Perioperative blood management

01Core principlesThe concepts and mechanisms needed to understand the subject.

Patient blood management begins before the operation. Its linked aims are to improve the patient’s own red-cell mass, minimise blood loss and use transfusion only when the likely benefit exceeds risk. Anaemia is associated with more transfusion and worse surgical outcomes, but a low haemoglobin is a finding rather than a diagnosis. Early screening permits evaluation for iron deficiency, chronic inflammation, renal disease, B12 or folate deficiency, haemoglobinopathy and ongoing blood loss.

NICE recommends oral iron before and after surgery for iron-deficiency anaemia. Intravenous iron is considered when oral iron is not tolerated, absorbed or adhered to, in functional iron deficiency, or when the interval to surgery is too short for oral treatment to work. Erythropoietin is not routine; the specified exceptions concern an anaemic person who meets transfusion criteria but declines blood or lacks an appropriate type because of antibodies.

Blood conservation continues in theatre. The February 2026 NG24 update broadened adult tranexamic-acid use for operating-theatre procedures that breach skin or mucous membranes and carry any bleeding risk. It is administered just before surgery, typically 1 g slow IV. Additional dosing depends on operation length and loss, balanced against accumulation in renal impairment. Intraoperative cell salvage is considered with tranexamic acid where very high loss is expected.

Transfusion decisions combine bleeding rate, physiology, symptoms, haemoglobin trajectory, comorbidity and alternatives. Restrictive thresholds apply to stable settings, not uncontrolled haemorrhage. A single unit followed by reassessment avoids automatic overtransfusion in a non-bleeding adult. Component support during active major loss follows a coordinated local protocol because early laboratory values lag, dilution evolves and source control is decisive.

Key points

Find anaemia early before major elective surgery, investigate the cause and treat iron deficiency; transfusing an otherwise stable haematinic deficiency exposes the patient to harm without correcting the cause.
For adults having operating-theatre surgery that breaches skin or mucosa and carries any bleeding risk, NICE 2026 says offer tranexamic acid just before surgery, typically 1 g by slow IV injection.
Outside major haemorrhage, acute coronary syndrome and regular chronic-transfusion settings, consider a restrictive red-cell threshold of 70 g/L and target 70–90 g/L; in non-bleeding adults give one unit then reassess and recheck Hb.
For acute coronary syndrome, consider an 80 g/L threshold and 80–100 g/L target. Chronic transfusion needs individual thresholds rather than either generic rule.
Use intraoperative cell salvage with tranexamic acid when very high blood loss is expected; discuss feasibility, contamination, patient preferences and the operation-specific collection plan.
Treat the component deficit, not an isolated abnormal number: platelets, plasma, fibrinogen-containing products and red cells answer different bleeding problems and need clinical context.

02Mechanisms and patternsImportant relationships and how to distinguish them.

Identify anaemia early

Before major surgery, obtain full blood count with indices early enough to investigate iron status, renal function, inflammation, B12, folate, haemoglobinopathy or ongoing loss where indicated.

Estimate procedural loss

Consider operation, revision status, vascularity, duration, anticoagulants, prior radiotherapy, coagulopathy and whether cell salvage and rapid component access are feasible.

Clarify patient preferences

Discuss consent for red cells, plasma, platelets, cell salvage, factor concentrates and fractions individually; document accepted alternatives and an emergency plan rather than assuming from a label.

Recognise active haemorrhageRed flag

Tachycardia, hypotension, altered perfusion, unexpected operative loss, increasing drain output, acidosis, hypothermia and diffuse bleeding require source control and major-haemorrhage coordination.

Recognise transfusion reactionRed flag

Fever, rigors, dyspnoea, chest or loin pain, urticaria, hypoxaemia, hypotension or dark urine during a component may represent an acute reaction and requires immediate cessation and assessment.

Separate threshold exceptions

Major haemorrhage, acute coronary syndrome and chronic transfusion dependence each sit outside the generic 70 g/L threshold and require their specific physiological or individual plan.

