Level 1 of 6Core
Lower gastrointestinal bleeding
The core to-do list — diagnose and manage, at a glance
Diagnose— recognise it
- Apply the upstream rule first: fresh red blood per rectum *plus shock* is a massive upper GI bleed until proved otherwise, whereas dark blood and clots *without* shock is most often genuine lower GI bleeding. Treat melaena as an upper GI bleed until proved otherwise — other upstream pointers are haematemesis, known ulcer or varices, and a raised urea with a normal creatinine.
- Ask: painless or painful? Painless, brisk, large-volume bleeding in an older adult is diverticular disease or angiodysplasia; painful bleeding is ischaemic colitis, inflammatory or infective colitis, or an anal fissure. Blood on the paper or streaking 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. Inspect the stool, pad or nappy yourself — patients over-estimate volume.
- Calculate the shock index (heart rate ÷ systolic blood pressure): above 1 identifies haemodynamic instability and selects urgent CT angiography, not colonoscopy, as the first investigation. Markers of significant loss: pallor, cold peripheries, systolic BP below 100 mmHg, pulse above 100/min, oliguria, syncope — and hypotension may be late in a healthy younger adult.
- 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. Do a digital rectal examination in every patient to document stool colour, detect a rectal mass and assess tenderness — but in suspected anal fissure it is often impossible from pain, so rely on history and perianal inspection.
- Weight loss, rectal bleeding or anaemia with altered bowel habit mandates colonoscopy to exclude colorectal cancer — never attribute a significant bleed to a visible haemorrhoid, and everyone over 40 needs colonoscopy. The Oakland score of 8 or fewer carries roughly 95% probability of a safe outcome and supports outpatient management.
- 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; urate crystals in a neonatal nappy produce a brick-red stain that is not blood.
Manage now— do this, in order
- Target oxygen saturation 94–98% (88–92% in known COPD once stable) and 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.
- Unstable adult: 0.9% sodium chloride or balanced crystalloid 500 mL IV over less than 15 minutes, reassess pulse, BP, capillary refill, conscious level and urine output after each bolus, and move to blood early — avoid indiscriminate crystalloid (dilutional coagulopathy and hypothermia worsen bleeding). Shocked child: 10 mL/kg boluses; still shocked after 20 mL/kg — packed red cells 10 mL/kg. Child with bloody diarrhoea, not shocked: oral rehydration solution 50–100 mL/kg over 24 hours.Doctor / NurseNot available at your setup — Blood & blood products.
- Transfuse to physiology, not to a number: below 70 g/L in low-risk and below 90 g/L in high-risk patients (elderly, coronary artery disease); transfuse for instability despite crystalloid; a normal haemoglobin in the first hour excludes nothing; monitor to avoid overload leading to heart failure. Correct coagulopathy in parallel: platelets below 50 × 10⁹/L with active bleeding, fresh frozen plasma 15 mL/kg if fibrinogen below 1 g/L or PT/INR or APTT over 1.5 times normal.Doctor / NurseNot available at your setup — Blood & blood products, Coagulation (PT/INR).
- Reverse the anticoagulant (see chart): warfarin with active bleeding — four-factor prothrombin complex concentrate plus phytomenadione 5–10 mg slow IV (paediatric 250–300 micrograms/kg, maximum 10 mg), FFP 15 mL/kg where PCC is unavailable; DOAC — stop, record last dose, check renal function (idarucizumab reverses dabigatran, andexanet alfa the Xa inhibitors); heparin — protamine 1 mg per 100 units given in the preceding hour, maximum 50 mg. A neonate bleeding without documented vitamin K at birth: phytomenadione 1 mg IM 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 IV every 6 hours (maximum 4 g/24 h; 2 g in significant liver disease); paediatric 15 mg/kg every 6 hours (maximum 60 mg/kg/24 h). But think before stopping antiplatelet therapy — thrombosis is as lethal as haemorrhage; restart both agents within 5–7 days in a stented patient.
- For severe bleeding follow the localisation pathway: CT angiography first; if a source is identified, catheter angiography with embolisation; if not, colonoscopy. A negative CT angiogram in a patient who has stopped bleeding is uninformative, not reassuring — it detects bleeding at around 0.3–0.5 mL/min.Doctor / NurseNot available at your setup — CT scan.
- Treat the identified source: endoscopic clipping, alone or after dilute adrenaline injection, is first-line for diverticular bleeding (antibiotics are not indicated for diverticular bleeding); endoscopic thermal ablation for angiodysplasia; ischaemic colitis — bowel rest, IV fluids, optimise cardiac output, withdraw vasoconstrictors, serial abdominal examination, surgery for progressive peritonism.Doctor / Nurse
- Never give opioid antidiarrhoeals in bloody diarrhoea, high fever or systemic toxicity, and avoid empirical antibiotics where Shiga toxin-producing *E. coli* is possible — they may increase the risk of haemolytic-uraemic syndrome, which complicates 6–22% of STEC infections. Do not start IV corticosteroids for acute severe colitis before stool studies exclude infection; dilatation above 7 cm with systemic toxicity is a surgical emergency. *C. difficile*: non-severe — fidaxomicin 200 mg orally twice daily or vancomycin 125 mg orally four times daily for 10 days; severe — vancomycin 500 mg orally four times daily plus metronidazole 500 mg IV 8-hourly.
- Watch for rebleeding — the trap of the condition: a rising pulse is the earliest and most sensitive sign, then falling blood pressure, fresh blood or clots, falling urine output, a haemoglobin that fails to rise despite transfusion, and new restlessness or confusion. A bleed that has stopped is not a bleed that has been treated.
| Anticoagulant | Reversal |
|---|---|
| Warfarin, bleeding | 4-factor PCC + phytomenadione 5–10 mg slow IV (child 250–300 µg/kg, max 10 mg); FFP 15 mL/kg if no PCC |
| DOAC | Stop; record last dose; check renal function. Idarucizumab (dabigatran), andexanet alfa (Xa inhibitors) |
| Unfractionated heparin | Protamine 1 mg per 100 units given in the last hour (max 50 mg, slow IV) |
| LMWH (enoxaparin, within 8 h) | Protamine 1 mg per 1 mg — partial reversal only |
| Neonate, no vitamin K given | Phytomenadione 1 mg IM immediately |
Refer / escalate
Escalate urgently when the patient is shocked or the shock index exceeds 1 (CT angiography first, embolisation if a source is found, colonoscopy if not), for peritonism, distension with systemic toxicity or colonic dilatation above 7 cm, continuing or recurrent bleeding, an Oakland score above 8, or a child with rectal bleeding under 1 year, bilious vomiting, a palpable mass, intermittent screaming with pallor or bradycardia — and refer everyone over 40, or with altered bowel habit, weight loss or anaemia, for colonoscopy even when a haemorrhoid is visible.
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