Lower Gastrointestinal (GI) Bleeding

Diagnosis and management of acute lower gastrointestinal bleeding: guidelines from the British Society of Gastroenterology. Published: Jan 2019

Article Last Updated:25/11/2025

Changes made:

Background information added accordingly
Re-structuring and optimisation made to the assessment and management sections

Date: 25/11/25

Background Information

Definition

Upper vs lower GI bleed is an anatomical definition:

Upper GI bleed: bleeding that originates from a source proximal to the ligament of Treitz (duodenal-jejunal ligament)
Lower GI bleed: source distal to the ligament of Treitz

Aetiology

Upper and lower GI bleeding causes (adults mainly): ^[Ref1]^[Ref2]^[Ref3]

	Upper GI bleeding	Lower GI bleeding
Important causes	Peptic ulcer disease – most common cause Oesophagitis / gastritis / duodenitis (erosive disease) Oesophageal / gastric varices Mallory-Weiss tears (mucosal lacerations at the GOJ, typically after episodes of forceful retching or vomiting) (often in the context of alcohol use) Upper GI malignancy	Diverticular bleeding – most common cause Haemorrhoids / anal fissure Colorectal cancer / polyps Colitis Ulcerative colitis > Crohn’s disease Ischaemic colitis Infectious colitis (e.g. Campylobacter)
Rarer causes	Dieulafoy’s lesion (an abnormally large submucosal artery that fails to taper normally and erodes through the gastric mucosa) (it can cause sudden, severe bleeding without preceding symptoms) Gastric antral vascular ectasia (GAVE) (dilated blood vessels in the gastric antrum, arranged in longitudinal red stripes, that give a watermelon appearance) Aorto-enteric fistula (rare but can cause catastrophic bleeding) (suspect in those after aortic aneurysm repair presenting with upper GI bleed)	Rectal ulcer Radiation proctitis Heyde syndrome (triad of aortic stenosis + acquired vWF deficiency + GI bleeding from angiodysplasia)
Shared causes	Antiplatelet / anticoagulant use NSAIDs use Coagulopathies Vascular ectasia (angiodysplasia)

Be aware of some causes that may mimic GI bleeding: ^[Ref]

Iron supplements cause stools to appear like melena
Certain food (e.g. beet root) causes stool to turn red

Some paediatric-specific causes of GI bleeding:

Necrotising enterocolitis	In premature neonates Distended abdomen Feeding intolerance Unwell neonate
Meckel’s diverticulum	In <2 y/o Painless lower GI bleed (large volume) Often requires transfusion
Intussusception	In 6-18 m/o Triad of colicky abdominal pain + palpable sausage-shaped mass + red currant jelly stools (late sign)
Inflammatory bowel disease (ulcerative colitis > Crohn’s disease)	In adolescents

Clinical Features

Presentation of upper vs lower GI bleeding: ^[Ref1]^[Ref2]

Upper GI bleeding	Lower GI bleeding
Common presentation: Haematemesis (vomiting of bright red blood / coffee-ground vomit) Melena (black, tarry, foul-smelling stools – due to digested blood) Rarely, severe upper GI bleeding can cause haematochezia	Presents as haematochezia (passage of fresh blood per rectum) Colonic bleeding Blood mixed with stool Blood is more dark red Rectal bleeding Streaks of blood coating the outside of the stool / blood on toilet paper / drips into the bowel after defecation Blood is more bright red

Upper GI bleeding

Lower GI bleeding

Common presentation:

Haematemesis (vomiting of bright red blood / coffee-ground vomit)
Melena (black, tarry, foul-smelling stools – due to digested blood)

Rarely, severe upper GI bleeding can cause haematochezia

Presents as haematochezia (passage of fresh blood per rectum)

Colonic bleeding
- Blood mixed with stool
- Blood is more dark red
Rectal bleeding
- Streaks of blood coating the outside of the stool / blood on toilet paper / drips into the bowel after defecation
- Blood is more bright red

Non-specific features of bleeding:

Tachycardia
Orthostatic hypotension
Pre-syncope

Assessment

Risk Assessment

BSG recommends using the Oakland score, key components:

Age and sex
Heart rate and systolic BP
Haemoglobin
Any previous lower GI bleeding?
Findings on digital rectal examination?

Do not mix up the scoring systems for GI bleeds:

Upper GI bleed: Glasgow-Blatchford score (pre-endoscopy) and Rockall score (post-endoscopy)
Lower GI bleed: Oakland score

Work-Up

A standard work-up for acute GI bleed would include:

CBC, U&E, LFT
Coagulation tests – PT/INR, APTT
Blood type and crossmatch

Main non-specific biochemical findings in GI bleed:

↓ Haemoglobin (but may be normal initially in acute bleeding)
- Acute bleeding gives a normocytic normochromic anaemia
- Chronic bleeding gives a microcytic hypochromic anaemia (iron deficiency)
↑ Urea with normal creatinine
- Mechanism (“protein meal”): digested blood → ↑ protein absorption → ↑ hepatic urea production → disproportionate rise in urea
- This classic pattern is only seen in upper GI bleeding, as blood is usually NOT digested in lower GI bleeding (so there is no increased protein absorption)

Management

If self-terminating bleed (Oakland score ≤8), with no other indications for admission → discharge for urgent outpatient investigation

Initial Management

A-E approach:

Gain IV access and start IV fluid resuscitation
Transfuse and reverse anticoagulation accordingly (see below)

Transfusion Thresholds

Various transfusion thresholds:

Component	Cut-off
Whole blood	Haemoglobin <70 g/L
Platelet	Platelet count <50 x 10⁹ /L + actively bleeding
Fresh frozen plasma	PT (or INR) or APTT >1.5x normal
Cryoprecipitate	Fibrinogen level <1.5 g/L despite fresh frozen plasma
Recombinant factor VIIa	Only considered if all other methods have failed

Anticoagulation Reversal

Anticoagulant	Reversal agent
Heparin	Protamine sulfate (fully effective for UFH, but only partial reversal for LMWH)
Warfarin	Prothrombin complex concentrate (only consider fresh frozen plasma as 2nd line) + IV vitamin K
Dabigatran	Idarucizumab
Apixaban and rivaroxaban	Andexanet alfa

There is no reversal agent for edoxaban (which is also a DOAC).

There are no reversal agents for antiplatelets (e.g. aspirin, clopidogrel). If patients take antiplatelet → withhold them.

Definitive Management

After initial resuscitation:

Haemodynamically unstable → CT angiography
- If bleeding source identified → catheter angiography + embolisation
- If no bleeding source can be identified → consider upper endoscopy to exclude upper GI bleeding