Level 2 of 6Must-remember

Lower gastrointestinal bleeding

Assess, manage and stay safe — enough on its own

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The card — assess, manage, caution

Assessment— look, ask, measure

Apply the upstream rule before anything else: fresh red blood per rectum *accompanied by shock* is a massive upper GI bleed until proved otherwise, whereas the passage of dark blood and clots *without* shock is most often genuine lower GI bleeding.
Other features pointing upstream: haematemesis, known peptic ulcer or varices, and a raised urea with a normal creatinine — and treat melaena (black, tarry, offensively smelling stool) as an upper GI bleed until proved otherwise, since it can arise from any lesion proximal to the right colon and only rarely from the right colon itself.
Ask: painless or painful? Painless, brisk, large-volume bleeding in an older adult is diverticular disease or angiodysplasia; painful bleeding is ischaemic colitis, an inflammatory or infective colitis, or an anal fissure.
Ask: is the blood on the stool, in the stool, or instead of stool? Blood on the paper or streaking a formed stool is anorectal; blood mixed through loose stool with mucus, urgency and tenesmus is colitic; blood and clots with little faeces suggests a brisk proximal colonic source.
Ask: what has changed over recent months? Weight loss, altered bowel habit, tenesmus and anaemia point to malignancy — weight loss, rectal bleeding or anaemia with constipation mandates colonoscopy to exclude colorectal cancer or stricture.
Ask: how much? Inspect the stool, pad or nappy yourself, because patients over-estimate volume.
Take the drug history: NSAIDs, aspirin, warfarin, direct oral anticoagulants and P2Y12 inhibitors with the time of the last dose; plus previous episodes, known diverticular or inflammatory bowel disease, recent antibiotics, travel or sick contacts, pelvic radiotherapy and any recent polypectomy (delayed haemorrhage occurs within 2 weeks).
Measure the markers of significant loss: pallor, cold peripheries, systolic blood pressure below 100 mmHg and pulse above 100 beats/min, with oliguria, agitation, sweating and syncope — and remember hypotension may be a late finding in a healthy younger adult, in whom orthostatic change and tachycardia precede it, sometimes by litres.
Calculate the shock index (heart rate divided by systolic blood pressure): a value greater than 1 identifies haemodynamic instability and selects the patient for urgent CT angiography rather than colonoscopy as the first investigation.
Decide whether the abdomen is surgical: involuntary guarding, rigidity, rebound, absent bowel sounds, or distension with systemic toxicity converts a medical bleed into a surgical emergency — perforated diverticular disease, transmural ischaemia or toxic dilatation; peritoneal findings may also occur with *C. difficile* or Shiga toxin-producing *Escherichia coli*.
Do a digital rectal examination in every patient to document stool colour on the glove (fresh red, maroon, black and tarry, or brown), detect a rectal mass and assess tenderness; diagnose haemorrhoids by inspection, rectal examination and proctoscopy — but in suspected anal fissure rectal examination is often impossible because of pain and sphincter spasm, so rely on history and perianal inspection.
Exclude two impostors and two false alarms: haematuria and vaginal bleeding; beetroot, tomato and red food colouring which redden stool, and iron or bismuth which blacken it but produce a stool neither tarry nor offensive.
Know the danger signs: shock; continuing large-volume fresh blood and clots; peritonism; distension with fever and tachycardia; anticoagulation with a supratherapeutic INR; a haemoglobin that will not rise despite transfusion; a rising lactate with abdominal pain; falling platelets with rising creatinine after bloody diarrhoea.
Score the low-risk patient with the Oakland score (age, sex, previous lower GI bleed admission, rectal examination findings, heart rate, systolic blood pressure and haemoglobin): a total of 8 points or fewer carries roughly 95% probability of a safe outcome without intervention and supports outpatient management, while higher scores warrant admission.
In children the danger signs differ: any rectal bleeding under 1 year, bilious vomiting, a palpable mass, intermittent screaming with pallor, or bradycardia — children maintain blood pressure until late, so hypotension in a bleeding child is a pre-terminal sign, and urate crystals in a neonatal nappy produce a brick-red stain that is not blood.
Send the bloods that decide management: haemoglobin (normal early — after sudden major haemorrhage it stays normal until haemodilution occurs, so a normal value in the first hour excludes nothing), mean cell volume, urea and creatinine, lactate, INR/PT, APTT, fibrinogen, platelets, blood film and LDH.

