Diverticular disease can cause significant bleeding. The condition most frequently responsible for a major hemorrhage is the presence of the pouches themselves, known as diverticulosis. Bleeding is a common complication of diverticular disease, though the risk remains relatively low for any single patient. While diverticulitis, the inflammation of these pouches, can sometimes involve blood, it is rarely the source of massive, acute bleeding that requires urgent medical attention.
Diverticular Disease: Diverticulosis Versus Diverticulitis
Diverticulosis is defined by the presence of small, bulging sacs, called diverticula, that push outward through weak spots in the wall of the large intestine (colon). This condition is extremely common, affecting a large percentage of the population over age 60, and often remains asymptomatic. Diverticulitis occurs when one or more of these pouches become inflamed or infected, typically causing symptoms like severe abdominal pain, fever, and a change in bowel habits.
The vast majority of severe lower gastrointestinal bleeding associated with diverticular disease is a complication of diverticulosis, not diverticulitis. When diverticulitis is present, any bleeding is usually minor or microscopic, resulting from the inflammatory process. The substantial, acute hemorrhage that requires emergency care arises from the uninflamed pouches of diverticulosis, highlighting that the mechanism of bleeding is primarily mechanical and structural.
How Bleeding Occurs
The formation of a diverticulum involves the herniation of the colon’s inner lining through the muscular layer of the wall. This creates a structural vulnerability where small blood vessels, known as the vasa recta, penetrate the muscular layer to supply the inner wall. As the pouch forms, the vasa recta vessel becomes stretched over the dome or neck of the diverticulum, separated from the intestinal lumen only by a thin layer of tissue.
Chronic trauma from the passage of stool and high pressure within the colon, often due to straining, can cause structural changes in this exposed vessel, weakening the vessel wall. Eventually, this high-pressure vessel ruptures into the colon, resulting in profuse bleeding. The bleeding is typically arterial because the vasa recta are terminal branches of the superior and inferior mesenteric arteries, which is why the hemorrhage is frequently massive and sudden.
Recognizing the Signs of Bleeding
Bleeding from a diverticulum is characterized by a sudden onset of large-volume rectal hemorrhage, known as hematochezia. This bleeding is typically painless because the mechanism is vascular rupture, not inflammation. The blood passed is usually bright red or maroon in color, and it may be mixed with dark, gelatinous clots.
The quantity of blood loss can be substantial, with diverticular hemorrhage accounting for a large percentage of severe lower gastrointestinal bleeding cases. Patients may experience systemic symptoms signaling significant blood volume loss, including lightheadedness, dizziness, and weakness, especially when standing up. Severe hemorrhage can lead to acute signs of shock, such as a rapid heart rate and dangerously low blood pressure, indicating a need for urgent resuscitation.
Stopping the Bleeding
In a majority of cases, the bleeding from a diverticulum stops spontaneously, with estimates ranging from 70% to 80% of episodes resolving without intervention. However, patients with persistent or heavy bleeding require prompt stabilization, which involves resuscitation with intravenous fluids and, if necessary, blood transfusions. The next step is to locate and stop the hemorrhage using minimally invasive techniques.
Colonoscopy is often the initial procedure of choice, allowing a specialist to view the colon lining and identify the specific bleeding site. If the source is found, endoscopic treatments such as injecting the area with epinephrine, applying clips, or using thermal coagulation can be used to stop the flow. If colonoscopy fails to control the hemorrhage, or if the bleeding is too rapid to visualize, angiography may be performed. This procedure involves threading a catheter into the bleeding artery and injecting material to block the vessel, a process called embolization. Surgery to remove the affected segment of the colon is reserved for cases where bleeding cannot be controlled by non-surgical methods or when the patient’s condition is unstable.