What is the treatment for a patient presenting with constipation and melena?

Treatment for Constipation and Melena

The presence of melena with constipation mandates immediate endoscopic evaluation to identify and treat the bleeding source before addressing constipation, as melena indicates gastrointestinal bleeding that requires urgent diagnosis and hemostasis. 1

Immediate Priority: Address the Melena (GI Bleeding)

Acute Assessment and Stabilization

• Patients with acute bleeding presenting as melena should undergo prompt endoscopic assessment as the first-line diagnostic and therapeutic intervention 1
• Hemodynamically unstable patients require IV fluid resuscitation and red blood cell transfusion to maintain hemoglobin levels 1
• Complete blood count is essential to assess severity of blood loss 1

Diagnostic Approach for Melena

• Upper endoscopy (EGD) is the initial procedure since melena typically indicates bleeding proximal to the ligament of Treitz 2, 3
• If EGD is nondiagnostic, colonoscopy should be performed as melena can originate from lower GI sources, though the diagnostic yield is relatively low (4.8%) 2
• The presence of melena doubles the odds of finding a bleeding source in the proximal small intestine, suggesting antegrade deep enteroscopy if capsule endoscopy is pursued 3
• CT angiography (CTA) can detect bleeding rates as low as 0.3 mL/min and should be considered if endoscopy is nondiagnostic 1
• Angiographic embolization may be necessary when endoscopy fails to control bleeding 1

Therapeutic Interventions for Bleeding

• Endoscopic therapies include injection therapy, mechanical therapy (endoscopic clips), and ablative therapy (argon plasma coagulation) 1
• External beam radiation therapy can effectively manage both acute and chronic gastrointestinal bleeding when other methods fail 1
• Proton pump inhibitors (IV initially, then oral) should be administered to reduce bleeding risk and promote healing 1

Secondary Priority: Managing Constipation

Critical Caveat

Do NOT aggressively treat constipation until the bleeding source is identified and controlled, as stimulant laxatives and increased bowel motility could potentially worsen active bleeding or mask ongoing hemorrhage 1

Once Bleeding is Controlled

Initial Evaluation

• Perform digital rectal examination to assess for impaction, pelvic floor dysfunction, and rectal masses 1
• Colonoscopy is mandatory in this case given the alarm symptom of melena (blood in stools), regardless of age-appropriate screening status 1
• Rule out mechanical obstruction, which can present with both constipation and melena 4
• Discontinue medications that cause constipation if feasible 1

Pharmacological Management

• Start with a stimulant laxative (bisacodyl 10-15 mg daily or senna) combined with a stool softener as first-line therapy 5, 6
• Add osmotic laxatives (polyethylene glycol 17g with 8 oz water twice daily) if stimulant laxatives alone are insufficient 5, 6
• Titrate stimulant laxatives up to three times daily if needed to achieve one non-forced bowel movement every 1-2 days 5, 6
• Consider adding a prokinetic agent (metoclopramide 10-20 mg PO four times daily) for severe or refractory cases 5

Supportive Measures

• Increase fluid intake to support laxative efficacy 5, 6
• Encourage physical activity when clinically appropriate 5, 6
• Increase dietary fiber only if patient has adequate fluid intake and physical activity 6

Common Pitfalls to Avoid

• Never treat constipation aggressively before ruling out mechanical obstruction or ongoing bleeding, as this can lead to perforation or worsened hemorrhage 4
• Do not rely on stool softeners alone without stimulant laxatives, as this approach is ineffective 5, 6
• Do not delay colonoscopy in patients with melena and constipation, as this combination represents an alarm feature requiring structural evaluation 1
• Be aware that CT imaging may reveal multiple pathologies; carefully review all findings rather than focusing only on the most obvious abnormality 4
• Do not assume melena always originates from upper GI sources—colonoscopy has diagnostic value even after nondiagnostic EGD 2