A 64-year-old man with a history of coronary artery disease and peripheral vascular disease undergoes coronary artery bypass surgery. His postoperative course is complicated by hypotension, which is treated successfully with intravenous fluids; however, a few hours later, he experiences abdominal pain followed by bloody diarrhea. His temperature is 37.8 C (100 F), blood pressure is 110/60 mm Hg, pulse is 110/min, and respirations are 20/min. Abdominal examination shows normal bowel sounds, with no significant guarding or focal tenderness. Laboratory results are as follows: The venous lactic acid level is elevated. An abdominal CT scan is ordered. Which of the following areas will most likely show abnormal findings?

Question

A 64-year-old man with a history of coronary artery disease and peripheral vascular disease undergoes coronary artery bypass surgery.  His postoperative course is complicated by hypotension, which is treated successfully with intravenous fluids; however, a few hours later, he experiences abdominal pain followed by bloody diarrhea.  His temperature is 37.8 C (100 F), blood pressure is 110/60 mm Hg, pulse is 110/min, and respirations are 20/min.  Abdominal examination shows normal bowel sounds, with no significant guarding or focal tenderness.  Laboratory results are as follows:  The venous lactic acid level is elevated.  An abdominal CT scan is ordered.  Which of the following areas will most likely show abnormal findings?

Quizplus · Accepted Answer

11ec25c8_d8e7_a84f_bc81_7dc8e0adcc70_MD0003_00 This patient with acute abdominal pain followed by lower gastrointestinal bleeding after an episode of hypotension most likely has ischemic colitis. Fever, nausea, elevated lactic acid, and leukocytosis may also be seen. Older patients with atherosclerotic vascular disease are at particularly high risk. The most commonly involved segments of the colon include the splenic flexure at the "watershed" line between the territory of the superior and inferior mesenteric arteries and the rectosigmoid junction at the watershed between the sigmoid artery and superior rectal artery. superior and inferior mesenteric arteries Abdominal CT scan with intravenous contrast may show thickened bowel wall, although it may demonstrate only nonspecific findings. CT should be performed urgently to identify patients with ischemic colitis who need immediate surgical intervention (eg, extensive bowel damage, perforation). If colon resection is not needed, patients are treated with intravenous fluids and antibiotics and endoscopic evaluation (colonoscopy) is performed to confirm the diagnosis. Typical findings include pale mucosa with petechial bleeding, bluish hemorrhagic nodules, or cyanotic mucosa with hemorrhage. (Choice C) Small bowel (mesenteric) ischemia is usually due to atheroembolic (eg, endovascular procedures) or thromboembolic (eg, atrial fibrillation) events rather than acute hypotension. Pain is typically severe but is poorly localized and out of proportion to examination findings; hematochezia may occur but is a late finding. CT would show focal or segmental bowel wall thickening and mesenteric stranding. Educational objective: Ischemic colitis is characterized by acute abdominal pain and lower gastrointestinal bleeding. It typically follows an episode of hypotension and most commonly affects arterial watershed areas at the splenic flexure and rectosigmoid junction. CT scan may show a thickened bowel wall. Colonoscopy can confirm the diagnosis. References: Update on colon ischemia: recent insights and advances. (http://www.ncbi.nlm.nih.gov/pubmed/26446556)

A 64-Year-Old Man with a History of Coronary Artery Disease