A 65-year-old man is admitted with rectal bleeding. He noticed a significant amount of blood in the toilet after going to the bathroom this morning and had some mild cramping just before that bowel movement. His past medical history is positive for coronary artery disease (has had stents placed and is on aspirin and clopidogrel) and osteoarthritis for which he has been taking ibuprofen. He denies weight loss and has no previous history of bleeding. On examination he is slightly diaphoretic. Vital signs are BP 124/72 and pulse 88 with the patient supine, BP 94/52 and pulse 110 with the patient standing. Abdomen is nontender and nondistended. NG aspirate is negative for occult blood. After establishing two large-bore intravenous lines, administering an IV fluid bolus and otherwise stabilizing the patient, what will be the most important study to perform?
A. Upper endoscopyThis patient has ischemic colitis. It typically occurs in people older than 50. Risk factors include atherosclerotic disease, including peripheral vascular disease and coronary artery disease. Episodes of bleeding can be preceded by abdominal pain and watery diarrhea. Colonoscopy will reveal inflammatory changes (sometimes patchy) from the splenic flexure to the sigmoid colon with sparing of the rectum. Nonsteroidal induced colitis is also a possibility and could be evaluated by colonoscopy. Given the history of red blood per rectum, upper endoscopy would not be the first choice of examination. An air-contrast barium enema could be obtained if colonoscopy were unavailable, in order to evaluate for colitis and to rule out a carcinoma. Plain x-rays of the abdomen occasionally show thumbprinting from edematous mucosal folds but are less sensitive than colonoscopy. A CT of the abdomen would be unrevealing in a case of ischemic colitis and would be unlikely to detect a small carcinoma if present.