Diverticular bleeding is painless rectal bleeding originating from a diverticulum, a small pouch protruding from the colon wall. It is a complication of diverticulosis (the presence of these pouches) and is the most frequent cause of lower gastrointestinal bleeding. While the bleeding often resolves without medical intervention, it can present as a massive, life-threatening hemorrhage. Any instance of diverticular bleeding should be treated as a medical emergency requiring immediate evaluation and management.
Understanding Diverticular Bleeding
Diverticula are acquired sac-like protrusions of the inner lining of the colon through weak points in the muscular wall. These weak points occur where small blood vessels, known as the vasa recta, penetrate the muscle layer to supply blood to the inner wall. The formation of these pouches causes the vasa recta to become draped over the dome of the diverticulum, separated from the colon’s interior only by a thin layer of mucosa.
The mechanism of bleeding involves chronic injury or abrasive factors, such as hardened stool, causing erosion to the blood vessel wall. This erosion leads to a thinning of the vessel’s media layer and a thickening of the intima, creating a segmental weakness in the artery. The resulting asymmetric rupture of the vasa recta at the dome of the diverticulum causes sudden, large-volume, painless bleeding into the colon. This bleeding occurs in the absence of inflammation, distinguishing it from the complications of diverticulitis.
Assessing the Danger and Severity
Diverticular bleeding presents a wide spectrum of severity, which directly influences the danger it poses. The bleed is characterized by the passage of a large volume of bright red or dark maroon blood, generally not accompanied by abdominal pain. While a majority of episodes (70% to 80%) stop spontaneously, the remaining cases can be severe and potentially life-threatening.
The danger escalates with the volume and speed of blood loss, which can rapidly lead to hypovolemia. Signs of severe bleeding include symptoms of shock, such as a rapid heart rate, low blood pressure, and dizziness or fainting upon standing. Patients older than 60 or those with pre-existing conditions like cardiovascular disease face a higher risk of complications. Severe hemorrhage often necessitates immediate blood transfusions to replace lost volume. The morbidity and mortality rate for patients experiencing uncontrolled diverticular bleeding is reported to be between 10% and 20%.
Stopping the Bleed: Emergency Treatment
The acute medical response begins with immediate patient stabilization, particularly for those with massive hemorrhage. This involves establishing intravenous access, typically with two large-bore IV lines, to administer fluids and correct hemodynamic instability. Blood transfusions are often initiated promptly to restore blood volume and oxygen-carrying capacity, especially if laboratory tests show significant anemia.
The primary diagnostic and therapeutic procedure is an urgent colonoscopy, ideally performed within 24 hours of admission after a rapid bowel preparation. Colonoscopy allows the physician to visualize the colon’s interior and locate the bleeding diverticulum, identified by signs of recent hemorrhage. If the source is found, several endoscopic techniques can be used to stop the bleeding, including the injection of epinephrine, thermal coagulation, or the application of endoscopic clips or bands.
If colonoscopy fails to locate or control the bleed, the next intervention is typically angiography. This procedure involves injecting a contrast dye into the arteries to pinpoint the actively bleeding vessel. Once localized, the vessel can be treated with transcatheter arterial embolization, where tiny particles are injected to mechanically block the blood flow. Surgery, specifically a segmental colectomy to remove the affected part of the colon, is reserved as a last resort for uncontrolled bleeding that persists despite failed endoscopic and angiographic attempts.
Long-Term Management and Prevention
Once the acute bleeding episode is resolved, long-term management focuses on preventing recurrence by addressing the underlying diverticulosis. Dietary modification is a primary preventative strategy, centered on incorporating a high-fiber diet. Fiber helps to increase stool bulk and soften its consistency, which reduces the pressure exerted inside the colon during bowel movements.
This reduction in intraluminal pressure minimizes strain on the colon wall, lessening the risk of further injury to the vasa recta within the diverticula. Patients are advised to consume high-fiber foods such as fruits, vegetables, and whole grains, and to ensure adequate hydration. A review of medications is also performed, as the use of nonsteroidal anti-inflammatory drugs (NSAIDs) and anticoagulants are known risk factors for future bleeding events.