Módulo 1 Cirugía Flashcards

Question

A 55-year-old-woman of Asian descent goes to the emergency department because of vomiting and severe abdominal cramping of 3 days’ duration. Her pain is centered on the umbilicus. She denies being exposed to a viral or bacterial illness. Her medical history includes a previous cholecystectomy and an appendectomy after which she developed an infection. Her abdomen is not tender, but hyperactive, high-pitched peristalsis with rushes coincides with palpable bowel cramping. Abdominal x-ray films taken in the supine and upright positions demonstrate a ladder-like series of distended small bowel loops. Which of the following is the most likely explanation for these findings? (A) Adhesions (B) Ascaris infection (C) Cancer (D) Intussusception (E) Volvulus

Answer 1

Respuesta: A The **correct answer is A**. The clinical and radiologic findings are typical of small bowel (jejunoileal) obstruction. If the pain becomes continuous and bowel sounds vanish, suspect that strangulation has occurred. The most frequent causes of small bowel obstruction are adhesions and incarceration in hernias. To investigate adhesions, look for a history of peritonitis, Crohn disease, pelvic inflammations, or abdominal or pelvic surgery. Overwhelming Ascaris infection **(choice B)** can cause small bowel obstruction, most frequently in poorly developed, third-world tropical countries. Cancer **(choice C)** of the duodenum or pancreas is the most common cause of obstruction of the duodenum, but the ladder-like series of dilated bowel loops would not be seen because the obstruction would be proximal to the ileum. Intussusception **(choice D)** is relatively common in infants but is much rarer (and usually related to tumor) in adults. Volvulus **(choice E)** is rare in the midgut.

Answer 2

Respuesta: C The **correct answer is C**. In gunshot wounds of the upper zone of the neck, the main concern is the possibility of significant vascular injuries. The area is too high to involve the aerodigestive tract, and it is also rather difficult to explore surgically. Arteriogram offers the best way to assess the extent of the injuries, and also provides a way for embolization of major arteries that might be bleeding significantly. Clinical observation **(choice A)** is the second best answer, but it would delay recognition of significant vascular injuries that the arteriogram might demonstrate. Clinical observation is often all we do in asymptomatic stab wounds, where serious damage is less likely to occur. Barium studies **(choice B)** are essential when one suspects esophageal injury that is not demonstrated by gastrografin swallow. As pointed out above, however, the area of injury here is well above where the esophagus begins. Endoscopy **(choice D)** is incorrect for the same reasons that barium studies have no role in this case: the trajectory of the bullet is too high to involve the aerodigestive tract. Surgical exploration **(choice E)** might be unavoidable in hemodynamically unstable patients whose vascular injuries cannot be controlled by arteriographic embolization. Surgery can be performed in this area if needed, but for technical reasons it is not our first choice of management.

Answer 3

Respuesta: A The **correct answer is A**. There are two favorable findings in this patient: Her axillary lymph nodes do not have metastasis, and her tumor is strongly positive for hormonal receptors. However, everything else is unfavorable: The tumor is quite large, and the prognostic factors are all unfavorable. Clearly, the patient would benefit from chemotherapy, and she should be placed on hormonal therapy after chemotherapy and radiation therapy to take advantage of the positive hormonal receptors. The objective of the hormonal manipulations is to either block her receptors (with tamoxifen) or suppress the production of estrogens (with anastrozole). Randomized studies have shown that anastrozole is considerably more effective than tamoxifen in postmenopausal patients. Thus, it has become the drug of choice for that group. Chemotherapy and tamoxifen **(choice B)** would be the best course of action for premenopausal patients, for whom anastrozole is not yet approved as the best drug. Chemotherapy and tamoxifen would have been the regimen for this patient before the advent of anastrozole. Adding estrogens and progesterone to the chemotherapy **(choice C)** would be contraindicated. We want to deprive the tumor of the stimulation provided by those hormones. Completion of the operation to a more radical form of resection **(choice D)** has no benefits. The patient has a very large margin of normal tissue around the tumor, all the margins are negative, and the patient has agreed to postoperative radiation. We do not cure breast cancer by cutting out more normal tissue. We do it by treating the systemic spread of the disease. Radiation therapy **(choice E)** is focal in nature. It does not treat distant metastatic spread. The patient needs radiation to the breast that had the tumor to minimize the rate of local recurrence. Radiating the other breast and the axilla would not be helpful.

