grafted, but wet-to-dry dressings (**choice D**) would be less effective than antibacterial agents. In any event, we want immediate excision and grafting for this patient.

Answer 18

Respuesta: A The correct **answer is A**. The mechanism of injury suggests anterior cord syndrome, because the burst vertebral bodies are more likely to damage the anterior part of the cord that lies right behind them. The final neurologic deficits confirm it, since the only preserved functions are those that travel in the posterior part of the cord. Central cord syndrome (**choice B**) is seen with hyperextension injuries of the neck, resulting in severe deficits in the upper extremities but better preservation of function in the lower extremities. Complete cord transection (**choice C**) would have no function at all below the level of the lesion. Hemisection (**choice D**) would have the classic “split deficits,” i.e., below the lesion some functions are affected on one side and a different set of functions are affected on the other. Spinal shock (**choice E**) was present in this patient right after the injury (nothing worked), but it is not the final lesion.

Answer 19

Respuesta: A The correct **answer is A**. Hip pathology often presents with knee pain, and in this case the problem is clearly in the hip. Age is the next clue. Avascular necrosis (also known as idiopathic aseptic necrosis, or Legg-Calve-Perthes disease) occurs typically in this age group, with preference for boys rather than girls. Developmental dysplasia (**choice B**) is present at birth (it used to be called congenital dislocation of the hip, a name that was changed for medicolegal reasons) and, if untreated, would have caused problems earlier. Osteomyelitis (**choice C**) is usually seen in peripheral bones, following a febrile illness in toddlers. Fever is also usually seen at the time that the osteomyelitis has developed. The same is true of a septic hip (**choice D**), which should be suspected when a toddler with a recent febrile illness suddenly refuses to move a hip and has so much pain that he does not allow anyone to examine it. Slipped capital femoral epiphysis (**choice E**) should be suspected when a chubby, 12- to 14-year-old boy shows up with hip pain and inability to internally rotate the hip. Age, again, is the first clue.

Answer 20

Respuesta: D The correct **answer is D**. The patient has already sustained the neurologic damage due to the initial blow and is not threatened by a single large hematoma displacing the midline structures. However, she is still vulnerable to further neurologic impairment resulting from the development of increased intracranial pressure. If the intracranial pressure is medically prevented or minimized (with fluid restriction, diuretics, and hyperventilation), her chances of recovery are somewhat better. The patient has normal vital signs; therefore, infusing IV fluids (**choice A**) would not help. If she had been in shock, the brain would have suffered from inadequate perfusion, and restoring intravascular volume would have been a good idea. In this case, the additional fluid would simply compound the problem of increased intra-cranial pressure. Systemic vasodilators (**choice B**) would decrease intravascular pressure and work against the local vasoconstriction that hyperventilation would have offered. The end result would be less cerebral perfusion. Hyperbaric oxygen (**choice C**) has no role in the prevention or treatment of increased intracranial pressure. Surgical evacuation (**choice E**) is indicated for hematomas that are displacing the midline structures.

Answer 21

Respuesta: E The correct **answer is E**. The differential diagnosis of severe postoperative chest pain with tachycardia and shortness of breath is between myocardial infarction and pulmonary embolus. Timing offers the first clue: Myocardial infarction typically occurs within the first 2 to 3 days, whereas pulmonary embolus is more commonly seen after 5 to 7 days. Although postoperative myocardial infarction often does not have the typical chestpain pattern, this case presents with pain of a fairly typical nature and radiations. Both ECG and enzymes are used to confirm myocardial infarction, with enzymes being more reliable. Blood gases (**choice A**) would be the first step to build a case for pulmonary embolus, in which case they would show hypoxia and hypocapnia. However, the timing does not suggest pulmonary embolus, and the absence of distended veins almost completely excludes that diagnosis. A chest x-ray film (**choice B**) is nonspecific for either of the two diagnoses under consideration. Other problems that could be diagnosed with a chest x-ray film in this setting, such as atelectasis, pneumonia, or pneumothorax, could account for shortness of breath but not for chest pain. Pulmonary angiogram (**choice C**) is the ultimate, “gold-standard” test for pulmonary embolus. It is seldom done clinically (ventilation-perfusion scan is more commonly used), and, as noted above, it addresses a problem that clinically has already been excluded or made much less likely. Transaminases (**choice D**) would be very helpful in the differential diagnosis of jaundice, but they have no role in identifying the source of chest pain.

Answer 22

Respuesta: D The correct **answer is D**. Rubbery, movable breast masses in young women are fibroadenomas, and a rapidly growing variant is known to affect adolescents. Cancer (**choice A**) is virtually unknown in this age group. Cystosarcoma phyllodes (**choice B**) grows to very large size, but it does so over a period of several years. It starts in women in their early or mid twenties, and reaches large size by the time they are in their late twenties or early thirties. Mammary dysplasia (**choice C**) is typically seen in women aged 20- 40. It is characterized by painful breasts and recurrent formation of cysts. Intraductal papilloma (**choice E**) is the least likely answer. Those tumors produce bloody nipple discharge, and their size is measured in millimeters.

