Surgical bleeding, coagulopathy and blood products

• Most surgical bleeding is first dealt with by the surgeon, not by transfusion: control the vessel, keep the patient warm, correct acidosis and hypocalcaemia, and only then replace what was lost.
• Decide the blood product from the defect, not from the colour of the blood: red cells for haemoglobin, platelets for number and function, plasma or cryoprecipitate for clotting factors and fibrinogen.
• Tiny red-cell volume matters. Even 10 to 50 mL of ABO-incompatible red cells can be fatal ^[4], so identity checks at the bedside are part of haemostasis, not paperwork.
• Anticoagulants and antiplatelets are managed by timing, not by fear. Warfarin usually stops 3 to 5 days before surgery ^[2], the direct oral anticoagulants 1 to 5 days depending on renal function ^[2], and bridging is mostly unnecessary.
• Tranexamic acid is cheap and simple: 1 g by slow intravenous injection just before surgery for adults ^[3], in any operation where the skin or mucous membranes are breached and there is any bleeding risk.

By the end of this page you should be able to:

1. Assess bleeding risk before surgery from the history, the operation, the comorbidities and the haemostasis screen.
2. Plan when to stop and when to restart warfarin, direct oral anticoagulants, heparin and antiplatelet drugs around an operation.
3. Choose the right blood component, give its dose and recheck the target laboratory value afterwards.
4. Use tranexamic acid and intraoperative cell salvage correctly and safely.
5. Recognise the main transfusion reactions, stop the transfusion in the correct order and arrange the right investigations.
6. Explain the ABO and Rh(D) compatibility rules for red cells, platelets and plasma.

Haemorrhage is the complication every surgeon prepares for and the one most often underestimated. Blood loss that exceeds what the procedure should produce is not only a surgical problem: it dilutes clotting factors, cools the patient, activates fibrinolysis and turns a controlled operation into an emergency. The aim of this pathway is to prevent the bleeding that can be prevented (correct anaemia and coagulopathy before the day of surgery, time the antithrombotic drugs properly, give tranexamic acid), to replace what is lost in the most physiological way (components chosen for the actual defect, restrictive red cell use) and to catch the rare but catastrophic errors (ABO incompatibility, the wrong patient).

The guidance named here is the newest each major body publishes in an open form: the 2023 AABB International Guidelines for red blood cell transfusion. ^[1], the NICE guideline on blood transfusion NG24 (published 2015, last updated 26 February 2026). ^[3], the European Society of Anaesthesiology and Intensive Care (ESAIC) guidelines, second update 2022. ^[2] For the reactions that can turn a transfusion into a catastrophe, the International Society of Blood Transfusion (ISBT) module on adverse effects of transfusion is the reference. ^[4]

Bleeding risk is the balance between three things: the patient's haemostatic reserve, how much bleeding this operation produces, and what antithrombotic drugs are on board. It should be documented before every moderate or major procedure.

Ask directly and write the answer down. A personal or family history of abnormal bleeding (nosebleeds, gum bleeding, heavy periods, prolonged bleeding after cuts or dental work, postpartum haemorrhage) and a family history of haemophilia or von Willebrand disease point to an inherited disorder, which is managed with a haematologist. ^[2] Liver disease, chronic kidney disease, severe malnutrition, myeloproliferative disease and splenomegaly each distort haemostasis in different ways. Recent or chronic infection, disseminated intravascular coagulation and massive trauma are part of the consumptive picture. Drugs are the commonest iatrogenic cause: warfarin and other vitamin K antagonists, the direct oral anticoagulants, unfractionated and low-molecular-weight heparin, fondaparinux, aspirin, clopidogrel, prasugrel, ticagrelor, non-steroidal anti-inflammatory drugs and several herbal preparations.

