A 72-year-old man develops mild abdominal pain and bloody diarrhea after undergoing urgent cholecystectomy. The surgery was complicated by an episode of hypotension that was treated with bolus intravenous crystalloid fluids. The patient had no previous gastrointestinal bleeding. His last colonoscopy 10 years ago was normal. Past medical history is notable for hypertension, hyperlipidemia, type 2 diabetes mellitus, and a myocardial infarction 7 years ago. The patient smoked for 40 years and quit after the myocardial infarction. Colonoscopy would most likely show pathology in which of the following portions of the large bowel?

Question

A 72-year-old man develops mild abdominal pain and bloody diarrhea after undergoing urgent cholecystectomy.  The surgery was complicated by an episode of hypotension that was treated with bolus intravenous crystalloid fluids.  The patient had no previous gastrointestinal bleeding.  His last colonoscopy 10 years ago was normal.  Past medical history is notable for hypertension, hyperlipidemia, type 2 diabetes mellitus, and a myocardial infarction 7 years ago.  The patient smoked for 40 years and quit after the myocardial infarction.  Colonoscopy would most likely show pathology in which of the following portions of the large bowel?

Quizplus · Accepted Answer

11ec160b_3937_ebc2_9249_1b70e03e183f_MD0001_00 This patient with abdominal pain and bloody diarrhea following a complicated surgical procedure likely has acute nonocclusive ischemic colitis. The colon receives blood from the marginal artery of the colon (artery of Drummond), an anastomotic system of arteries that is in turn supplied by the superior (SMA) and inferior (IMA) mesenteric artery systems. The distal colon receives blood also from the internal iliac artery. In low-flow states, as may be seen in severe hypotension in patients with underlying arterial insufficiency (eg, diabetes, atherosclerotic arterial disease), nonocclusive ischemia may occur at the margins of the anastomotic distributions. These "watershed" areas are primarily in the left colon at the splenic flexure (border between SMA and IMA supply) and rectosigmoid junction (border between sigmoid artery and superior rectal artery). Less commonly, occlusive ischemia can also be caused by thromboembolic (eg, hypercoagulable states, atrial fibrillation) or atheroembolic (eg, aortic instrumentation) events. Impaired perfusion to the bowel leads to ischemia and necrosis of the intestinal wall. Complications can include acidosis, sepsis, gangrene, and perforation. Colonoscopy will reveal pale mucosa and petechial hemorrhages. (Choices A, B, C, and E) The ascending colon, cecum, hepatic flexure, and most of the transverse colon are supplied by branches of the SMA. Mesenteric ischemia in these areas is significantly less common than in the watershed areas of the left colon. Ischemia is also uncommon in the rectum, which receives collateral blood supply via the rectal arteries. Educational objective: The splenic flexure and rectosigmoid junction lie between regions of perfusion of major arteries. These "watershed" areas are susceptible to ischemic damage during hypotensive states, especially in patients with underlying arterial insufficiency. __________ References: Clinical approach to colonic ischemia. (http://www.ncbi.nlm.nih.gov/pubmed/19570972)

A 72-Year-Old Man Develops Mild Abdominal Pain and Bloody Diarrhea