A 70-year-old man is brought to the emergency department by his wife due to rectal bleeding. The patient initially had a bowel movement consisting of a large volume of bright red blood without associated abdominal pain. Since then, he has had persistent lightheadedness along with several urges to defecate in which blood is produced. The patient has no prior history of gastrointestinal bleeding. Past medical history is notable for hypertension and chronic constipation. Current medications include chlorthalidone and low-dose aspirin. Temperature is 36.5 C (97.8 F), blood pressure is 85/45 mm Hg, pulse is 120/min, and respirations are 20/min. The abdomen is soft, nondistended, and nontender; bowel sounds are normal. No masses or organomegaly are palpable. Rectal examination shows bright red blood. Nasogastric aspiration returns nonbilious stomach contents without blood. A plain radiograph of the abdomen is normal. Which of the following is the most likely cause of this patient's bleeding?

Question

A 70-year-old man is brought to the emergency department by his wife due to rectal bleeding.  The patient initially had a bowel movement consisting of a large volume of bright red blood without associated abdominal pain.  Since then, he has had persistent lightheadedness along with several urges to defecate in which blood is produced.  The patient has no prior history of gastrointestinal bleeding.  Past medical history is notable for hypertension and chronic constipation.  Current medications include chlorthalidone and low-dose aspirin.  Temperature is 36.5 C (97.8 F), blood pressure is 85/45 mm Hg, pulse is 120/min, and respirations are 20/min.  The abdomen is soft, nondistended, and nontender; bowel sounds are normal.  No masses or organomegaly are palpable.  Rectal examination shows bright red blood.  Nasogastric aspiration returns nonbilious stomach contents without blood.  A plain radiograph of the abdomen is normal.  Which of the following is the most likely cause of this patient's bleeding?

Quizplus · Accepted Answer

This patient has large-volume rectal bleeding most likely due to diverticular hemorrhage. Diverticulosis is the most common cause of gross lower gastrointestinal (GI) bleeding in adults. Diverticula are outpouchings of the colonic wall that form at points of weakness. They can be seen on abdominal CT, but plain radiographs are typically normal. The deformation in the colonic wall can cause weakness in the associated arterial supply and lead to bleeding into the diverticular lumen. Diverticulosis is most common in the sigmoid colon, but diverticular bleeding is more common in the right colon. Diverticular bleeding is typically painless, but large-volume bleeding may be associated with lightheadedness and hemodynamic instability. Low- or moderate-volume bleeding from the right colon will mix with stool and pass as dark or maroon-colored stools. Large-volume hemorrhage can lead to passage of frank red blood. Irritation due to bleeding can cause an urge to defecate. The diagnosis is confirmed on colonoscopy (which is indicated in management of presumed diverticular bleed but contraindicated in diverticulitis due to inflamed diverticuli [eg, abdominal pain, low-grade fever]). Most cases of diverticular hemorrhage will resolve spontaneously, but a minority of patients will require endoscopic or surgical intervention. (Choice A) Colonic angiodysplasia can cause painless bleeding in the right colon. However, it is significantly less common than diverticular hemorrhage. In addition, because bleeding due to angiodysplasia is usually venous, it is typically low-volume, whereas diverticulosis can cause large-volume arterial hemorrhage. (Choice B) Colon cancer tends to cause chronic occult blood loss, with abdominal pain, altered passage of stool, and weight loss. Gross bleeding is less likely. (Choice D) Hemorrhoids cause painless rectal bleeding, with bright red blood in the toilet bowl or on the paper. However, it would be unusual for hemorrhoids to cause massive lower GI bleeding (eg, hypotension, lightheadedness). (Choice E) Ischemic colitis causes sudden onset of abdominal pain and tenderness, followed by rectal bleeding. It can occur due to inadequate perfusion of "watershed" areas of the colon (eg, splenic flexure) in the setting of nonocclusive ischemia or surgical or endovascular interventions. (Choice F) Acute mesenteric thrombosis presents with abdominal pain out of proportion to physical findings, nausea/vomiting, and bloody diarrhea due to mucosal sloughing. Patients have numerous atherosclerotic risk factors. (Choice G) Brisk upper GI bleeding (eg, due to peptic ulcer disease) can present with bright red blood per rectum; however, most patients with upper hemorrhage of that degree usually have hematemesis as well. This patient's nonbloody gastric aspirate makes an upper GI source less likely. Educational objective: Diverticulosis is the most common cause of gross lower gastrointestinal bleeding in adults. Bleeding is typically painless but may be associated with lightheadedness and hemodynamic instability. Diverticular hemorrhage usually resolves spontaneously but occasionally requires endoscopic or surgical intervention. References: Bleeding colonic diverticula. (http://www.ncbi.nlm.nih.gov/pubmed/18936658)

A 70-Year-Old Man Is Brought to the Emergency Department by His