🩺 Lower GI Bleeding

Lower Gastrointestinal Bleeding (LGIB) refers to bleeding originating distal to the ligament of Treitz, typically from the colon or rectum. While often less acutely life-threatening than UGIB, it is a major cause of hospital admission among older adults. Etiologies vary widely by age, from IBD in younger patients to diverticular disease and malignancy in the elderly. Management involves stabilizing the patient, quantifying the risk of severe bleeding, and using endoscopic or radiological interventions to identify and stop the source.

Differentiate between bright red, fresh blood and darker, altered blood. Assess for associated 'B-symptoms' like weight loss and night sweats, or changes in bowel habit (tenesmus, frequency, consistency). Ask about pain: painless bleeding is common in diverticulosis or angiodysplasia; painful bleeding suggests fissures, ischaemic colitis, or IBD flares. Review medication history for anticoagulants, antiplatelets, and NSAIDs. Travel history and dietary history may be relevant if infective colitis is suspected.

Focus on haemodynamic status and signs of anaemia (conjunctival pallor). Abdominal examination may reveal masses or tenderness (suggesting IBD or diverticulitis). A thorough digital rectal examination (DRE) is essential to look for haemorrhoids, fissures, rectal masses, and the presence of blood or melaena. If required, proctoscopy can be performed at the bedside to visualise the anal canal. Assessment of the skin for extra-intestinal manifestations of IBD (e.g., erythema nodosum) may be relevant.

Diverticular Haemorrhage, Colorectal Carcinoma, Haemorrhoids, Inflammatory Bowel Disease (UC/Crohn’s), Ischaemic Colitis, Angiodysplasia, Anal Fissure, Infective Colitis.

Orthostatic hypotension, persistent bleeding, weight loss, iron deficiency anaemia, change in bowel habit, and tenesmus (a feeling of incomplete evacuation).

Bloods should include FBC (haemoglobin), U&Es, Clotting profile, and Group and Save. The Oakland Score is used to determine if a patient with acute LGIB can be safely discharged for outpatient investigation. Colonoscopy is the gold standard for diagnosis, but if the patient is bleeding too briskly, a CT Angiogram is better for localising the source. For stable patients, a FIT (Faecal Immunochemical Test) is used in primary care to triage suspected colorectal cancer. Flexible sigmoidoscopy may be sufficient for distal pathology.

In many cases, bright red rectal bleeding is due to benign anorectal pathology (haemorrhoids/fissures), but this must never be assumed in patients over 40 without excluding malignancy. Diverticular bleeding is typically painless and voluminous, often stopping spontaneously. A 'maroon' or 'plum-coloured' stool suggests a right-sided colonic bleed or a very brisk upper GI bleed (hematochezia). Always ask about the relationship of blood to the stool (mixed in suggests proximal; on the toilet paper suggests distal).

Students must understand the NICE Suspected Cancer pathway (NG12): patients >40 with unexplained weight loss and abdominal pain, or >50 with unexplained rectal bleeding, require an urgent 2-week wait referral. Be aware of the difference in management between an unstable patient (CT Angio/Interventional Radiology) and a stable patient (Colonoscopy). Recognise that a very rapid Upper GI bleed can present as bright red blood per rectum.