How should I manage a patient with suspected diverticulitis who presents with melena (black, tarry stool)?

Management of Diverticulitis with Melena

A patient with suspected diverticulitis presenting with melena requires immediate assessment for hemodynamic stability, resuscitation if needed, and urgent upper endoscopy to rule out an upper GI source before attributing the bleeding to diverticular disease. 1

Initial Assessment and Stabilization

Hemodynamic evaluation is the absolute first priority:

• Assess blood pressure, heart rate, and signs of shock immediately upon presentation 1
• Insert a nasogastric tube to protect the airway, decompress the stomach, and help localize the bleeding source 1
• Begin intravenous fluid resuscitation with crystalloids to normalize blood pressure and heart rate before any endoscopic intervention 1

Transfusion thresholds:

• Transfuse packed red blood cells to maintain hemoglobin above 7 g/dL in stable patients 1
• Use a higher threshold of 9 g/dL for patients with massive bleeding, cardiovascular disease, or anticipated delays in therapeutic intervention 1

Diagnostic Approach

Melena indicates upper GI bleeding until proven otherwise:

• In a hemodynamically stable patient, perform esophagogastroduodenoscopy (EGD) first to exclude upper GI sources such as peptic ulcer disease or gastritis 1
• This is critical because even in patients with known diverticular disease, melena is far more commonly from upper GI pathology than from diverticulitis itself 1

If upper endoscopy is negative and lower GI bleeding is suspected:

• Consider sigmoidoscopy or colonoscopy to evaluate for colonic sources 1
• CT angiography may be useful as a noninvasive diagnostic tool, as it can detect bleeding at rates as low as 0.3 mL/min 1
• Contrast-enhanced CT before colonoscopy increases detection rates for vascular lesions (35.7% vs 20.6%) and leads to more successful endoscopic interventions 1

Role of Angiography

For ongoing bleeding not controlled by endoscopy:

• Angiography requires active bleeding rates > 0.5 mL/min to localize the source 1
• Super-selective angiographic embolization achieves immediate hemostasis in 40-100% of diverticular bleeding cases 1
• Rebleeding occurs in approximately 15% of cases after embolization 1

Critical risks of embolization:

• Bowel ischemia occurs in 1-4% of cases following embolization 1
• Requires administration of IV contrast, which poses nephrotoxicity risk 1

Surgical Indications

Surgery becomes necessary when:

• Massive, life-threatening bleeding continues despite resuscitation and endoscopic/angiographic attempts 1
• Hemodynamic instability persists despite aggressive medical management 1
• The patient develops peritonitis or other signs of complicated diverticulitis with perforation 1

Surgical options depend on patient stability:

• In unstable patients or those with feculent peritonitis, subtotal colectomy with ileostomy (Hartmann procedure) is the safest option 1, 2
• In stable patients with localized disease, segmental resection with primary anastomosis may be considered 2

Critical Pitfalls to Avoid

Do not assume the bleeding is from diverticulitis:

• Melena strongly suggests an upper GI source; failure to perform EGD first can lead to missed diagnoses of peptic ulcer disease, gastritis, or esophageal varices 1
• Even in patients with known Crohn's disease or ulcerative colitis, bleeding may be from associated conditions rather than the inflammatory bowel disease itself 1

Do not rush to surgery without attempting less invasive options:

• In stable patients, endoscopic or angiographic interventions should be attempted first 1
• Unnecessary surgery increases morbidity and mortality, particularly in patients with multiple comorbidities 1

Do not overlook immunocompromised status:

• Immunocompromised patients (on steroids, chemotherapy, or post-transplant) have higher rates of complicated diverticulitis and may fail non-operative management 1, 3
• These patients require more aggressive monitoring and earlier consideration of surgical intervention 1, 3