What is the appropriate next step in management for a 50-year-old woman with occult blood in the stool, normal bowel sounds, no abdominal tenderness, and sigmoid diverticula found on imaging?

Management of Occult Blood in Stool with Sigmoid Diverticula

The appropriate next step is colonoscopy to identify the source of occult bleeding, as any positive stool test for blood requires follow-up with colonoscopy regardless of incidental findings like diverticula. 1

Why Colonoscopy is Essential

• Colonoscopy has a diagnostic accuracy of 72-86% in patients with lower gastrointestinal bleeding and allows direct visualization of the entire colon 1, 2
• The presence of sigmoid diverticula on imaging does NOT confirm them as the bleeding source—diverticula are extremely common (present in one-third of people over age 50) and are often incidental findings 3
• Multiple potential bleeding sources must be excluded, as dual pathology (lesions in both upper and lower GI tracts) occurs in 10-15% of patients with occult bleeding 2, 4

Critical Diagnostic Algorithm

Step 1: Colonoscopy First

• Colonoscopy is the preferred initial diagnostic procedure as it allows both visualization and therapeutic intervention if needed 2
• Look for colorectal cancer, large polyps (>2cm), angiodysplasia, and active diverticular bleeding 2
• At age 50, this patient requires colonoscopy regardless due to higher pretest probability of colon cancer 5

Step 2: Upper Endoscopy (EGD) Must Follow

• Even if colonoscopy identifies a potential bleeding source, upper endoscopy should still be performed because dual pathology is common 2, 4
• Obtain small bowel biopsies during EGD to rule out celiac disease, present in 2-3% of patients with iron deficiency anemia 2, 4
• Test for H. pylori, as treatment improves hemoglobin levels when present 2

Step 3: If Both Are Negative

• Capsule endoscopy is recommended as the next step for evaluation of obscure bleeding, as angiectasia accounts for up to 80% of obscure bleeding cases 5, 1
• CT enterography may be appropriate if contraindications to capsule endoscopy exist 1

Key Clinical Pitfalls to Avoid

• Never assume diverticula are the bleeding source without endoscopic confirmation—while diverticular disease causes 10-30% of lower GI bleeds, 90% of diverticula are in the left colon but bleeding originates from the right colon >50% of the time 3, 6
• Do not stop investigation at finding diverticula—the patient needs full evaluation to exclude malignancy and other sources 4
• Avoid accepting minor findings as the sole cause without completing both upper and lower GI evaluation 2
• In patients younger than 50 years, small bowel tumors are the most common cause of obscure bleeding, making aggressive investigation particularly important 1, 2

Understanding Diverticular Bleeding

• Diverticular hemorrhage ceases spontaneously in approximately 90% of cases 3, 6
• Bleeding from diverticula is due to rupture of the vasa recti and typically occurs without associated inflammation or diverticulitis 3, 6
• The intensity varies from massive to occult, and hypertension, anticoagulation, diabetes, and ischemic heart disease are associated risk factors 3