Management— do this, in order

Target oxygen saturation 94–98% (88–92% in known chronic obstructive pulmonary disease once stable).
Secure two large-bore peripheral cannulae, 16 gauge or larger, in an unstable patient — flow falls with the fourth power of the radius, and two 20-gauge cannulae will not resuscitate an exsanguinating patient.Doctor / Nurse
Adult, haemodynamically unstable: 0.9% sodium chloride or a balanced crystalloid, 500 mL intravenously over less than 15 minutes, then reassess pulse, blood pressure, capillary refill, conscious level and urine output; repeat as required but move to blood early, and avoid indiscriminate crystalloid because dilutional coagulopathy and hypothermia both worsen bleeding.Doctor / Nurse
Child, shocked: 10 mL/kg boluses of 0.9% sodium chloride intravenously, reassessed after each; if still shocked after 20 mL/kg, give packed red cells 10 mL/kg.Doctor / Nurse
Child, bloody diarrhoea, not shocked: oral rehydration solution 50–100 mL/kg over 24 hours, with intravenous fluids in severe dehydration.
Transfuse to physiology, not to a number: haemoglobin below 70 g/L in low-risk patients and below 90 g/L in high-risk patients (elderly, coronary artery disease), transfuse for instability despite crystalloid resuscitation, and remember hypovolaemic patients with a normal haemoglobin may need blood — but monitor transfusion to avoid overload leading to heart failure.Doctor / NurseNot available at your setup — Blood & blood products.
Correct coagulopathy in parallel with volume replacement, not after it: transfuse platelets if the count is below 50 × 10⁹/L with active bleeding or haemodynamic instability, or with platelet dysfunction from chronic aspirin.Doctor / NurseNot available at your setup — Blood & blood products.
Fresh frozen plasma 15 mL/kg if fibrinogen is below 1 g/L, or PT/INR or APTT is more than 1.5 times normal.Doctor / NurseNot available at your setup — Blood & blood products.
Warfarin with active bleeding: four-factor prothrombin complex concentrate plus phytomenadione (vitamin K1) 5–10 mg by slow intravenous injection, rechecking the INR after reversal; where PCC is unavailable give fresh frozen plasma 15 mL/kg; paediatric phytomenadione 250–300 micrograms/kg IV to a maximum of 10 mg.Doctor / NurseNot available at your setup — Blood & blood products. where PCC is unavailable give fresh frozen plasma 15 mL/kg
Direct oral anticoagulant: stop it, record the time of the last dose and check renal function — half-lives with normal renal function are rivaroxaban 5–9 hours, apixaban 8–15 hours, dabigatran 12–14 hours and edoxaban 10–14 hours, so most GI bleeds settle with resuscitation, blood products and cessation of the drug; idarucizumab reverses dabigatran and andexanet alfa the factor Xa inhibitors.DoctorNot available at your setup — Renal function (creatinine/urea).
Heparins: stop, then protamine sulfate 1 mg per 100 units of unfractionated heparin given in the preceding hour (maximum 50 mg, slow IV); reversal of low-molecular-weight heparin is partial only, 1 mg protamine per 1 mg of enoxaparin given within 8 hours.Doctor / Nurse
Neonate bleeding when vitamin K at birth is not documented: phytomenadione 1 mg intramuscularly (or slow IV) immediately, without waiting for the coagulation screen.Doctor / Nurse
Replace the analgesic: stop NSAIDs and aspirin taken purely for analgesia and substitute paracetamol 1 g orally or intravenously every 6 hours (maximum 4 g in 24 hours; 2 g in significant liver disease); paediatric dose 15 mg/kg every 6 hours (maximum 60 mg/kg in 24 hours).
For severe bleeding, follow the localisation pathway: if available, CT angiography should be performed initially to localise the site of blood loss; if the bleeding source is identified, catheter angiography with embolisation should be performed; if no source of bleeding is found, then a colonoscopy should be performed.DoctorNot available at your setup — CT scan.
Colonoscopy is first-line therapy for most identified colonic sources: endoscopic clipping, alone or after injection of dilute adrenaline (epinephrine), is first-line treatment in the UK for diverticular bleeding, and endoscopic thermal ablation is the treatment of choice for angiodysplasia, with resection if bleeding continues.Doctor
Ischaemic colitis: bowel rest, intravenous fluids, optimisation of cardiac output, and withdrawal of vasoconstrictors and precipitating drugs; antibiotics are commonly given though the evidence is weak, serial abdominal examination is the monitoring tool that matters, and progressive peritonism mandates surgery.Doctor / Nurse
*C. difficile* colitis: non-severe — fidaxomicin 200 mg orally twice daily or vancomycin 125 mg orally four times daily for 10 days; severe or fulminant — vancomycin 500 mg orally four times daily plus metronidazole 500 mg intravenously every 8 hours, with vancomycin also by nasoenteric tube and by rectal enema, 500 mg in 100 mL of 0.9% sodium chloride every 6 hours, if there is ileus.Doctor / Nurse
Anorectal disease: for haemorrhoids with minor symptoms, advice about avoiding constipation with suppositories containing a local anaesthetic and a corticosteroid, then rubber band ligation or injection of a sclerosant if more severe; for anal fissure, local anaesthetic gel and stool softeners plus 0.4% glyceryl trinitrate or 2% diltiazem ointment to the anal margin twice daily for 6–8 weeks.

