Diverticular bleeding is the most common cause of significant lower gastrointestinal bleeding, representing a serious health event for many individuals. This bleeding originates from diverticula, which are small, pouch-like herniations that form in the wall of the colon. While the presence of these pouches, a condition known as diverticulosis, is often harmless, bleeding occurs when a small blood vessel inside one of the pouches ruptures. Understanding the mechanism and potential severity of this event is crucial for managing the immediate danger and preventing future episodes.
What Causes Diverticular Bleeding
Diverticula typically form where small blood vessels, called the vasa recta, penetrate the muscular layer of the colon wall. High pressure inside the colon, often associated with a low-fiber diet and straining, causes the inner layers of the wall to push outward through these weak spots, creating the pouch. This outward bulging stretches the vasa recta over the dome or neck of the newly formed diverticulum.
The chronic stretching exposes the vessel to injury, causing structural weakening that makes it susceptible to rupture. This leads to the characteristic painless, brisk bleeding seen in diverticular hemorrhage. The bleeding event is usually not associated with inflammation, which distinguishes it from diverticulitis. Bleeding from right-sided diverticula is more common, possibly due to their wider necks and the thinner nature of the right colon wall.
The Immediate Risk and Severity Assessment
Diverticular bleeding can be dangerous because the hemorrhage is arterial, meaning blood loss can be massive and sudden. Patients typically notice a large volume of bright red or maroon blood passed through the rectum, often without any associated pain. Most episodes, estimated at 70% to 80% of cases, stop spontaneously without the need for medical intervention.
However, a significant minority of patients experience severe, life-threatening blood loss that requires emergency medical attention. Signs of severe hemorrhage include symptoms of hypovolemic shock, such as a rapid heart rate, low blood pressure, dizziness, or fainting when standing up. These symptoms indicate the body is struggling to compensate for the rapid loss of blood volume.
The severity is assessed by checking for hemodynamic instability and the need for blood transfusions. Patients who present with a low hemoglobin level or require a significant blood transfusion are classified as having severe bleeding. Older age and underlying health conditions like chronic kidney disease can also increase the risk of a severe episode.
Treatment Options to Control Acute Bleeding
For cases where the bleeding does not stop on its own, immediate intervention is necessary to achieve hemostasis. Colonoscopy is typically the first-line diagnostic and therapeutic procedure, performed after the patient is stabilized. During the colonoscopy, the physician attempts to locate the specific bleeding diverticulum, which is then treated with various endoscopic techniques.
These techniques include applying metal clips directly to the bleeding vessel, using endoscopic band ligation to cut off the blood supply, or employing thermal coagulation (heat) or injection of a vasoconstrictive agent like epinephrine. Endoscopic methods are successful in the majority of active bleeding cases.
If endoscopic treatment fails, or if the bleeding is too rapid for effective visualization, a procedure called transcatheter arterial embolization (TAE) may be used. This involves an interventional radiologist guiding a catheter to the bleeding site to inject material that blocks the vessel. Surgical resection of the affected part of the colon is reserved as a last resort for patients with persistent, uncontrolled bleeding or those too unstable for less invasive procedures.
Long-Term Management to Reduce Recurrence
Once the acute bleeding is controlled, the focus shifts to preventing future recurrences. Diverticular bleeding has a significant risk of rebleeding, with recurrence rates reported to be as high as 20% to 42% over one to two years. This risk is higher in individuals with chronic health issues or a history of previous bleeding.
Management primarily involves lifestyle modifications aimed at lowering colon pressure and improving bowel health. Increasing dietary fiber is the most recommended change, as this helps create bulkier, softer stools that pass more easily. Adequate hydration also supports this goal by preventing constipation.
Patients are advised to avoid non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin when possible, as these medications increase the risk of bleeding. For those who have experienced severe or recurrent episodes, managing underlying conditions like hypertension or chronic kidney disease is an important part of the long-term strategy.