Answer 4

Respuesta: E The **correct answer is E**. A woman of this age who is found to be anemic and have occult blood in the stool should be suspected of having a cancer on the right side of the colon. Thus, the colonoscopy that was initially planned was the appropriate study. However, the patient also has obstructive jaundice, which is most likely of malignant origin (she has the sonographic equivalent of a positive Courvoisier-Terrier sign). Good clinical thinking involves attempting to find one single disease that explains all of the concurrent findings. Therefore, assuming that the patient has colon cancer plus a cancer of the head of the pancreas is not a good bet. A single tumor that would bleed into the gastrointestinal lumen and obstruct the common duct is ampullary carcinoma, and upper gastrointestinal endoscopy should identify it. If we insist in ruling out colon cancer, colonoscopy could be done during the session in which upper gastrointestinal endoscopy is performed. Barium enema **(choice A)** would be a less attractive alternative. The problem is not in the liver and, thus, a CT scan **(choice B)** or a biopsy **(choice C)** of the organ is a misguided effort. Dilated intrahepatic ducts and dilated extrahepatic ducts point to a low obstruction of the biliary tree. They are not suggestive of liver metastasis or liver pathology. The laboratory findings are also suggestive of biliary obstruction rather than hepatocellular disease. Further definition of the nature of biliary obstruction can be obtained with an endoscopic retrograde cholangio-pancreatogram (ERCP) or a percutaneous transhepatic cholangiogram **(PTC; choice D)**. However, if we suspect that the obstructing tumor grows out of the duodenal wall, performing the study via a liver puncture (i.e., PTC) will miss the pathology. ERCP would find it, but, in fact, the full study would not have to be completed: As soon as the endoscopist looks at the ampulla, the tumor will be discovered. Cannulation of the ducts and injection of dye would not be needed.

Answer 5

Respuesta: B The **correct answer is B**. This is actually the ideal candidate for breast-sparing surgery: a patient with a small primary tumor in a large breast, located far away from the nipple and areola. Provided radiation is done afterward, the cure rates are identical to those for more mutilating procedures. The cosmetic outcome is excellent, and no reconstruction is needed (the void left by the lumpectomy fills in with body fluids and is eventually replaced by connective tissue). No surgery at all **(choice A)** is not an option. As much as we want to preserve the breast, and as much as we rely on postoperative radiation to lower the local recurrence rates, leaving the primary tumor in place does not lead to cure. Simple mastectomy **(choice C)** entails more surgery than needed for the tumor (for which a lumpectomy followed by radiation is sufficient in this case), but not enough to learn about the status of the axillary nodes. They have to be sampled (either by dissection or sentinel node biopsy). Physical examination is totally unreliable for that purpose. Although modified radical mastectomy **(choice D)** may be unavoidable in patients with larger primary tumors in smaller breasts, or tumors located where the nipple and areola can’t be preserved, this patient does not need that larger operation (no survival advantage) and shouldn’t take the more complicated and less pleasing breast reconstruction. Old-fashioned radical mastectomy **(choice E)** is unnecessarily aggressive and not justified unless the tumor is huge and invading the pectoralis muscle. Unless surgical margins are positive for tumor, postoperative radiation would be equally unnecessary if the whole breast is taken.

