Preguntas y Respuestas 5

Cirugía General

• Clinical Scenario 1. A 30-year-old man sustains blunt head trauma and is unconscious. His urine output exceeds 1,500 mL per hour despite only receiving maintenance intravenous fluids. He becomes profoundly hypernatremic. Which of the following is the next step in the initial management of this patient?

• Answer. This patient has blunt head trauma and diabetes insipidus, characterized by high volume, low osmolality urine. This, untreated, may result in profound dehydration and hypernatremia. Treatment is conservative, with replacement of free water intravenously

• Clinical Scenario 5. A 20-year-old woman presents after a skiing accident. She is alert and talking but not moving. Her blood pressure is 80/55 mm Hg, and her pulse is 80 beats/minute. What is the etiology of her shock, and what should the workup include to aid in the diagnosis?

• Answer. Neurogenic shock from a probable cervical spine fracture. Workup should include a complete spine evaluation.

• Clinical Scenario 23. A 39-year-old woman complains of right upper quadrant pain. She also has nausea and fatigue. She has a history of ulcerative colitis. Physical examination reveals icteric sclera. Laboratory studies reveal elevated transaminases. What is the next step in the management of this patient?

• Answer. This patient likely has primary sclerosing cholangitis. This condition results in stenosis or obstruction of the ductal system. ERCP may reveal thickening and stenosis of the biliary ductal system.

• Clinical Scenario 59. A 45-year-old man who smokes presents with progressively increasing cough, sputum production, and fever for the past 4 days. In the past day he has also noticed the development of right upper quadrant abdominal pain. On examination, he has diminished breath sounds at the right base, with dullness to percussion. Abdominal examination shows minimal tenderness in the right upper quadrant, with no Murphy sign. What is the diagnosis?

• Answer. He most likely has a right lower lobe pneumonia irritating his diaphragm, which is leading to his right upper quadrant pain.

• Clinical Scenario 63. A 23-year-old man is seen in the emergency department after a motor vehicle accident. He was an unrestrained passenger. He is able to breathe on his own but tells you that each breath is extremely painful. You note that a segment of his chest wall appears to sink inwards with each respiration, and that when he exhales this same segment does not move with the rest of the chest wall. Vital signs are stable. The patient has no other obvious traumatic injuries. The arterial blood gas reads as follows: 7.3/55/85/25. What is the most appropriate next step in management?

• Answer. This describing flail chest. This occurs when four or more ribs are fractured in at least two locations, leading to paradoxical movement of the chest wall during respiration. This commonly occurs after trauma such as a motor vehicle accident. The true danger in patients with flail chest is the frequent underlying pulmonary contusion.• In this patient we see a blood gas indicative of a decreased respiratory

effort, suggesting that he is not properly respiring. We would need to inubate this patient and provide mechanical ventilation in light of the marked respiratory distress.

• Clinical Scenario 20. A 73-year-old woman undergoes a computed tomography (CT) scan for abdominal pain and is found to have thickening of the terminal ileum. She is also noted to have multiple mesenteric lymph nodes that are enlarged to more than 2 cm. A colonoscopy is performed that shows no abnormalities of the colon, but when the terminal ileum is entered, a friable intraluminal mass is encountered. The biopsies of this mass are read as diffuse large cell non-Hodgkin lymphoma. Positron emission tomography and CT confirm involvement of the terminal ileum but are also read as showing multiple mediastinal nodes involved with the disease. Bone marrow aspiration is negative for lymphoma. • Should this patient undergo a wide resection of the diseased terminal ileum

prior to starting chemotherapy?

• Answer. No. The patient has stage III non-Hodgkin lymphoma and should be treated with chemotherapy and possibly radiotherapy to the mediastinum. The only indication for surgical exploration in this patient would be if she should start bleeding from the terminal ileum or if the involved area should perforate.

• Clinical Scenario 16. A 25-year-old man presents to the emergency department with a history of 6 months of variable right lower quadrant abdominal pain, which acutely worsened over the past 12 hours so that he now rates it as 8 on a scale of 10, with 10 being the most painful. He also reports that he has been having diarrhea and low back pain for about 3 months. Computed tomography scan shows stranding of the mesentery in the right lower quadrant. On insertion of a laparoscope, you note that the terminal ileum and cecum are markedly inflamed, with some fat wrapping of the terminal ileum, although the appendix appears normal. • What is your next step in this operation?