Red flags requiring action

Haemodynamic instability, brisk drain or wound loss, diffuse surgical-field bleeding, falling temperature or rising lactate should trigger haemorrhage escalation without waiting for a low haemoglobin result.
A historical antibody, previous transfusion reaction, complex blood group, sickle-cell disease or anticipated massive loss requires early transfusion-laboratory communication because compatible components may take time.
New fever, rigors, dyspnoea, hypoxaemia, hypotension, pain, urticaria or dark urine during transfusion may be an acute reaction: stop the component, keep IV access, assess ABC and contact the laboratory immediately.
Tranexamic acid given by the intrathecal or epidural route can be fatal; storage, labelling and route checks must prevent neuraxial administration.
Active thromboembolic disease, ongoing intravascular clotting or renal impairment changes the benefit-risk and repeat-dose plan for tranexamic acid.
The restrictive 70 g/L red-cell threshold does not apply unchanged to major haemorrhage, acute coronary syndrome or people needing regular transfusion for chronic anaemia.

03Interpreting evidenceInformation, measurements and their limitations.

Reasoning sequence

Consider the information, its meaning and its limitations before deciding what follows.

01
Full blood count and red-cell indices
Why
Detect preoperative anaemia and classify the initial red-cell pattern early enough for cause-directed treatment.
Interpretation and limitations
Microcytosis can support iron deficiency but ferritin and transferrin saturation refine diagnosis; normal cell size does not exclude iron deficiency, renal disease or inflammation.
02
Ferritin and transferrin saturation
Why
Distinguish absolute or functional iron deficiency and select oral versus intravenous replacement.
Interpretation and limitations
Ferritin rises with inflammation, so an apparently normal result may not exclude restricted iron availability; interpret alongside inflammation, renal function and red-cell indices.
03
Group, antibody screen and compatibility testing
Why
Identify blood group and clinically significant antibodies and prepare appropriate components when transfusion is plausible.
Interpretation and limitations
A positive antibody screen can substantially delay compatible supply; notify the laboratory early rather than relying on urgent uncrossmatched provision for planned surgery.
04
Serial haemoglobin and physiological assessment
Why
Track red-cell loss and judge oxygen-delivery consequences before and after transfusion.
Interpretation and limitations
Hb can initially remain near baseline during acute haemorrhage and later fall with redistribution. Integrate bleeding rate, perfusion, lactate, symptoms and cardiac disease.
05
Platelets, PT, APTT and fibrinogen
Why
Characterise evolving haemostatic deficits during significant bleeding and guide component or factor support.
Interpretation and limitations
Results can lag rapid blood loss and are influenced by anticoagulants, dilution, liver disease and temperature; repeat and use point-of-care testing only within a governed algorithm.
06
Bedside and laboratory reaction work-up
Why
Identify incompatibility, haemolysis, sepsis, allergy, lung injury or circulatory overload when symptoms develop during transfusion.
Interpretation and limitations
Stop first and stabilise the patient; clerical and laboratory checks follow. The component must not be restarted until the reaction is assessed and authorised.

04Applied reasoningWorked examples connecting principles to decisions.

01Worked case: elective anaemiaIron deficiency before major bowel surgeryAn adult several weeks before planned major surgery has low haemoglobin, small red cells and biochemical iron deficiency without instability.

1Inform the patient, surgeon and perioperative team, investigate the bleeding and deficiency cause, and assess how surgical urgency constrains the time available for correction.
2Offer oral iron when it can be tolerated and there is enough time; consider intravenous iron when absorption, tolerance, adherence, functional deficiency or a short interval makes oral therapy ineffective.
3Do not use red-cell transfusion simply to treat a stable haematinic deficiency without a separate clinical indication; transfusion adds risk and leaves the cause untreated.
4Recheck haemoglobin response at a clinically useful interval and review ongoing loss, nutrition, renal disease and inflammation if the response is inadequate.
5Document the expected blood-loss plan, consent and preferences, compatibility needs and postoperative transfusion strategy. For this adult operating-theatre surgery that breaches skin or mucosa and carries any bleeding risk, offer tranexamic acid just before surgery, typically 1 g by slow IV injection; consider cell salvage separately when very high blood loss is expected.

