Chapter 19-6: Diverticular Bleed

TEXTBOOK PRESENTATION

The typical presentation is an episode of bright red blood per rectum in an older patient. There may be abdominal cramping but no real pain. A history may include previously diagnosed diverticuli (on a screening colonoscopy, for instance) and possibly a previous, self-limited hemorrhage.

DISEASE HIGHLIGHTS

1. Diverticular bleeds are the most common cause of lower GI bleeding.

   1. The prevalence of the various causes of GI bleeding varies from study to study.

   2. One large review gave the following data:

      1. Diverticulosis: 35%

      2. Inflammatory bowel disease (IBD) or other colitis: 14%

      3. Colonic malignancy or polyp: 7%

      4. Angiodysplasia: 3%

      5. Anorectal cause: 12%

2. The risk of diverticular hemorrhage in a patient with diverticuli is not known but is estimated to be 3–15%.

3. Data from case-control studies suggest that nonsteroidal anti-inflammatory drug (NSAID) use and hypertension are risk factors for diverticular hemorrhage.

4. Although diverticula are most commonly left sided, right-sided lesions are responsible for most bleeding episodes.

5. Bleeding occurs as a vessel is stretched over the dome of a diverticulum. Luminal trauma likely leads to bleeding from the weakened vessel.

6. Spontaneous cessation and only moderate blood loss is the rule, but recurrence is common.

   1. About 75% of patients experience spontaneous cessation of hemorrhage.

   2. Nearly all patients require < 4 units of packed red blood cells.

   3. Approximately 40% of patients have recurrent bleeding.

7. Diverticular hemorrhage carries a poor short-term prognosis.

   1. In general, lower GI bleeding carries a better overall prognosis than upper GI bleeding with about half the mortality rate.

   2. Mortality rates for diverticular hemorrhage are higher (11% at 1 year and 20% at 4 years) although the cause of death is rarely related to the GI hemorrhage.

Although diverticular hemorrhage seldom causes death, it is a marker for a relatively poor, short-term prognosis.

EVIDENCE-BASED DIAGNOSIS

1. History and physical exam

   1. The first step in making the diagnosis of any GI bleed is to determine whether the source of the bleeding is the upper or lower tract. Other than frank hematemesis, only a few features are strongly predictive in localizing the site of bleeding to the upper or lower tract. These are outlined in Table 19-2.

      1. Patients who are volume depleted, orthostatic, or hypotensive are about twice as likely to have an upper GI bleed than a lower GI bleed.

      2. Because urea is produced as blood is processed throughout the GI tract, a BUN/creatinine ratio > 30 suggests an upper GI source (sensitivity, 39%; specificity, 94%; LR+, 7.5; LR−, 0.64)

      3. Although hematochezia generally suggests a lower GI source of bleeding, 10–15% of patients with hematochezia have an upper GI source. These patients are more likely to be older and to have duodenal ulcers.

   10–15% of patients with hematochezia have an upper GI source of bleeding.

   2. Beyond differentiating between upper and lower sources of GI bleeding, certain historical features may point to a specific diagnosis (Table 19-3).

      1. These features should be ...