see also: [[Upper GI Bleed]], [[Blood in infant stool]], [[Gastroenteritis#Bloody vs non-bloody diarrhoea DDx table|Bloody vs non-bloody diarrhoea ddx]] See: [Tintinalli - lower gastrointestinal haemorrhage](x-devonthink-item://3AC86672-A078-47D7-98C9-4889428EE94A?page=25), [Dunn - Lower intestinal haemorrhage](x-devonthink-item://14E0398C-1EC5-41CE-8314-DF70822C8773) *haematochezia*: bright red or maroon-colored rectal bleeding. if from upper GI source, indicated brisk upper GI bleeding. note, can get melena from slow bleeding lower GI source **Causes** - angiodysplasia / angioectasia - thin-walled, dilated, ectatic bloood vessels - more common in elderly - usually not very severe - AV malformations - diverticulosis / diverticulitis - can be massive - often painless - haemorrhoids - colitis (eg [[Mesenteric ischaemia]] / ischaemic colitis ), radiation colitis - malignancy (GI carcinoma) - post polypectomy bleeding - upper GI bleed - foreign bodies - colonic varicies - inflammatory (ulcertive colitis/Crohns) - infectious (salmonella, campyloacter) - fissures *in kids:* (see [[Blood in infant stool]]) - meckel diverticulum - anorectal fissure - allergic colitis - polyps - angiodysplasia - peutz jegher syndrome (multiple GI haemangiomata) - [[Henoch-Schonlein Purpura|HSP]] **Risk assessment** - bright red bleeding - haemodynamically unstable - blood loss > 500mL - prior abdo vascular surgeries - use of anticoagulants - lactate >4 - Hb < 10 **management** - CT angio → IR if source found - dx and therapy requires relatively brisk bleeding at least 0.5mL/min - likely colonoscopy and flexi sig if cannot find lower GI active bleed on angiography - General guidelines for initiation of blood transfusion are continued active bleeding and failure to improve perfusion and vital signs after crystalloid infusion or if hemoglobin falls below 7 g/dL. - The threshold for blood transfusion should be lower in the elderly and those with multiple comorbid conditions. - Consider the placement of a nasogastric tube if lower GI bleeding is significant. *Hematochezia unexpectedly originates from upper GI sources approximately 10% to 14% of the time.*