Synopsis
Stabilise lower gastrointestinal bleeding, distinguish minor self-limited bleeding from major or unstable haemorrhage, and sequence CT angiography, colonoscopy, embolisation and follow-up without assuming every fresh bleed is anorectal.
- Classify unstable versus stable first; a shock index above one is a useful BSG warning, but beta-blockade, pacing and older age can conceal tachycardia.
- Describe bright red, dark red or maroon blood, clots, mixing with stool, dripping, pain and melaena, but colour alone does not reliably locate a brisk bleed.
- In unstable ongoing bleeding, CT angiography is the fastest widely available test to localise active haemorrhage and direct interventional radiology or surgery.
Key red flags
Ongoing large-volume blood with shock index above one, syncope, hypotension, cool peripheries, oliguria or raised lactate indicates major active bleeding and supports immediate resuscitation and CT angiography.
Investigation priorities
Identify unstable bleeding and measure response to resuscitation before definitive localisation.
Management branches
Haematochezia continues with shock or a shock index above one.
- Begin ABCDE, obtain large-bore access, crossmatch, monitor urine output and activate local major-haemorrhage support according to physiology.
- Call gastroenterology, colorectal surgery and interventional radiology early and arrange CT angiography without allowing transport to interrupt resuscitation.
The patient is haemodynamically stable after initial assessment.
Key medicines
Agent-specific anticoagulant reversalFor life-threatening or uncontrolled bleeding, use the current local and BNF reversal regimen matched to warfarin, dabigatran, factor Xa inhibitor or heparin exposure.
Intravenous crystalloid and blood componentsGive warmed crystalloid in limited reassessed boluses and blood components through the local major-haemorrhage or restrictive transfusion strategy according to active physiology.