Answer 6

Respuesta: C The **correct answer is C**. Fever on the first postoperative day is almost invariably from atelectasis, the treatment of which requires active participation and cooperation from the patient. If atelectasis does not resolve, it leads to the development of pneumonia, which can be identified in chest x-ray films and confirmed with sputum cultures. At that time the process is no longer purely mechanical, but is also infectious, thus requiring antibiotics. Deep venous thrombosis **(choice A)** occurs about 5-7 days after surgery and is a “hidden” source of fever, i.e., nothing else seems to be wrong. This patient is clearly a candidate for thrombosis (he lies in bed doing nothing all day), but right now his problem is probably in the lung. The urine **(choice B)** is a good possibility when the fever starts on day 3, but the persistence of fever since day 1 points to the lung. Three days is too soon for a wound infection **(choice D)** to be the cause of the fever. Five to seven days is a more likely time frame. Looking for an abdominal abscess **(choice E)** is a little premature on the 3rd day after surgery. These typically take a week to 10 days to develop.

Answer 7

Respuesta: C The **correct answer is C**. Sensory fibers of the ninth (glossopharyngeal) nerve are in the vicinity of the digastric muscle, and can be damaged by retraction and dissection in the area. The lack of sensory input at the base of the tongue prevents the normal protective reflex that closes the glottis when swallowing liquids. Unilateral injury to the main trunk of the vagus **(choice A)** in the neck would produce symptoms from the recurrent fibers that innervate the larynx, producing a hoarse voice but no change in swallowing. Injury to the mandibular branch of the facial nerve **(choice B)** would produce drooping of the corner of the mouth and leaking of fluid at that level. Soup running out of the corner of the mouth is annoying, but swallowing is not affected. If the superior laryngeal branch of the vagus is damaged **(choice D)**, the voice tires easily. Swallowing is not affected. The twelfth nerve **(choice E)** is the most commonly damaged nerve during carotid endarterectomy because it crosses the internal and external carotids a short distance cephalad to the bifurcation. However, the outcome is deviation of the tongue to the affected side.

Answer 8

Respuesta: B The **correct answer is B**. A well-known risk of abdominoperineal resection is damage to the erectile nerves, as the rectum is widely dissected away from the pelvic walls. A 50% incidence of postoperative impotence is commonly quoted. “Nerve sparing” surgery can be done if the dissection is closer to the rectal wall, but the extent of the tumor may preclude it. A T3 (which this man had) is a large, bulky, primary tumor. Arterial insufficiency **(choice A)** will lead to impotence either of sudden onset after perineal trauma (motorcycle accident, for instance) or of very gradual development in chronic vascular disease. Psychogenic impotence **(choice C)** has a sudden onset but is partner- or situation-specific. Typically, nocturnal erections are preserved, as is the ability to masturbate. Tumor invasion **(choice D)**, if it is into the pelvic tissues, may indeed require a dissection that damages the nerves, but the problem would not involve the urethra. Venous incompetence **(choice E)** is a common source of organic impotence, which would have gradual onset and no connection with pelvic surgery.

Answer 9

Respusta: D The **correct answer is D**. Nowadays, when thousands of patients are awaiting transplants and many die before they get them, every potential donor should be evaluated by the experts. They may indeed reject some, but probably very few. For instance, corneas can be harvested even from people with cancer, and donors with chronic viral infections can be used for patients who have the same viral disease. All the other options were at one time or another used to exclude donors. These situations still make solid organs less attractive, but not to the extent that evaluation should be precluded.

Answer 10

Respuesta: The **correct answer is D**. This is a typical history for fracture of the posterior lateral talar tubercle; this fracture also occurs in basketball and tennis players who come down hard after a jump. This type of fracture is a fairly common foot injury that you should be able to clinically recognize. The diagnosis can be confirmed with lateral x-ray films of the ankle. Treatment is with immobilization in a cast for 4-6 weeks. Anterior Achilles tendon bursitis **(choice A)** would also cause pain behind the foot/ankle, but would develop more slowly. Calcaneal spur syndrome **(choice B)** causes heel pain and usually develops slowly. Epiphysitis of the calcaneus **(choice C)** is a painful cartilage break in the heel of young children in whom the two centers of ossification of the calcaneus have not yet fused. Posterior tibial nerve neuralgia **(choice E)** causes pain (sometimes burning) around the ankle and sometimes extending to the toes; the pain is worse on walking.

