A 63-year-old male is evaluated in the emergency department for an episode of painless bright red blood per rectum for 2 hours. The patient is known to have sigmoid diverticulosis, noted on colonoscopy 1 month ago. The patient’s bleed most likely arose from a distal branch of which of the following vessels?
- Superior mesenteric vein
- Super mesenteric artery
- Inferior mesenteric vein
4) Inferior mesenteric artery - Superior hemorrhoidal artery
explanation
This patient has a diverticular bleed. Diverticular bleeds are most commonly arterial, due to erosion of an artery by a diverticulum. As the sigmoid colon is supplied by the inferior mesenteric artery (IMA), a distal branch of this artery is most likely responsible for the arterial bleed.
Diverticular bleeding is the most common cause of lower GI hemorrhage. The typical presentation includes a painless flow of blood per rectum. While only about 15% of patients with diverticular disease have bleeding, one third of the bleeds will be massive. Erosion of an artery is the most common source of a diverticular bleed.
Illustration A shows the appearance of diverticulosis and diverticulitis (inflammed diverticula) on colonoscopy.
Illustration B shows the arterial blood supply to the colon.