Lower GI Bleeding: Causes and Management

Causes

1. Diverticular disease
   • Most common cause in adults, especially the elderly.
   • Typically painless, sudden, large-volume hematochezia.
2. Vascular lesions
   • Angiodysplasia/arteriovenous malformations, especially in elderly patients.
   • May cause recurrent, painless bleeding.
   • Other causes: ischemic colitis, rectal varices.
3. Inflammatory and infective colitis
   • Ulcerative colitis, Crohn disease.
   • Infectious colitis.
   • Radiation proctitis/colitis.
   • Usually associated with diarrhea, abdominal pain, fever, or mucus.
4. Neoplasms
   • Colorectal carcinoma and polyps.
   • Post-polypectomy bleeding.
5. Anorectal causes
   • Hemorrhoids.
   • Anal fissure, usually painful bleeding streaking stool or toilet paper.
   • Solitary rectal ulcer.
6. Other causes
   • Meckel diverticulum, especially in children and young adults.
   • Small-bowel tumors or ulcers.
   • Trauma, foreign body, or iatrogenic bleeding.

Management

1. Initial assessment and resuscitation

• Assess airway, breathing, circulation.
• Check hemodynamic status: pulse, BP, postural hypotension, urine output, mental status.
• Insert two large-bore IV cannulas.
• Keep patient nil by mouth.
• Send investigations:
  • CBC and serial hemoglobin
  • Blood grouping and cross-match
  • PT/INR, aPTT, platelet count
  • Renal function, electrolytes, liver function tests
• Give IV crystalloids and transfuse packed red cells if there is significant blood loss or symptomatic anemia.
• Correct thrombocytopenia/coagulopathy and review anticoagulant or antiplatelet drugs.
• In severe hematochezia with instability, exclude an upper GI source with upper endoscopy.

2. Localize the source

• History and examination, including digital rectal examination and proctoscopy where appropriate.
• Colonoscopy after stabilization and adequate bowel preparation is the principal diagnostic test and can also treat the lesion.
• CT angiography (CTA) is preferred in ongoing hemodynamically significant bleeding because it can rapidly localize active extravasation.
• If CTA is positive, proceed urgently to catheter angiography and embolization.
• Tagged red-cell scan or capsule/deep enteroscopy may be considered in selected intermittent or obscure bleeding.

3. Definitive treatment according to cause

• Endoscopic hemostasis: injection therapy, thermal coagulation, clips, or band ligation, according to lesion.
  • Diverticular bleed: clipping, coagulation, or endoscopic band ligation.
  • Angiodysplasia: argon plasma coagulation.
  • Post-polypectomy bleed: clip, injection, or coagulation.
• Colitis: treat the cause, such as antibiotics for infection, steroids/other therapy for IBD, and supportive management for ischemic colitis.
• Hemorrhoids/fissure: conservative treatment, fiber, fluids, stool softener, sitz baths, and definitive anorectal therapy if persistent.
• Cancer/polyp: endoscopic removal or oncologic surgical treatment as indicated.
• Meckel diverticulum: surgical resection.

4. Radiological and surgical treatment

• Transcatheter arterial embolization is indicated for persistent active bleeding with a positive CTA or when endoscopic control is unsuccessful.
• Surgery is reserved for uncontrolled/recurrent massive bleeding despite endoscopic and radiological treatment:
  • Segmental colectomy if the bleeding site is localized.
  • Subtotal colectomy may be needed if bleeding is life-threatening and the site cannot be localized.

5. Prevention of recurrence

• Avoid non-aspirin NSAIDs, especially after diverticular or angiodysplasia-related bleeding.
• Review need for anticoagulants and antiplatelet therapy.
• Treat the underlying lesion and arrange follow-up colonoscopy where indicated.