Answer 11

Respuesta: C The **correct answer is C**. You probably had no trouble discerning that bacterial endocarditis, triggered by the use of nonsterile IV drugs, damaged a heart valve in this man. Although we usually think of the right-sided valves as the ones that are first in line to catch the bugs, any valve can become the seat of infection. The clinical presentation leaves no doubt that the aortic valve is the one that has been destroyed: the murmur is systolic, at the right base, and the very low diastolic pressure reveals the incompetence of the aortic valve. Furthermore, this was not a slow process allowing for compensation: he is in failure and close to death. He needs a new valve, pronto! Closure of the ventricular septal defect with a pericardial patch **(choice A)** would have been more appropriate for a massive myocardial infarction producing a septal defect. The clinical presentation would have been different, with a systolic murmur and normal diastolic pressure. Elective repair **(choice B)** is wrong for at least two reasons: it would not address an acute problem, and the criteria given were those for long-standing aortic stenosis (not insufficiency). The mitral valve **(choice D)** does not produce the symptoms described. The pulmonic valve **(choice E)** is not the culprit either. If it were destroyed, it would give few manifestations (it is almost a “disposable” valve).

Answer 12

Respuesta: D The **correct answer is D**. This patient experienced a severe deceleration injury. He is hypotensive, tachycardic, and minimally responsive. He is in hemorrhagic shock. The chest x-ray reveals a widening mediastinum, suggesting a rupture of the thoracic aorta, which is a common catastrophic injury in deceleration accidents. This patient is in grave danger. After confirmation of the diagnosis by spiral CT scan, the treatment is immediate surgical repair of the injury with fluid and blood resuscitation. Cardiac contusion **(choice A)** is common in blunt-force injuries in which the steering wheel has crushed the chest. Arrhythmias, bundle branch block, or ECG abnormalities mimicking infection may occur. Pericardial effusion or rupture may develop. Cardiac tamponade **(choice B)** is associated with hypotension and tachycardia. However, pulsus paradoxus (systolic blood pressure drops >10 mm Hg on respiration) and distant heart sounds might be discovered on physical examination, and his central venous pressure would be high. Chest x-ray films would show an enlarged cardiac silhouette. The ECG would exhibit low limb-lead voltage and variable QRS amplitude (electrical alternans). However, pericardiocentesis is both the diagnostic and therapeutic procedure of choice. Flail chest **(choice C)** is diagnosed when a part of the chest wall bound by fractured ribs moves paradoxically during respiration. Ventilation is hampered. Tension pneumothorax **(choice E)** occurs when air can enter but not leave the pleural space. The mediastinum appears to be shifted to the contralateral side on chest x-ray films. A region without peripheral lung markings outlined by a sharp pleural margin is characteristic. Breath sounds are depressed or absent on the affected side.

Answer 13

Respuesta: C The **correct answer is C**. This man is not a surgical candidate, thus ruling out pneumonectomy **(choices D and E)**. With a central lesion, he would require a pneumonectomy rather than a lobectomy. After resectional pulmonary surgery is done, however, a patient must be left with at least 800 mL in the FEV1 to live a semi-decent life. Anything less than that would make him a pulmonary cripple, or outright kill him. Because of his COPD, this patient is already severely limited, with a total FEV1 of 1100 mL. Were the bad lung to be removed, he would be left with only 40% of 1100 mL: 440 mL. The only option left is radiation and chemotherapy. CT scan of the upper abdomen to rule out liver metastasis **(choice A)** and mediastinoscopy to biopsy carinal nodes **(choice B)** are necessary steps to establish curability. There is no point in doing a pneumonectomy if there are liver or carinal node metastases. But if a pneumonectomy cannot be done for reasons of poor function, there is no point in finding out whether the other limiting factors are present.