Caution— what harms

Do not attribute a significant bleed to a haemorrhoid merely because a haemorrhoid is visible: individuals with altered bowel habit, and all those presenting over the age of 40 years, should undergo colonoscopy to exclude coexisting colorectal cancer.
Opioid antidiarrhoeal agents should not be used in patients with bloody diarrhoea, high fever, or systemic toxicity, and antidiarrhoeals given for overflow diarrhoea in faecal impaction cause stercoral ulceration and bleeding.
Avoid empirical antibiotics where Shiga toxin-producing *E. coli* is possible, since they may increase the risk of haemolytic-uraemic syndrome — which complicates 6–22% of STEC infections.
Antibiotics are not indicated for diverticular *bleeding* — they belong to diverticulitis, and giving them for a bleed treats nothing.
Never treat melaena as a lower GI bleed: it implies a lesion proximal to the right colon and must be worked up as an upper GI bleed, with early upper GI endoscopy in any patient with haematochezia and shock or a raised urea.
A normal haemoglobin in the first hour excludes nothing, because after sudden major haemorrhage it stays normal until haemodilution occurs.
Avoid indiscriminate crystalloid — dilutional coagulopathy and hypothermia both worsen bleeding — and monitor transfusion to avoid overload leading to heart failure.
Think before stopping antiplatelet therapy: stopping antiplatelets can be dangerous and may produce thrombosis, and in a patient with coronary stents both agents should be restarted within 5–7 days; in life-threatening bleeding stop everything, in stable low-volume bleeding the usual compromise is to continue aspirin and withhold the P2Y12 inhibitor.
Tranexamic acid is contested and should not be given reflexively here: the HALT-IT trial found no benefit in GI bleeding and raised concern about venous thromboembolism.
Colonoscopy has limits in acute disease: in severe diverticulosis it requires expertise and carries a risk of perforation, and sigmoidoscopy and colonoscopy are not performed during an acute attack of diverticulitis.
A negative CT angiogram in a patient who has stopped bleeding is uninformative rather than reassuring — it detects bleeding at rates around 0.3–0.5 mL/min, and the yield of any localising test collapses once bleeding stops.
Nasogastric aspiration is no longer recommended as a screening test: a clear aspirate does not exclude a duodenal ulcer bleeding beyond a closed pylorus.
Do not start intravenous corticosteroids for acute severe colitis before stool studies have excluded infection, and remember dilatation above 7 cm with systemic toxicity is a surgical emergency whatever the cause.
Rebleeding is the trap of the condition: watch for a rising pulse (the earliest and most sensitive sign), falling blood pressure, fresh blood or clots, falling urine output, a haemoglobin that fails to rise despite transfusion, and a patient who becomes restless, cold, clammy or newly confused — a bleed that has stopped is not a bleed that has been treated.

Refer / escalate

Escalate urgently when the patient is shocked or the shock index exceeds 1 (CT angiography first, then embolisation if a source is found and colonoscopy if it is not), when there is peritonism, distension with systemic toxicity or colonic dilatation above 7 cm, when bleeding continues or rebleeds, when the Oakland score is above 8, or in a child with rectal bleeding under 1 year, bilious vomiting, a palpable mass, intermittent screaming with pallor or bradycardia — and refer everyone over 40 years, or with altered bowel habit, weight loss or anaemia, for colonoscopy even when a haemorrhoid is visible.

The card — assess, manage, caution

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