Answer 23

Respuesta: C The correct **answer is C**. The double bubble sign with a little gas beyond is highly suggestive. The diagnosis must be promptly confirmed (by barium enema or contrast study from above) so that emergency surgery can be performed before the bowel dies twisted on its vascular pedicle. This condition can be present at birth or it can also show up later, as in this example. Hypertrophic pyloric stenosis (**choice A**) is suggested by the age (it presents at 3 weeks). However, the vomiting would have been projectile and free of bile, and x-ray films would have shown only gastric distention. Intestinal atresia (**choice B**) shows up at birth, and the x-ray films show multiple air fluid levels. Meconium ileus (**choice D**) is also obvious earlier in life, but the infant would have cystic fibrosis, an unused microcolon, and inspissated meconium in the ileum giving a ground glass appearance in the x-ray films. Necrotizing enterocolitis (**choice E**) occurs in the premature infant when first fed.

Answer 24

Respuesta: D The correct **answer is D**. The mechanism of injury and symptomatology are consistent with fracture of the scaphoid bone. The most important clue to diagnosis is the presence of pain on pressure in the “anatomic snuffbox.” Plain x-ray films in the first 24-48 hours usually fail to reveal evidence of fractures, and the patient may be mistakenly diagnosed as having a sprain. In the presence of the characteristic history and findings on physical examination, appropriate treatment for presumptive scaphoid fracture should be instituted, until proven otherwise. Bone scanning (**choice A**) may be performed to confirm the presence of scaphoid fracture. It is more sensitive than plain x-rays, but it frequently gives false negative results in the first 48 hours following trauma. MRI examination of the wrist (**choice B**), as well as CT scans, can be performed if there is a need for prompt confirmation of the clinical suspicion of scaphoid fractures. However, these radiologic investigations are not cost-effective. Treatment for wrist sprain (**choice C**) is the most common mistake when dealing with scaphoid fractures, especially because plain x-ray films are often negative in the first day or two after the fracture occurs. Missed scaphoid fracture is among the top 10 reasons for malpractice suits.

Answer 25

Respuesta: D The correct **answer is D**. Despite prophylactic treatment with low-dose heparin, this patient has developed signs and symptoms of pulmonary thromboembolism (PTE). This case highlights the diagnostic problems in the clinical approach to PTE, which is frequently encountered in a hospital setting. Ventilation-perfusion scan cannot be expected to be diagnostic in the presence of areas of atelectasis and pneumonic infiltrates. Therefore, spiral CT scan of the chest is a better diagnostic choice. Bronchoalveolar lavage (**choice A**) has no role in the diagnosis of PTE. It is most useful in obtaining samples of lower respiratory tract secretions to determine the etiologic agent of pneumonia. Contrast venography (**choice B**) is used to investigate the presence of deep venous thrombosis (DVT), but it should not be the first diagnostic method in the diagnostic workup of possible PTE. Pulmonary angiography (**choice C**) is the definitive diagnostic method for PTE, but it should be used only after noninvasive procedures have failed. Ultrasonography of the lower extremities (**choice E**) is a noninvasive method of diagnosing DVT. This procedure (as well as any other test for DVT) should also be carried out only if ventilation-perfusion scanning gives equivocal or inconclusive results. Ventilation-perfusion lung scanning (**choice F**) is frequently performed to diagnose pulmonary emboli. However, as is pointed out above, the test is not reliable if there are areas of atelectasis and pneumonic infiltrates in the chest x-ray.

Answer 26

Respuesta: B The correct **answer is B**. The relationship between smoking and bladder cancer is even more significant than the well-known relationship between smoking and lung cancer. This man is a prime candidate for bladder cancer. His workup has been appropriate until now because the intravenous pyelogram (IVP) is often the first test done in patients with hematuria. This study diagnoses renal cell carcinomas and ureteral tumors, but it is notoriously inaccurate for early bladder cancers. Thus, the patient’s workup has not been completed, and he now needs a cystoscopy. CT scan of the kidneys (**choice A**) is also an excellent study for diagnosing renal cell carcinoma, but this diagnosis has already been excluded with the IVP, and the CT scan is not the best test to find early bladder cancers. We are not ready to prescribe medications (**choice C**). Valuable time will be wasted if we assume that the patient has a urinary tract infection or prostatitis (for which we have no convincing findings) and we go for a trial of therapy. The patient will not respond to it, and, eventually, we will have to look into his bladder. A 65-year-old man with hematuria, a normal IVP, and a very strong history of smoking needs an immediate cystoscopy. Hematuria is not the typical presentation for prostatic cancer. Prostatic cancer is found by discovering a hard nodule on rectal exam, or by being alerted by a high PSA, neither of which is present here. Thus, there is nothing to biopsy in that organ (**choice D**). Retrograde cystogram (**choice E**) is used to rule out bladder injuries in trauma patients. It is not the best test for early bladder cancer. In fact, we have already injected radioopaque dye in this patient’s bladder (as part of the IVP), and it failed to outline the tumor.