Answer 14

Respuesta: E The **correct answer is E**. The child has testicular torsion, one of the very few true urologic emergencies. He needs immediate de- torsion if the testis is to be saved. No time should be wasted doing further studies. Symptomatic care **(choice A)** is fine for testicular trauma with scrotal hematomas. In this case, it would amount to malpractice. A sonogram **(choice B)** is always done when the clinical diagnosis is epididymitis, and we want to be sure that torsion is not being overlooked. But when the clinical diagnosis screams “torsion,” as in this vignette, time wasted confirming the diagnosis with the sonogram could lead to loss of the testicle. Antibiotics **(choice C)** are effective therapy for acute epididymitis, the condition with which testicular torsion may be confused. But the patient with epididymitis is usually somewhat older (sexually active) and has fever, pyuria, a very tender cord, and a normally positioned testicle. Testicular biopsy **(choice D)** is done when we think that the diagnosis is cancer, but the scenario would be a painless mass in a young male.

Answer 15

Respuesta: C The **correct answer is C**. Squamous cell carcinoma of the penis is admittedly a rare form of cancer in the U.S. (about 1% of all cancers in males). It is virtually unknown in nations that practice early (i.e., in infancy) circumcision. It presents as a fungating or ulcerated mass on the glans penis or in the sulcus between the prepuce and the glans. Carcinogenic agents forming in the smegma are suspected to play a pathogenic role, which may be enhanced by lack of circumcision. Other risk factors include lesions (condyloma acuminatum) due to human papillomavirus (HPV) types 16 and 18. Genomic material from these HPV types has been demonstrated in numerous cases. No association has been observed between penile cancer or its precursors and other types of HPV, such as type 6 **(choice B)** or 11. Psoriasis is associated with a slightly increased risk. Balanitis xerotica obliterans **(choice A)** results in fibrosis and thickening of the prepuce. This condition does not seem to confer a significantly increased risk of developing penile carcinoma. Peyronie disease **(choice D)**, which is a form of fibromatosis affecting the penis, results in induration, nodularity, and deformities. It causes severe functional deficits but is not associated with increased risk of cancer. This condition is akin to other forms of fibromatosis, such as Dupuytren contracture. The primary stage of syphilis **(choice E)** manifests with a painless, sharply demarcated ulcer (chancre) often located in the glans. There is no association between syphilis and penile cancer.

Answer 16

Respuesta: C The **correct answer is C**. This patient has scapular “winging,” a protrusion of the scapula when the ipsilateral outstretched arm is pressed against a wall. Scapular winging results from paralysis of the serratus anterior muscle, which functions to carry the scapula forward and assist the deltoid in raising the arm. The serratus is innervated by the long thoracic nerve, which is derived from the fifth, sixth, and seventh cervical nerve roots. This woman had an axillary lymph node dissection that may have damaged the inferior part of the brachial plexus, leading to long thoracic nerve damage, paralysis of the serratus, and scapular winging. The intercostal nerves **(choice A)** arise from the thoracic nerve roots and innervate the intercostal muscles of the chest wall. The lateral pectoral **(choice B)** and medial pectoral **(choice D)** nerves innervate the pectoralis major and minor muscles. The thoracodorsal nerve **(choice E)** innervates the latissimus dorsi muscle.

Answer 17

Respuesta: B The **correct answer is B**. In patients sustaining trauma, there is a chance of bony cervical spine injury. Iatrogenic injury is to be avoided by immobilization of the cervical spine until bony injury is ruled out by lateral cervical spine x-ray. An echocardiogram **(choice A)** would not be appropriate with a normal physical examination and no suspicious cardiac findings. CT scan of the abdomen **(choice C)** or peritoneal lavage **(choice E)** are useful for evaluating the degree of abdominal injury when abdominal examination is inadequate, especially in an unconscious trauma patient. CT examination of the head **(choice D)** is required for patients with altered mental status or for those in whom an intracranial bleed is suspected.