• Answer. Close the camera incision and treat the patient for Crohn disease. Even if the base of the cecum is uninvolved, appendectomy is contraindicated in the presence of Crohn disease due to an unacceptably high rate of enterocutaneous fistulization.

• A 30-year-old man consults a physician because he has been having increasing difficulty swallowing both solids and liquids. Physical examination of the patient is noncontributory. Barium swallow studies show a mostly dilated esophagus with slow passage of barium into the stomach. The very distal part of the esophagus appears narrowed into a "bird's beak." Esophageal manometry shows incomplete relaxation of the lower esophageal sphincter in response to swallowing, high resting lower esophageal pressure, and absent esophageal peristalsis.

• Question 1 of 5. The manometry and barium swallow studies most strongly support which of the following diagnoses?

• / A. Achalasia• / B. Adenocarcinoma• / C. Barrett esophagus• / D. Squamous cell carcinoma• / E. Systemic sclerosis

• The correct answer is A. The most likely diagnosis is achalasia. This condition is a neurogenic esophageal disorder that can occur at any age, but frequently is diagnosed when individuals are between the ages of 20 and 40. Characteristically, the swallowing difficulties involve both solid food and liquids. The manometry findings illustrated are typical; the barium swallow findings may be as illustrated or may instead show diffuse esophageal dilation without the "bird's beak" near the lower esophageal sphincter.

• Question 2 of 5. This patient's condition is most likely due to which of the following?• / A. Acid reflux• / B. Cancerous destruction• / C. Candida infection• / D. Fibrosis of the esophageal wall• / E. Lack of ganglion cells

• The correct answer is E. Individuals who have achalasia have been found to have a deficiency of inhibitory ganglion cells within the esophageal wall. This lack causes an imbalance in excitatory and inhibitory neurotransmission, with the result that the lower esophageal sphincter tends to have a higher-than-normal muscle tone and relaxes only with difficulty.

• Question 3 of 5. Which of the following regulators would most likely inhibit the lower esophageal sphincter in normal individuals?• / A. Acetylcholine and substance P• / B. Substance P and nitric oxide• / C. Substance P only• / D. Vasoactive intestinal polypeptide and acetylcholine• / E. Vasoactive intestinal polypeptide and nitric oxide

• The correct answer is E. Physiologically important inhibitors of the lower esophageal sphincter include nitric oxide and vasoactive intestinal polypeptide. Physiologically important substances that stimulate the lower esophageal sphincter include acetylcholine and substance P.

• Question 4 of 5. Which of the following medications is used to directly relax the lower esophageal sphincter?• / A. Diphenoxylate• / B. Famotidine• / C. Granisetron• / D. Isosorbide dinitrate• / E. Metoclopramide

• The correct answer is D. Commonly used medications to relax the lower esophageal sphincter in patients with achalasia include nitrates such as isosorbide dinitrate (remember that nitric oxide physiologically inhibits the lower esophageal sphincter) and calcium channel blockers such as nifedipine (which inhibit calcium flow into the smooth muscle of the lower esophageal sphincter, thereby inhibiting contraction.) For patients in whom medical therapy fails, other options include paralysis of the lower esophageal sphincter with intrasphincteric injection of botulinum toxin, pneumatic dilatation, and a Heller myotomy (which interrupts the muscles of the lower esophageal sphincter).

• Question 5 of 5. Worldwide, which of the following parasitic diseases is most likely to produce a disorder that clinically resembles this patient's condition?• / A. Ascariasis• / B. African sleeping sickness• / C. Chagas disease• / D. Cysticercosis• / E. Malaria

• The correct answer is C. Chagas disease, which is found in South and Central America and is due to infection with Trypanosoma cruzi, can involve the heart, colon, and esophagus. The esophageal involvement clinically closely resembles achalasia.

• A 35-year-old woman consults a physician because she has been having trouble swallowing. She also often experiences chronic heartburn. The physician performs a screening physical examination, and notices that the skin of her hands appears tight and shiny. On specific questioning, she reports having often experienced color changes in her hands from white to blue to red.

