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← Haematology and transfusion indexChapter sections
Purpose and principlesIndications, selection and cautionsAssessment before treatmentTreatment approachRegimens, contraindications and interactionsComplications, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Massive haemorrhage and major transfusion protocol

Haematology and transfusion · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Exsanguinating patient

Major haemorrhage is a time-critical failure of circulation and haemostasis; anatomical source control, blood access and warming proceed in parallel rather than sequentially.

Action: Call the local major-haemorrhage activation number, state location, patient identifiers and clinical context and summon surgical, obstetric, endoscopic, interventional-radiology, anaesthetic and critical-care help as appropriate. Apply direct or mechanical haemorrhage control, obtain large-bore or rapid access, send group and screen, FBC, PT, APTT, fibrinogen, blood gas, calcium, lactate and renal tests and begin protocol blood without waiting for results. Warm patient and fluids, give early tranexamic acid when indicated, monitor ionised calcium and move to result-guided platelets, plasma and fibrinogen as soon as possible.

Purpose and principles

Activate coordinated haemorrhage control early, deliver safe empirical component support, prevent lethal physiological deterioration and transition rapidly to targeted haemostasis.

Major haemorrhage is bleeding severe enough to threaten life and require coordinated clinical and laboratory response. Definitions based on total units are retrospective; activation should use haemodynamic compromise, ongoing rate, injury pattern, site and failure to respond. The immediate goals are to stop bleeding, restore enough circulating oxygen delivery for perfusion and prevent acquired coagulopathy. A senior leader assigns haemorrhage control, airway, access, monitoring, sampling, component checking, documentation and communication roles.

Source control is the definitive treatment. Use direct pressure, tourniquet, pelvic binder, uterotonic and obstetric manoeuvres, endoscopy, surgery, interventional radiology or damage-control technique according to cause. Avoid spending the patient's remaining clot on repeated diagnostic delays. In trauma, take unstable patients with suspected internal haemorrhage to the fastest definitive pathway; permissive hypotension and restricted crystalloid may reduce clot disruption until control, except when traumatic brain injury requires cerebral perfusion. Individualise for pregnancy, older people and chronic hypertension.

Practice

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Haematology and transfusionOriginal SBA

First priority in major haemorrhage

A postoperative patient suddenly becomes hypotensive with rapidly filling abdominal drains. What is the most appropriate immediate management?

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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • British Society for Haematology major haemorrhage guidelineCurrent UK multidisciplinary activation, empirical support, monitoring and targeted-haemostasis framework; reviewed in 2025.
  • NICE NG39 major trauma recommendationsUK trauma haemorrhage control, early tranexamic acid, restrictive volume and adult 1:1 plasma-to-red-cell guidance.
  • NICE NG24 blood componentsUK platelet, plasma and cryoprecipitate decision points outside the empirical phase of major haemorrhage.
  • Resuscitation Council UK 2025 special circumstances guidelineCurrent UK resuscitation principles for traumatic and hypovolaemic cardiac arrest and reversible causes.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom

Activate the local protocol and contact the transfusion laboratory directly. Provide unique identifiers, sex and pregnancy potential, location, cause, urgency and known antibodies or special requirements. Take a pretransfusion group-and-screen sample without delaying blood. Use locally designated emergency group O red cells; D-negative is prioritised for children and females with pregnancy potential, while conservation policy may permit D-positive blood for other adults. Switch to compatible group-specific components when the laboratory confirms a secure group.

Empirical packs prevent isolated red-cell resuscitation while results lag. NICE recommends a 1:1 plasma-to-red-cell ratio for adults with active major trauma bleeding, moving to laboratory-guided ratios at the earliest opportunity. Other settings use local BSH-informed pack composition because obstetric, gastrointestinal, cardiac and surgical haemorrhage differ biologically. Platelets are incorporated or requested according to pack stage and count trajectory. Do not administer components automatically after source control or because a pack has arrived.

Send full blood count, PT, APTT, fibrinogen, blood gas with lactate and ionised calcium, electrolytes and renal profile at activation and repeatedly. Results are time-stamped snapshots during rapid change. Viscoelastic testing can shorten targeted decision-making when the institution has validated equipment, trained staff, quality control and a treatment algorithm. Use it to complement clinical source control and conventional tests. Maintain platelets above 50 × 10⁹/L in ongoing major bleeding and higher for traumatic brain or other critical-site bleeding under the specialist protocol.