Answer 18

Respuesta: A The **correct answer is A**. Pulmonary artery (Swan-Ganz) catheters are ubiquitous in critical care settings; a basic ability to interpret data from them is vital to the practice of inpatient hospital medicine. This patient has a low cardiac output and a high filling pressure (>18 mm Hg) and is hypotensive. Therefore, this patient’s shock syndrome is cardiogenic. Cardiogenic shock is caused by a number of underlying problems, but the end result is left ventricular failure. This also accounts for the secondarily high rightsided pressures and filling pressures (left heart failure causes right heart failure). Acute mitral regurgitation **(MR; choice B)** is a possibility in this case. At first glance, acute MR could account for all of the patient’s findings, both on physical examination and pulmonary artery catheter. However, unless the acute MR occurred in the setting of acute ischemia, there is no way to account for the severely depressed cardiac output (LV function). Therefore, isolated acute MR from a papillary muscle rupture or chordae rupture could not alone account for all of this patient’s findings. Acute right heart failure **(choice C)** is incorrect because it fails to explain the elevated left-sided filling pressures. Hypoxic pulmonary vasoconstriction **(choice D)** would acutely produce elevated pulmonary artery pressures and possibly right heart failure over the long term, but not in an acute manner. Sepsis syndrome **(choice E)** is defined as hyperdynamic cardiac output (supraphysiologic) with systemic hypotension. This patient has a depressed output, not compatible with sepsis.

Answer 19

Respuesta: D The **correct answer is D**. Even if you do not remember all the spinal cord tracts and pathways, you should recognize that deficits in one set of functions below the injury on one side, combined with deficits in a different group of functions on the other side, spells out hemisection. Furthermore, such clean-cut division of one side of the spinal cord can happen only with a knife or a bullet, which is the setting in this vignette. Anterior cord syndrome **(choice A)** is characterized by sparing of the posterior columns, with preservation of vibration and position sense. The etiology is typically vascular. Central cord syndrome **(choice B)** is seen in whiplash injuries, in which it produces severe deficits in the upper extremities, with relative sparing of the lower extremities. Sensory loss consists of loss of pain and temperature sense in a “cape” distribution over the shoulders, lower neck, and upper trunk with posterior column function (light touch, vibration, conscious pro-prioception) relatively preserved. Complete transection **(choice C)** would result in spastic paralysis below the level of the injury with flaccid paralysis at the level of the injury. Ascending sensory fibers would also be interrupted, producing a total sensory deficit below the level of the lesion. Posterior cord syndrome **(choice E)** would result in selective loss of conscious proprioception, vibratory sense, stereognosis, graphesthesia, and two point discrimination. It is fairly rare.

Answer 20

Respuesta: A The **correct answer is A**. Crush injury results in massive tissue damage. There are obvious organ-specific consequences of such injury, but it is the musculoskeletal system that is the focus of this question. Massive necrosis and lysis of muscle releases intracellular myoplasm components that are toxic in high concentrations. Examples of such constituents include potassium, creatine kinase, and protein. It can be generally assumed that any patient with significant crush injuries will have autoinfusion of hundreds of milliequivalents of potassium into the blood. There is no significant derangement in sodium levels, such as hypernatremia **(choice B)**, after a crush injury. Cells in general, and myocytes in particular, are storehouses of calcium. With significant myonecrosis, serum calcium can rise to dangerous levels, producing hypercalcemia, rather than hypocalcemia **(choice C)**. Hypoglycemia **(choice D)** would not be seen in this patient. Because of the stress of his injuries and the elevated levels of cortisol and epinephrine in his blood, massive amounts of glucose would be mobilized. Thus, if any derangement in glucose homeostasis were present, it would likely be hyperglycemia. Hyperphosphatemia, rather than hypophosphatemia **(choice E)**, is observed with a crush injury. Phosphate is an intracellular buffer that is also released from cells after necrosis and lysis.

