[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anaesthesia and ICU](https://durgical.com/en/anaesthesia/) › [Intraoperative crises](https://durgical.com/en/anaesthesia/areas/crises/) › Massive haemorrhage in theatre

# Massive haemorrhage in theatre

- Crisis

When a patient bleeds heavily during surgery, the team stops the bleeding, replaces blood with balanced blood products and keeps the patient warm.

Updated Nov 13, 2026

## Key points

- Activate the massive transfusion protocol early and give red cells, plasma and platelets in a balanced ratio near 1:1:1.
- Limit crystalloid: it dilutes clotting factors, cools the patient and worsens acidosis.
- Give tranexamic acid early, within three hours of trauma; replace fibrinogen and calcium guided by tests.
- Fight the lethal triad: warm every fluid and the patient, correct acidosis by restoring perfusion, treat coagulopathy.
- Permissive hypotension is for selected trauma until bleeding is controlled; it is contraindicated in traumatic brain and spinal cord injury.

On this page

- The basics Key points
- What it is
- How to recognise it
- Why it happens
- What to do at once
- The lethal triad and its fourth partner, and how each is fought
- Costly mistakes
- Next step
- Memory aid
- Elsewhere in DurgiPedia

- Study Test yourself

- Connections Connections

## What it is

Massive haemorrhage is blood loss fast enough to threaten life: roughly the loss of a whole blood volume within a day, half of it within a few hours, or bleeding that needs rapid, repeated transfusion to keep the circulation going. In theatre it happens in trauma, obstetrics, vascular, liver and cancer surgery, or when a major vessel is injured. The patient falls into a vicious circle known as the lethal triad: hypothermia, acidosis and coagulopathy, each worsening the others; low ionised calcium from the citrate in stored blood makes it worse. Modern management is damage-control resuscitation: surgical control of bleeding as the priority, early activation of the hospital's massive transfusion protocol, blood products given in a balanced ratio close to whole blood (red cells, plasma and platelets around 1:1:1) instead of large volumes of crystalloid, early tranexamic acid, replacement of fibrinogen and calcium, and active warming. Until bleeding is controlled, a lower-than-normal blood pressure (permissive hypotension) may be accepted in selected trauma patients, but not with head or spinal cord injury.

## How to recognise it

- Rapid blood loss in suction canisters, swabs and drapes, or a surgeon reporting uncontrolled bleeding.
- Tachycardia, falling blood pressure and pulse pressure, a shock index (heart rate over systolic pressure) above one.
- Falling end-tidal carbon dioxide and wide swings of the arterial trace with ventilation.
- Cold, pale peripheries, falling urine output and a rising lactate.
- Oozing from wounds and line sites, a sign that coagulopathy has begun.

## Why it happens

- Loss of circulating volume lowers venous return, cardiac output and oxygen delivery, so tissues switch to anaerobic metabolism and lactic acidosis follows.
- Clotting factors and platelets are consumed and diluted by crystalloid and red cells alone.
- Hypothermia from exposure and cold fluids slows the clotting enzymes and platelet function.
- Acidosis further impairs clotting enzymes and heart contraction.
- Citrate in stored blood binds calcium, which is needed for clotting and for heart and vessel tone; stored blood can also raise potassium.

## What to do at once

- Declare major haemorrhage and call for help — saying it aloud mobilises the team, the blood bank and a senior surgeon.
- Ask the surgeon for control: pressure, packing, clamps, damage-control surgery — no transfusion keeps up with uncontrolled bleeding.
- Activate the massive transfusion protocol and name a runner and a communicator — the blood bank prepares packs in a fixed ratio.
- Secure wide-bore venous access and an arterial line — flow depends on cannula size, and beat-to-beat pressure guides resuscitation.
- Give uncrossmatched group O red cells until group-specific blood arrives — delay costs more than the small risk of unmatched blood.
- Transfuse red cells, plasma and platelets in a balanced ratio through a rapid warmer — this replaces what is lost, not only the volume.
- Give tranexamic acid early — it blocks fibrinolysis and saves lives in trauma and postpartum bleeding.
- Replace calcium and fibrinogen guided by tests — citrate lowers calcium and fibrinogen falls first in heavy bleeding.
- Warm the patient and all fluids and correct acidosis — cold and acid stop clotting factors working.
- Send blood tests every half hour or so: blood count, coagulation, fibrinogen, gases, calcium, potassium — results steer the next packs.

## The lethal triad and its fourth partner, and how each is fought

| Problem | Why it matters | What the team does |
| --- | --- | --- |
| Hypothermia | Slows clotting enzymes and platelets | Fluid warmer, forced-air warming, warm theatre, cover the patient |
| Acidosis | Weakens clotting and heart contraction | Restore perfusion with blood, stop the bleeding |
| Coagulopathy | Bleeding becomes generalised | Balanced products, tranexamic acid, fibrinogen replacement |
| Low ionised calcium | Citrate binds calcium; vessels and clotting fail | Measure and replace calcium during transfusion |

## Costly mistakes

- Activating the protocol too late, or waiting for laboratory results before giving plasma and platelets.
- Pouring in large volumes of crystalloid, causing dilution, cooling and tissue oedema.
- Forgetting calcium, so the patient stays hypotensive and coagulopathic despite products.
- Not warming fluids or the patient, allowing hypothermia to undo the transfusion.
- Forgetting to stand down the protocol once bleeding is controlled, wasting scarce blood.