Fibrinogen is frequently the earliest coagulation substrate to become critically low. In general major bleeding, cryoprecipitate is considered when fibrinogen is below 1.5 g/L; pregnancy begins at a higher concentration and obstetric protocols commonly target at least 2 g/L during major postpartum haemorrhage. Give cryoprecipitate or the locally commissioned fibrinogen product promptly and recheck. Use FFP for multiple-factor deficiency and abnormal coagulation in active bleeding, generally in weight-based effective doses, not as volume expansion.

Physiology determines whether transfused factors work. Warm the patient, blood and environment; minimise exposure and wet clothing. Correct shock and acidosis primarily through haemorrhage control and perfusion rather than bicarbonate. Citrate chelates calcium during rapid transfusion; monitor ionised calcium on serial blood gases and replace calcium under protocol before severe hypocalcaemia impairs myocardium and clot formation. Check potassium because stored red cells, tissue injury and acidosis can produce hyperkalaemia, while resuscitation can also drive later hypokalaemia.

Tranexamic acid reduces fibrinolytic bleeding when given early in appropriate settings. For major trauma, NICE directs treatment as soon as possible and not beyond three hours after injury unless laboratory evidence of hyperfibrinolysis exists. A widely used adult trauma regimen is 1 g intravenously over 10 minutes followed by 1 g over eight hours. Obstetric and surgical regimens differ, so use the corresponding protocol and adjust or avoid repeated exposure in severe renal impairment because the drug is renally eliminated. Never inject tranexamic acid intrathecally.

Anticoagulant reversal runs in parallel. Identify warfarin, factor Xa or thrombin inhibitor, heparin and antiplatelet exposure and last dose. Use four-factor PCC plus intravenous vitamin K for warfarin major bleeding, protamine for unfractionated heparin and the relevant specific antidote or PCC-based DOAC algorithm according to availability, renal function and timing. FFP is not first-line warfarin reversal. Consult haematology for complex thrombosis risk, mechanical valves, pregnancy or uncertain exposure.

De-escalation is an active safety step. Once bleeding is controlled, tell the laboratory, return unused components under approved temperature and traceability conditions and stop empirical packs. Reassess for dilutional overload, pulmonary oedema, hyperkalaemia, hypocalcaemia, hypothermia and thrombosis. Document total components, reactions and wastage; ensure postoperative or critical-care teams know outstanding tests and the haemoglobin, platelet, fibrinogen, temperature, calcium and anticoagulation plan.

Key points

  • First-line management is immediate major-haemorrhage activation plus anatomical bleeding control; transfusion is support, not source control.
  • Activate on physiology, bleeding rate, mechanism and poor response rather than waiting for an arbitrary unit count or one risk score.
  • Obtain correctly labelled pretransfusion samples before blood if this does not delay resuscitation and tell the laboratory about pregnancy potential, antibodies and special requirements.
  • Use approved emergency group O red cells until the laboratory authorises group-specific blood, then switch promptly to preserve O D-negative stock.
  • For adult major trauma with active bleeding, NICE recommends plasma and red cells in a 1:1 ratio initially, changing to laboratory-guided ratios as soon as possible.
  • Do not extrapolate a trauma 1:1 ratio automatically to every gastrointestinal, surgical or obstetric bleed; follow the context-specific local major-haemorrhage pack.
  • Give tranexamic acid as soon as possible for major trauma with active or suspected active bleeding and do not give it more than three hours after injury unless hyperfibrinolysis is demonstrated.
  • Prevent the lethal cycle of hypothermia, acidosis and coagulopathy with active warming, rapid source control and appropriate blood rather than excessive cold crystalloid.
  • Monitor ionised calcium frequently because citrate in blood products causes hypocalcaemia, impaired contraction and worsening coagulation; replace under the local protocol.
  • Target platelets, fibrinogen and plasma using frequent laboratory or validated viscoelastic results; general and obstetric fibrinogen targets differ.
  • Reverse anticoagulants rapidly with the specific or PCC-based pathway; warfarin-associated major bleeding needs four-factor PCC plus intravenous vitamin K, not FFP first-line.
  • Nominate a team leader and transfusion coordinator, count components and communicate both escalation and stand-down to the laboratory.

Indications, selection and cautions

Physiological major haemorrhage

Shock, altered mentation, rising lactate and continuing blood loss justify activation before a predefined unit count is reached.

Occult bleeding

Pelvic, retroperitoneal, thoracic, gastrointestinal or obstetric loss may present as unexplained shock with little external blood.

Developing coagulopathy

Diffuse ooze, falling fibrinogen and platelets, prolonged tests, hypothermia and acidosis show haemostasis is failing.

Citrate toxicity

Hypotension, poor contractility, QT prolongation or low blood-gas ionised calcium during rapid components suggests urgent calcium replacement.