02Restrictive transfusion pathwayStable postoperative anaemia without bleedingAn adult is haemodynamically stable after surgery, has no active bleeding or acute coronary syndrome and does not require regular transfusions.

1Assess symptoms, haemoglobin trend, oxygenation, volume status and comorbidity and consider a restrictive threshold of 70 g/L with a post-transfusion target of 70–90 g/L.
2If transfusion is indicated, give one red-cell unit, using an equivalent weight-adjusted volume for a low-body-weight adult where appropriate.
3Clinically reassess and recheck haemoglobin after that unit; give another only when the residual indication outweighs additional exposure.

03Major haemorrhage pathwayActive operative bleeding with shockBlood loss is rapid, physiology is deteriorating or bleeding is expected to exceed routine transfusion support.

1Activate the institution’s major-haemorrhage protocol and coordinate source control, transfusion laboratory, rapid warming, access, sampling and component delivery.
2Use physiology, observed loss and repeated laboratory or governed point-of-care results to direct red cells and haemostatic support; do not wait for the generic 70 g/L threshold.
3Prevent and correct hypothermia, acidosis, hypocalcaemia and dilution while reassessing response, and de-escalate the protocol once bleeding control and stability are secure.

05Relevant medicines and safetySpecific regimens and precautions where medicines are relevant.

Reduces surgical bleeding and transfusion exposure when the procedure breaches skin or mucosa and any bleeding risk exists.

Tranexamic acid for adult theatre surgery

Typically give 1 g by slow intravenous injection just before the start of surgery.

Balance extra doses against accumulation in renal impairment and active thrombosis risk; prevent fatal intrathecal or epidural administration.

Restores iron for erythropoiesis before or after surgery rather than temporarily replacing red cells.

Oral or intravenous iron

Use a cause-specific oral regimen, or a calculated intravenous replacement course when oral therapy is unsuitable or too slow.

Confirm deficiency and investigate its cause; IV products have product-specific dosing and reaction monitoring, and response is limited by ongoing loss or inflammation.

06Checking understandingVerify the reasoning, revisit uncertainties and apply feedback.

After iron treatment, reassess haemoglobin and iron response at an interval that can still influence surgical timing and investigate failure to respond.
During transfusion, record baseline and interval observations and maintain staff and facilities able to identify and manage an acute reaction.
After each single red-cell unit in a non-bleeding adult, reassess symptoms, physiology and haemoglobin before prescribing another.
During major haemorrhage, trend temperature, acid-base status, ionised calcium, haemoglobin, platelets, coagulation and fibrinogen alongside observed loss and perfusion.
At handover, state cumulative components, reactions, antibodies, haemostasis plan, remaining bleeding risk and criteria for repeating tests or escalating.

07Special situationsVariants, exceptions and circumstances that change the usual approach.

Anaemia is a diagnosis prompt

The haemoglobin value identifies risk and reduced reserve, while indices, iron studies, inflammation, renal function and bleeding history identify the treatable mechanism.

Thresholds are contextual

A restrictive threshold supports stable decisions; dynamic haemorrhage, coronary ischaemia, symptoms and chronic transfusion requirements alter the benefit-risk calculation.

One unit creates a checkpoint

Single-unit practice limits avoidable donor exposure and circulatory overload by forcing clinical and laboratory reassessment before treatment continues.

Antifibrinolytic route matters

Tranexamic acid resembles medicines intended for neuraxial use in some settings; system separation and deliberate route checks prevent catastrophic wrong-route injection.

Conservation is multimodal

Early haematinic treatment, meticulous haemostasis, temperature control, antifibrinolysis, cell salvage and selective blood sampling each preserve the patient’s blood.

08Common pitfallsFrequent interpretation and management errors.

01
Waiting until the day before major surgery to identify and investigate anaemia.
02
Using 70 g/L as a trigger during active major haemorrhage or acute coronary syndrome.
03
Automatically ordering two red-cell units for a stable non-bleeding adult without an interim reassessment.
04
Giving tranexamic acid through a neuraxial route or overlooking renal accumulation with extra doses.
05
Transfusing haematinic deficiency without investigating and treating its cause.
06
Assuming refusal of whole blood defines acceptance or refusal of every fraction and conservation technique.

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