AKT · Gastroenterology/GI bleedinglow yield

Lower GI bleeding

Bleeding distal to the ligament of Treitz (diverticular, angiodysplasia, cancer, IBD, haemorrhoids)

Overview

Bleeding from the colon/rectum/anus — fresh red or dark blood per rectum (haematochezia). Commonest causes: diverticular disease (painless brisk bleeding) and angiodysplasia (often elderly/aortic stenosis/renal disease); also colorectal cancer, IBD, ischaemic colitis, haemorrhoids/fissure. Most settle; resuscitate, exclude an upper GI source if brisk/unstable, then localise (CT angiography/colonoscopy). The priority is excluding cancer in at-risk patients.

Recognise

Fresh/dark blood per rectum (haematochezia); diverticular = painless and brisk; angiodysplasia = recurrent, often elderly with aortic stenosis/CKD (Heyde syndrome)
Mixed-in blood + change in habit + weight loss → cancer/IBD; bright blood on wiping → haemorrhoids/fissure
Massive/brisk upper GI bleed can present as haematochezia with haemodynamic compromise

Red flags

Haemodynamic instability/brisk bleeding → resuscitate; a rapid upper GI bleed can mimic lower (insert NG/upper endoscopy if unstable)
Bleeding with change in habit/weight loss/anaemia → colorectal cancer pathway

Differentials & how to tell them apart

Diverticular bleedpainless, brisk, often self-limiting; elderly

Angiodysplasiarecurrent obscure bleeding/iron deficiency; aortic stenosis (Heyde)/CKD

Colorectal cancer/polypchange in habit, weight loss, anaemia — colonoscopy

Upper GI bleed (brisk)haemodynamic compromise + raised urea — exclude an upper source

Investigations

Resuscitate; FBC, U&Es, clotting, crossmatch. CT ANGIOGRAPHY for active brisk bleeding (localise); COLONOSCOPY when stable (diagnostic + therapeutic). Exclude an upper GI source (raised urea, NG aspirate/OGD) if unstable.

Management

Resuscitate + CT angiography (if brisk)/colonoscopy; treat the cause (exclude cancer)

1Resuscitate. Most lower GI bleeds settle. Use CT angiography to localise active brisk bleeding; colonoscopy when stable.Gate: If the patient is HAEMODYNAMICALLY UNSTABLE, exclude a brisk UPPER GI source first (raised urea, upper endoscopy) — a rapid upper bleed can present as fresh rectal blood; and investigate any bleed with red flags for colorectal cancer
2Cause-directed: colonoscopic therapy (diverticular/angiodysplasia), embolisation, or surgery for uncontrolled bleeding; treat cancer/IBD; aortic valve replacement resolves Heyde-related angiodysplasia.

Resuscitation + transfusion — as for any GI bleed; most lower GI bleeds settle

Endoscopic/radiological/surgical haemostasis — colonoscopic therapy, embolisation (CT angiography), or surgery for ongoing bleeding

Key points

Haematochezia → resuscitate; most settle. Painless brisk = diverticular; recurrent + aortic stenosis = angiodysplasia (Heyde). Exclude an upper source if unstable; exclude cancer if red flags.

Monitor & prognosis

Haemodynamics, Hb, rebleeding.

Most self-limiting; depends on cause.

Source: BSG (lower GI bleeding)