Anticoagulant contribution

Medicine history, renal function and coagulation pattern identify a reversible anticoagulant effect requiring a specific emergency pathway.

Bleeding controlled

Stable physiology, definitive haemostasis and improving results trigger laboratory stand-down and targeted rather than empirical support.

Red flags requiring action

  • Persistent hypotension, tachycardia, altered consciousness, mottling, rising lactate or ongoing visible bleeding despite initial resuscitation indicates uncontrolled haemorrhagic shock.
  • A normal early haemoglobin does not exclude catastrophic acute blood loss because red cells and plasma are initially lost together.
  • Falling fibrinogen, prolonged clotting, thrombocytopenia, hypothermia, acidosis and low ionised calcium predict haemostatic failure and worsening mortality.
  • Pelvic, retroperitoneal, gastrointestinal, obstetric or postoperative bleeding can be concealed; unexplained shock requires immediate source imaging or intervention without repeated ward observation.
  • Failure to communicate cessation of bleeding to the transfusion laboratory wastes scarce components and increases incompatible handover and overload risk.

Assessment before treatment

  1. 01
    First-line: group and antibody screenFirst stepFirst line
    Why
    Enable rapid transition from emergency group O to group-specific and antigen-appropriate blood.
    Interpretation and limitations
    Take before transfusion when possible without delay; communicate historical antibodies and switch only when the laboratory authorises.
  2. 02
    First-line: FBC, PT, APTT and fibrinogenFirst line
    Why
    Track anaemia, platelet loss, factor deficiency and fibrinogen depletion.
    Interpretation and limitations
    Repeat frequently because initial haemoglobin may be normal and results evolve; use context-specific platelet and fibrinogen targets.
  3. 03
    Blood gas, lactate and ionised calcium
    Why
    Measure shock, acidosis, ventilation and citrate-related hypocalcaemia at the bedside.
    Interpretation and limitations
    Falling lactate and improving base deficit suggest restored perfusion; replace low calcium and investigate persistent acidosis as ongoing blood loss.
  4. 04
    Electrolytes, creatinine and temperature
    Why
    Detect hyperkalaemia, renal injury and hypothermia that impair resuscitation.
    Interpretation and limitations
    Treat dangerous potassium immediately, adjust renally cleared medicines and actively warm below-normal temperature.
  5. 05
    Viscoelastic haemostasis testing
    Why
    Guide rapid targeted component or fibrinogen treatment where locally validated.
    Interpretation and limitations
    Interpret through the institutional algorithm and quality controls; it is not a universal stand-alone gold standard.
  6. 06
    Cause-directed imaging or procedure
    Why
    Locate and control concealed bleeding.
    Interpretation and limitations
    Use only when it advances definitive haemostasis without destabilising transfer; unstable patients may require immediate theatre or interventional control.

Treatment approach

01ActivateMobilise the whole pathwayFirst stepEscalationBleeding and physiology suggest life-threatening or rapidly escalating blood loss.+
  1. 1Call the major-haemorrhage number and summon the appropriate procedural, anaesthetic, critical-care and transfusion teams.
  2. 2State identifiers, location, cause, pregnancy potential, antibodies and urgency; assign a component coordinator and recorder.
  3. 3Apply immediate source control, establish access, send correctly labelled samples and start active warming.
02Empirical resuscitationDeliver protocol blood without avoidable delayActive severe bleeding continues before reliable haemostatic results are available.+
  1. 1Use emergency group O red cells then switch to authorised group-specific blood as soon as possible.
  2. 2For adult active major trauma use initial plasma and red cells 1:1; for other causes use the specific local pack rather than assuming the trauma ratio.
  3. 3Give early tranexamic acid when indicated, monitor calcium and avoid excessive crystalloid and hypothermia.
03Targeted haemostasisReplace the measured deficitLaboratory or validated viscoelastic results become available during ongoing bleeding.+
  1. 1Review bleeding, platelet count, PT, APTT, fibrinogen, temperature, calcium, pH and anticoagulant exposure together.
  2. 2Give platelets, plasma, cryoprecipitate or reversal agent to the relevant threshold and context, with higher critical-site and obstetric targets where required.
  3. 3Repeat tests after intervention and continue source control; do not chase normal values after haemostasis is achieved.
04Anticoagulant-associated bleedingReverse specifically and rapidlyMajor bleeding occurs with warfarin, heparin or a direct oral anticoagulant effect.+
  1. 1Establish medicine, last dose, indication, renal function and relevant coagulation testing without delaying treatment.
  2. 2Use four-factor PCC plus intravenous vitamin K for warfarin, protamine for heparin and the commissioned specific or PCC-based DOAC pathway.
  3. 3Plan when and how thromboprophylaxis or therapeutic anticoagulation will restart after haemostasis, balancing the original thrombotic indication.
05Stand-downStop empirical exposure safelyDefinitiveDefinitive source control and physiological stability have been achieved.+
  1. 1Tell the transfusion laboratory immediately and cancel or return unused components through validated transport and temperature control.
  2. 2Recheck clinical state, FBC, coagulation, fibrinogen, calcium, potassium, temperature and gas exchange and treat residual deficits selectively.
  3. 3Document totals, wastage, reactions and outstanding care and hand over the thrombosis, anaemia and monitoring plan.