• Question 1 of 5. Which of the following is the most likely cause of the patient's difficulties with swallowing?

• A. Achalasia• B. Adenocarcinoma• C. Chagas disease• D. Scleroderma• E. Squamous carcinoma

• The correct answer is D. The tip-off is the reference to the patient's skin changes that are typical for scleroderma, also known as systemic sclerosis. Scleroderma is a disease that may be either predominately limited to the skin or involve many body systems, including the musculoskeletal system, gastrointestinal tract (with esophageal involvement most often symptomatic), cardiorespiratory system, and renal system. Esophageal dysfunction is a common complication of scleroderma. In most patients, the skin changes are obvious, even if the patient has not been previously diagnosed. Rarely, the skin changes may be noticed at an earlier stage, in which the skin of the hands appears puffy and edematous, but not scarred.

• Question 2 of 5. The color changes described on the patient's hand are most likely due to which of the following?• / A. Arteriolar spasm• / B. BIood clots at sites of vascular injury• / C. Large artery spasm• / D. PIatelet clots• / E. Stasis blood clots

• The correct answer is A. The color changes described are typical for Raynaud's phenomenon, which occurs because of changes in perfusion due to arteriolar spasm. Raynaud's phenomenon is common in scleroderma, largely because the subintimal hyperplasia of small vessels characteristic of scleroderma can reduce the luminal diameter by more than 75%. Some authors argue that the vascular changes seen in scleroderma are actually the insult that triggers the subsequent development of fibrosis.

• Question 3 of 5. Additional findings on physical examination include noting that the skin changes are limited to areas distal to the elbow and knee, the presence of calcified nodules on the extensor surfaces of the forearms, and the presence of telangiectasias on the forearms. This suggests that this patient has which of the following?• / A. Bauer syndrome• / B. Charcot syndrome• / C. CREST syndrome• / D. Crigler-Najjar syndrome• / E. Dandy-Walker syndrome

• The correct answer is C. These findings, together with esophageal dysfunction and Raynaud's phenomenon (both of which this patient has), are called the CREST syndrome, also known as limited cutaneous scleroderma. This form of scleroderma has a better long-term prognosis than when the skin changes also involve the trunk (diffuse scleroderma) and more internal organs are additionally involved.

• Question 4 of 5. If this woman's involved skin were biopsied, which of the following would most likely be seen?• / A. CIeft separating the dermis and subcutaneous tissues• / B. Epithelial cell hyperplasia• / C. Marked dermal fibrosis• / D. Narrowing of the basal lamina of small capillaries• / E. Thickening of rete pegs

• The correct answer is C. In scleroderma, early changes (at the point at which the hands appear swollen, rather than with tight, thick skin) show edema with perivascular infiltrates of CD4+ T cells. At this stage, the collagen fibers are swollen and beginning to degenerate. The smaller vessels may show basal lamina thickening (not narrowing as in choice D) and endothelial (not epithelial as in choice B) cell damage and proliferation. With time, the characteristic marked dermal fibrosis develops, which tends to both narrow (not thicken as in choice E) the rete pegs and attach the dermis tightly (compare with cleft formation as in choice A) to subcutaneous tissues.

• Question 5 of 5. More than 90% of the patients with the limited cutaneous form of this disorder make which of the following autoantibodies?• / A. Anti-centromere• / B. Anti-DNA topoisomerase l• / C. Anti-double-stranded DNA• / D. Anti-Golgi• / E. Anti-ScI-70

• The correct answer is A. All forms of scleroderma are thought to have a strong autoimmune component, and glucocorticoids and azathioprine are used to suppress the inflammatory complications of scleroderma. (Other drugs that can be used in therapy include penicillamine, which inhibits collagen cross-linking, NSAIDS for pain, and ACE inhibitors to protect the kidney if hypertension or renal damage occurs.) The anti-centromere antibody is quite specific for CREST syndrome (96% of cases), and is only seen in a minority of patients with diffuse scleroderma (mainly those with Raynaud's phenomenon) and rarely in systemic lupus erythematosus and mixed connective tissue disease.