Blood in Colostomy Bag Not from Stoma: Differential Sources

Blood appearing in a colostomy bag but not originating from the stoma itself suggests distal gastrointestinal bleeding. Potential sources:

• Hemorrhoids: Bright red blood per rectum (BRBPR) with defecation.
• Anal fissure: Sharp pain + bright blood on stool/paper.
• Diverticular bleeding: Painless, often large-volume BRBPR.
• Rectal prolapse: Mucosal protrusion with bleeding.
• Colitis: Ulcerative colitis, Crohn's, infectious, ischemic – diarrhea + blood.
• Neoplasia: Polyps, adenocarcinoma – occult or overt bleeding.

Urgent evaluation: Colonoscopy (preferred) or CT colonography + upper endoscopy if obscure. Hemodynamic instability → resuscitation + angiography/embolization. Do not assume stoma-related; the colon proximal to the stoma can bleed.