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Lower GI Bleeding - Coggle Diagram
Lower GI Bleeding
Aetiology: Uncommon from small bowel to ileocaecal vave. MOst common cause= 1. Diverticulosis 2. Angiodysplasia 3. Colitis 4. Neoplasia 5. Haemorrhoids and other anorectal disorders 6. Drug related
- Diverticulosis: presence of pouchlike herniations
through the muscular layers of the colon, usually affects sigmoid. Presents with acute, painless, bright red bleeding (from vaso recta-blood vessels going through bowel wall at site of diverticulae prone to injury and bleeding). Usually settles spontaneously, rarely life threatening.
- Angiodysplasia: degenerative vascular malformation of GI tract, usually in caecum and ascending colon. 5% of LGIB but usually never bleed. Bleeding=coagulopathy/platelet dysfunction.
- Colitis:
- Ischaemic olitis (due to sudden, temporary reduction in mesenteric blood flow usually in older atients with cardiovascylar disease which affects watershed areas of colon- splenic flexure and rectosigmoid areas)=abdo pain, haematochezia/bloody diarrhoea.
- Ulcerative colitis: bloody diarrhoea=iron deficinecy anaemia.
- Infectious = may cause colonic bleeding, not clinically relevant.
- Neoplasia: Low grade bleeding = iron deficiency anaemia. massive bleed unusual.
- Anorectal disease: haemorrhoids=bright red bleeding. rare to cause anaemia. anal fissure/fistula-in-ano=intermittent spotting. more common in immunocompromised patients.
- Drug related: oral anticoagulants, aspirin, NSAIDs can aggravate bleeding from existing lesions.
Treatment
- Resuscitation: airway secured, IV access, blod for croccmatc and arterial blood gas done, mnasograstric tube fro upper GI bleeds, best managed in ICU if multiple comorbidities, mclotting factor replacement and vit K for reverse anticoagulation.
- Localisation of bleeding point: colonoscopy, CT scan with mesenteric angiography. Percutaneous angiography for intervention, tagged RBC scanning can be useful.
- Haemostasis: at colonoscopy=coagulation, haemoclip application, injection therapy. If unsuccessful=formal angiography with a view to transcatheter embolization of bleeding vessel. Surgery if too unstable for angiography/unavailable. If still not localized=on table colonoscopy. Segmental colectomy or total colectomy (last resort). Anastomosis on case by case basis.
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Diagnosis
Lab tests: FBC with platelets. Low mean cell volume=chronic blood loss. normal Hb=can still be GI bleed. Clotting factors checked. Specimen taken to crossmatch in acute bleeds.
Radiology: 1. PLain abdo X-ray: useful in IBD 2. US not useful 3. CT scan + mesenteric angiography=find site of bleed in 50-90% and most accurate when bleeding actively at 1ml/minute. 4. Technetium-labeled RBC scanning: nuclear medicine where radiolabelled RBC localise site of bleed from 0.1ml/min. 25% false localization and not widelt available. 5. Selective mesenteric angiography: diagnoistic + therapeutic: 0.5-1ml/min; Vasopresin infusion in bleeding vessel = stops bleed but rebledding happens. Reduces risk of bowel ischaemia. Angioembolisation preferred.
Endoscopy: primary diagnostic and therapeutic modality in LGIB. excludes proximal cause of bleed. sigmoidoscopy in young patient with anorectal bleed. rapid bowel prep for acute LGIB, standard bowel prep for elective.
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Epidemiology: incidence in western world: 20.5-27 per 100000; increases with age; M>W. Acute bleeding usually stops spontaneously. Overall mortality=2-4%, increases with age and comorbidity.
Clinical presentation: acute/chronic/occult (positive faecal occult blood test but no signs/symptoms): Massive LGIB can present with: -passage of large amounts f red or maroon blood per rectum (haematochezia), haemodynamic instability/shock, initial Hb of 8g/dl or less, bleeding that continues for 3 days, significant rebleeding within a week.