Regimens, contraindications and interactions

Antifibrinolytic treatment that stabilises clot during active or suspected active major traumatic bleeding alongside immediate haemorrhage control.

Tranexamic acid in major trauma

Give 1 g intravenously over 10 minutes as soon as possible after injury, followed by 1 g intravenously over 8 hours; start within 3 hours of injury and do not use later unless laboratory evidence of hyperfibrinolysis supports it.

Use the obstetric, surgical or gastrointestinal protocol rather than automatically copying the trauma regimen. Reduce repeated dosing in renal impairment under the product guidance, assess thrombosis and seizure risk and never administer by the intrathecal route; route confusion is frequently fatal.

Replaces citrate-bound calcium to support myocardial contraction, vascular tone and coagulation during rapid component administration.

Calcium chloride during major transfusion

When ionised hypocalcaemia develops during rapid major transfusion, give 10 mL of 10% calcium chloride intravenously, providing about 6.8 mmol calcium, through secure central or large-bore access under the local protocol and repeat according to ionised calcium and ECG response.

Calcium chloride is vesicant and extravasation can cause tissue necrosis; calcium gluconate is safer peripherally but provides less elemental calcium per volume. Use blood-gas monitoring rather than blind repeated dosing and avoid simultaneous administration through the same line as bicarbonate or phosphate-containing solutions.

Complications, monitoring and follow-up

  • Use continuous ECG, oxygen saturation and frequent blood pressure, perfusion, mental-state and bleeding assessment throughout active resuscitation.
  • Repeat blood gas, lactate, ionised calcium, potassium, haemoglobin, platelets, PT, APTT and fibrinogen at intervals matched to bleeding velocity and after major interventions.
  • Maintain an exact running record of red cells, plasma, platelets, cryoprecipitate, medicines, crystalloid, urine output and estimated ongoing blood loss.
  • Monitor core temperature and apply active warming to patient, room, infusions and exposed areas.
  • After control, watch for TACO, TRALI, haemolysis, electrolyte disturbance, renal injury, thrombosis and recurrent concealed bleeding.
  • Review anticoagulation and thromboprophylaxis daily after haemostasis because reversal and major bleeding create competing recurrent bleeding and thrombosis risks.

Special situations

Activation is prospective

A definition based on ten units identifies yesterday's survivor; physiology and bleeding trajectory identify the patient who needs the protocol now.

Haemoglobin equilibrates late

Acute whole-blood loss can leave concentration initially unchanged, so a reassuring first result must not overrule shock.

Ratios are a bridge

Empirical packs cover laboratory delay; result-guided haemostasis should replace fixed-ratio exposure as soon as reliable data arrive.

Trauma is not every bleed

NICE's 1:1 plasma-to-red-cell recommendation is specific to adult major trauma and should not erase obstetric or surgical protocols.

Calcium is part of circulation

Citrate-related hypocalcaemia weakens both myocardium and clot formation and can make otherwise adequate component delivery appear ineffective.

Stand-down saves patients and blood

Prompt cancellation prevents needless exposure, overload, wastage and confusion after the source has been controlled.

Common pitfalls

  1. 01

    Do not wait for haemoglobin to fall before activating a protocol in shock with active bleeding.

  2. 02

    Do not allow component delivery to distract from definitive anatomical source control.

  3. 03

    Do not use the adult trauma 1:1 ratio automatically for every cause of major bleeding.

  4. 04

    Do not continue large volumes of cold crystalloid while coagulopathy and hypothermia worsen.

  5. 05

    Do not overlook ionised calcium, temperature, pH and potassium while counting units.

  6. 06

    Do not give tranexamic acid beyond three hours after trauma without evidence of hyperfibrinolysis.

  7. 07

    Do not use FFP as first-line warfarin reversal when PCC plus vitamin K is indicated.

  8. 08

    Do not delay switching from emergency group O after safe group-specific blood is authorised.

  9. 09

    Do not forget to stand down the laboratory and return unused components correctly.