## Next step

- Once bleeding is controlled, stand down the massive transfusion protocol and switch to test-guided, targeted transfusion.
- Keep a senior anaesthetist and surgeon involved; consider interventional radiology or a return to theatre if bleeding restarts.
- Transfer to intensive care for monitoring of coagulation, potassium, calcium, lactate and temperature.
- Watch for transfusion reactions, circulatory overload, transfusion-related lung injury and acute kidney injury in the following hours and days.
- Record every product given with its unit identifiers, inform the patient and family, and debrief the team.

## Memory aid

Cold, acid, clot, and calcium: the lethal triad plus the partner that transfusion itself causes.

## Test yourself

Think of the answer, then tap the question to see it.

## What ratio of blood products is used in damage-control resuscitation for massive haemorrhage?

Red cells, plasma and platelets in a balanced ratio close to 1:1:1, which approximates whole blood, with limited crystalloid.

## What are the three parts of the lethal triad in massive haemorrhage?

Hypothermia, acidosis and coagulopathy, each worsening the others; low ionised calcium from transfused citrate adds a fourth problem.

## Why must calcium be monitored and replaced during massive transfusion?

The citrate used to store blood binds calcium; low ionised calcium impairs clotting, heart contraction and vascular tone.

## In which patients is permissive hypotension contraindicated?

In traumatic brain injury and spinal cord injury, where low blood pressure reduces perfusion of the injured nervous tissue and worsens outcome.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anaesthesia/massive-haemorrhage-in-theatre/)

## Elsewhere in DurgiPedia

- [Blood groups, transfusion and transfusion reactions](https://durgical.com/en/physiology/blood-groups-transfusion-and-transfusion-reactions/)
- [Coagulation tests: PT/INR, aPTT and platelets](https://durgical.com/en/physiology/coagulation-tests-pt-inr-aptt-and-platelets/)
- [Shock physiology](https://durgical.com/en/physiology/shock-physiology/)
- [Blood transfusion: bedside checks, monitoring and reactions](https://durgical.com/en/nursing/blood-transfusion-bedside-checks-monitoring-and-reactions/)
- [Coagulation tests: PT/INR, aPTT, fibrinogen and D-dimer](https://durgical.com/en/clinical-skills/coagulation-tests-pt-inr-aptt-fibrinogen-and-d-dimer/)
- [Shock: the clinical signs and the types](https://durgical.com/en/clinical-exam/shock-the-clinical-signs-and-the-types/)

## Connections

## Related 7

- [Intraoperative hypotension](https://durgical.com/en/anaesthesia/intraoperative-hypotension/)
- [Trauma and emergency surgery](https://durgical.com/en/anaesthesia/trauma-and-emergency-surgery/)
- [Transfusion thresholds in the ICU](https://durgical.com/en/anaesthesia/transfusion-thresholds-in-the-icu/)
- [Shock: a bedside approach by type](https://durgical.com/en/anaesthesia/shock-a-bedside-approach-by-type/)
- [Perioperative hypothermia and shivering](https://durgical.com/en/anaesthesia/perioperative-hypothermia-and-shivering/)
- [Obstetric anaesthesia and caesarean section](https://durgical.com/en/anaesthesia/obstetric-anaesthesia-and-caesarean-section/)
- [Vasopressors and inotropes by receptor and mechanism](https://durgical.com/en/anaesthesia/vasopressors-and-inotropes-by-receptor-and-mechanism/)

## Related conditions 6

- [Hypovolaemic shock](https://durgical.com/en/conditions/hypovolaemic-shock/)
- [Disseminated intravascular coagulation](https://durgical.com/en/conditions/disseminated-intravascular-coagulation/)
- [Transfusion reactions](https://durgical.com/en/conditions/transfusion-reactions/)
- [Postpartum haemorrhage](https://durgical.com/en/conditions/postpartum-haemorrhage/)
- [Major trauma (polytrauma): ATLS primary survey](https://durgical.com/en/conditions/major-trauma-atls-primary-survey/)
- [Hyperkalaemia](https://durgical.com/en/conditions/hyperkalaemia/)

## In Pharmacology 5

- [Tranexamic acid](https://durgical.com/en/pharmacology/tranexamic-acid/)
- [Calcium chloride](https://durgical.com/en/pharmacology/calcium-chloride/)
- [Calcium gluconate](https://durgical.com/en/pharmacology/calcium-gluconate/)
- [Vasopressors and inotropes](https://durgical.com/en/pharmacology/classes/vasopressors-and-inotropes/)
- [Uterotonics (oxytocin and analogues)](https://durgical.com/en/pharmacology/classes/uterotonics/)

[← All of anaesthesia](https://durgical.com/en/anaesthesia/)

Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: [Massive Transfusion](https://www.ncbi.nlm.nih.gov/books/NBK499929/) (StatPearls (NCBI Bookshelf), 2025); [Permissive Hypotension](https://www.ncbi.nlm.nih.gov/books/NBK558915/) (StatPearls (NCBI Bookshelf), 2024).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anaesthesia/massive-haemorrhage-in-theatre/