Diverticular hemorrhage is the most common cause of colonic bleeding, accounting for 20%-65% of cases of severe lower intestinal bleeding in adults.1 Urgent colonoscopy after purging the colon of blood, clots, and stool is the most accurate method of diagnosing and guiding treatment of definitive diverticular hemorrhage.2-5 The diagnosis of definitive diverticular hemorrhage depends upon identification of some stigmata of recent hemorrhage (SRH) in a single diverticulum (TIC), which can include active arterial bleeding, oozing, non-bleeding visible vessel, adherent clot, or flat spot.2-4 Although other approaches, such as nuclear medicine scans and angiography of various types (CT, MRI, or standard angiography), for the early diagnosis of patients with severe hematochezia are utilized in many medical centers, only active bleeding can be detected by these techniques. However, as subsequently discussed, this SRH is documented in only 26% of definitive diverticular bleeds found on urgent colonoscopy, so diagnostic yields of these techniques will be low.2-5
The diagnosis of patients with severe hematochezia and diverticulosis, as well as triage of all of them to specific medical, endoscopic, radiologic, or surgical management, is facilitated by an urgent endoscopic approach.2-5 Patients who are diagnosed with definitive diverticular hemorrhage on colonoscopy represent about 30% of all true TIC bleeds when urgent colonoscopy is the management approach.2-5 That is because approximately 50% of all patients with colon diverticulosis and first presentation of severe hematochezia have incidental diverticulosis; they have colonic diverticulosis, but another site of bleeding is identified as the cause of hemorrhage in the gastrointestinal tract.2-4 Presumptive diverticular hemorrhage is diagnosed when colonic diverticulosis without TIC stigmata are found but no other GI bleeding source is found on colonoscopy, anoscopy, enteroscopy, or capsule endoscopy.2-5 In our experience with urgent colonoscopy, the presumptive diverticular bleed group accounts for about 70% of patients with documented diverticular hemorrhage (e.g., not including incidental diverticulosis bleeds but combining subgroups of patients with either definitive or presumptive TIC diagnoses as documented TIC hemorrhage).
Patients with diverticular hemorrhage present with severe, painless large volume hematochezia. Hematochezia may be self-limited and spontaneously resolve in 75%-80% of all patients but with high rebleeding rates up to 40%.5-7 Of all patients with diverticulosis, only about 3%-5% develop diverticular hemorrhage.8 Risk factors for diverticular hemorrhage include medications (e.g., nonsteroidal anti-inflammatory drugs – NSAIDs, antiplatelet drugs, and anticoagulants) and other clinical factors, such as older age, low-fiber diet, and chronic constipation.9,10 On urgent colonoscopy, more than 70% of diverticulosis in U.S. patients are located anatomically in the descending colon or more distally. In contrast, about 60% of definitive diverticular hemorrhage cases in our experience had diverticula with stigmata identified at or proximal to the splenic flexure.2,4,11
Colonic diverticula are herniations of mucosa and submucosa with colonic arteries that penetrate the muscular wall. Bleeding can occur when there is asymmetric rupture of the vasa recta at either the base of the diverticulum or the neck.4 Thinning of the mucosa on the luminal surface (such as that resulting from impacted fecaliths and stool) can cause injury to the site of the penetrating vessels, resulting in hemorrhage.12