Answer 21

Respuesta: D The **correct answer is D**. Acute mediastinitis with air in the tissues that occurs within a few hours of an upper gastrointestinal endoscopy is virtually diagnostic of instrumental, iatrogenic esophageal perforation. Boerhaave syndrome **(choice A)** is also a form of esophageal perforation, but it is caused by protracted, forceful vomiting, which this patient did not have. A dissecting aneurysm of the thoracic aorta **(choice B)** can mimic a myocardial infarction, but it would not fill the mediastinum with air. In upper gastrointestinal endoscopy, the esophagus, which has narrow lumen and a flimsy wall, can be perforated easily, but the stomach (choice C), which has ample lumen and a thick, strong wall, almost never is. Furthermore, other than looking, nothing was done that could damage the stomach (laser or electrocoagulation). Finally, a hole in the stomach gives an acute abdomen with free air under the diaphragm, rather than mediastinitis with air in the mediastinum. A real myocardial infarction (choice E) is rare in a 32-year-old, and like the previous option, it produces pain but not mediastinitis with air.

Answer 22

Respuesta: B The **correct answer is B**. A plain abdominal x-ray film is most likely to detect a stone in this patient, who manifests the typical symptomatology of renal colic, most commonly due to a urinary stone impacted in the ureter. Usually, gross or microscopic hematuria is present. Absence of fever is an important negative sign excluding coexistence of urinary tract infection. Most urinary stones consist of calcium phosphate or oxalate and thus contain enough calcium to be visible on plain xray films. However, some urinary calculi are radiolucent (especially uric and cystine stones), whereas others are so small as to be undetectable on plain x-ray films. Intravenous pyelography **(IVP; choice A)** is rarely necessary in patients with the typical presentation of renal colic. However, IVP becomes necessary when the diagnosis is uncertain. Frequently, this investigation will demonstrate dilatation of the ureter proximal to the site of stone blockage. Renal ultrasound examination **(choice C)** is useful when the stone is suspected to be located at the ureterovesical junction. The bladder should be full to allow ultrasonography. Serum calcium, phosphorus, electrolytes, and uric acid **(choice D)** should be evaluated in patients experiencing a first urinary tract stone, but serum chemistry studies are not necessary as initial diagnostic investigations. Urine cultures **(choice E)** are not necessary for uncomplicated urinary stone disease without clinical evidence of urinary tract infection. However, abnormal urinary pH should suggest participation of infectious agents in stone formation. Proteus infections result in alkaline pH because of urease production. On the other hand, a pH lower than 5.0 suggests urate or cystine stones.

Answer 23

Respuesta: E The **correct answer is E**. The description is perfect for simple liver cysts, which occur in roughly 10% of the population at large. Nothing needs to be done about this. The “Mexico connection” is the tip-off to suspect amebic abscess **(choice A)** in a patient who lives there and who presents with fever, leukocytosis, a tender liver, and elevated alkaline phosphatase. That is not the clinical picture this patient has, however. Cystadenocarcinomas **(choice B)** have thick walls with multiple septations. Calcifications in the cyst wall also may be present, and usually the affected patient is a middle-aged woman. Hydatid cysts **(choice C)** can occur but are not particularly prevalent in Mexico, a little geographic detail unknown to most American physicians. High plains in the Andes or a Mediterranean country would be a better location. In any event, however, the hydatid cyst is characteristic, with a large mother cyst containing daughter cysts around the periphery. The cysts of polycystic liver disease **(choice D)** occur in much larger numbers, tend to enlarge over the years, and often are accompanied by renal cysts.

Answer 24

Respuesta: J The **correct answer is J**. Secondary tuberculosis commonly affects the kidneys by hematogenous dissemination. Cavitary lesions may be demonstrated by intravenous pyelography (IVP). The patient frequently gives a history of weight loss and low-grade fever. The infection spreads with the urinary flow down into the bladder, frequently involving the epididymis and prostate in men. Sometimes, the first clinical manifestation of urinary tract tuberculosis is hematuria. Urine cultures are often negative, but the urine contains large numbers of leukocytes (so-called sterile pyuria).

Answer 25

Respuesta: F The **correct answer is F**. Hemorrhagic cystitis is characterized by marked hematuria, resulting from extensive erosions of the urinary bladder mucosa. Cyclophosphamide is one of the most common etiologic agents of this form of cystitis. Another cause of hemorrhagic cystitis is radiation.

Answer 26

Respuesta: M The **correct answer is M**. Von Hippel-Lindau syndrome is a hereditary autosomal dominant disease characterized by hemangioblastomas of the CNS (most frequently in the cerebellum and retina), cysts of the pancreas and kidneys, and renal cell carcinoma. The patient’s family history is perfectly compatible with this diagnosis. Thus, the presence of hematuria, along with coexistent renal lesions detected on ultrasonography, indicates that renal cell carcinoma has also developed in this patient. Renal cell carcinoma associated with von Hippel-Lindau syndrome is often multicentric and cystic. Recall that the gene involved in this disease (VHL gene) has been found mutated in most cases of the more common sporadic renal cell carcinoma. Acute postinfectious glomerulonephritis **(choice A)** manifests with nephritic syndrome, characterized by hematuria, hypertension, proteinuria less than 3 g/day, and mild edema (periorbital and pedal). It usually occurs in children 1-3 weeks following group A Streptococcus pharyngitis or impetigo. Autosomal dominant polycystic kidney disease **(choice B)** manifests in middle-aged or elderly individuals with hematuria and hypertension. Usually, palpable enlarged kidneys are found on physical examination. Bacterial cystitis **(choice C)** is commonly due to Escherichia coli. Dysuria, frequency of urination, and suprapubic discomfort are the principal symptoms. Hematuria, gross or microscopic, is frequently seen on dipstick urinalysis. Berger disease **(choice D)** is the most frequent cause of glomerulonephritis, manifesting with hematuria and/or proteinuria. It is often discovered incidentally. IgA deposition in the mesangium and high serum IgA levels are the defining features. Bladder transitional cell carcinoma **(choice E)** is associated with hematuria, but usually not with other symptoms. Intravenous pyelography (IVP) is not sensitive enough to detect this type of cancer. Urinary cytology and cystoscopy are necessary for diagnosis. Prostatic carcinoma **(choice G)** rarely manifests with hematuria as its first presenting sign. The most common mode of presentation nowadays is by elevated prostatic-specific antigen (PSA) and/or abnormal findings on digital rectal examination. Testicular cancer **(choice H)** is not associated with hematuria. Its most common first sign is painless testicular enlargement, associated with a sensation of heaviness. Frequently, patients come to the physician many months after the initial onset of these signs. Transitional cell carcinoma of the pelvis **(choice I)** is relatively rare compared with renal cell carcinoma and urinary bladder transitional carcinoma. Its most common presentation is hematuria, but IVP demonstrates these tumors as filling defects in the pelvicaliceal system. A ureteral stone **(choice K)** most commonly presents with renal colic, a paroxysmal form of flank pain associated with extreme restlessness that results from ureteral obstruction. Hematuria is present during colicky episodes and sometimes in asymptomatic periods. IVP would show dilatation of the ureter proximal to the impacted stone. Urethral carcinoma **(choice L)** usually comes to medical attention because of bloody urethral discharge in an elderly patient. If hematuria is present, it is detected in the first few milliliters of urine (initial hematuria) when urine is collected in separate aliquots.