A full blood count with platelets, a prothrombin time with international normalised ratio (INR), an activated partial thromboplastin time (APTT), fibrinogen, creatinine and liver function, plus a group and screen, is the sensible baseline for major surgery. Abnormal standard tests do not always mean bleeding (chronic liver disease, for example, can be "auto-anticoagulated" with a balanced haemostasis), but they do require explanation before the incision. ^[2]

Two scores from the perioperative anticoagulation literature are useful mental models and are quoted by the bleeding-risk assessment literature. ^[5]

• HAS-BLED: Hypertension, Abnormal renal or liver function, Stroke, Bleeding history or predisposition, Labile INR, Elderly over 65 years, Drugs or alcohol concomitantly. Developed for the non-operative setting, it has been shown to predict bleeding during bridging of chronic anticoagulation. ^[5]
• BleedMAP: a four-item score (history of bleeding, a mechanical heart valve in the mitral position, active cancer, thrombocytopenia) that correlates with periprocedural bleeding.

They are not substitutes for local risk assessment, but they force you to list the hazards instead of guessing. ^[5]

Procedures sort into low, intermediate and high bleeding risk. Low-risk work (minor dental, minor dermatological, cataract and avascular endoscopy) rarely needs anticoagulation interrupted at all. ^[5] Intermediate and high-risk work (major vascular and cardiac, major abdominal and pelvic cancer surgery, major orthopaedic, neurosurgery and spinal surgery, renal and hepatic surgery, complex pelvic reconstruction) is where the plan matters. Highly vascular organs (liver, kidney, spleen) bleed for anatomical reasons even in a patient with completely normal haemostasis. ^[5] Neuraxial and intracranial operations are special: the bleeding risk of the procedure itself may be modest, but the consequences of a small haematoma are severe. ^[2]

The ESAIC guidelines define severe bleeding as a peri-interventional blood loss of more than 20% of the blood volume ^[2], and exclude trauma from that definition. ^[2]

Preoperative anaemia is one of the strongest predictors of needing a transfusion. Assess everyone at risk of bleeding well before the operation, identify the cause (iron deficiency, renal insufficiency, inflammation), and treat iron deficiency with weight-based iron supplementation, preferring intravenous over oral when oral is not tolerated, not absorbed, or there is not enough time before surgery. ^[2] For uncomplicated iron deficiency, oral correction needs 3 to 8 weeks, and parenteral stimulation of erythropoiesis with an uncomplicated cause 1 to 2 weeks. ^[2] In non-cancer patients with preoperative anaemia booked for elective major surgery, postpone the operation until the anaemia is corrected. ^[2] Do not use a preoperative red cell transfusion to mask mild to moderate anaemia. ^[2]

The decision is always the same three questions: what is the patient's thrombotic risk, what is the procedure's bleeding risk, and how long does this drug take to leave and to return. The drug-specific timings below come from the 2022 ESAIC guideline and from standard texts. ^[2][5]

For dual antiplatelet therapy with a coronary stent placed within the last 3 to 12 months and elective surgery planned, stop the P2Y12 inhibitor before surgery and continue aspirin. Non-cardiac elective surgery should be postponed until the full course of dual antiplatelet therapy is completed (at least 4 weeks after a bare-metal stent and 3 to 6 months after a drug-eluting one). For urgent or semi-urgent surgery, try to operate under aspirin plus a P2Y12 inhibitor, or at least under aspirin alone, and decide this in a multidisciplinary meeting. ^[2]

Heparin bridging for warfarin and direct oral anticoagulants is not recommended as routine because trials show it increases major bleeding without a clear reduction in thromboembolism. ^[2][5] Bridging with intravenous glycoprotein IIb/IIIa inhibitors or cangrelor may be considered for high-ischaemic-risk patients on dual antiplatelet therapy when interruption of a P2Y12 inhibitor is unavoidable. ^[2]

Give a component for the problem it fixes, not as a ritual. Red cells restore oxygen delivery, platelets restore the plug, and plasma or cryoprecipitate restore the soluble clotting factors and fibrinogen.

The 2023 AABB International Guidelines (45 randomised trials, 20 599 participants) recommend a restrictive strategy. ^[1] NICE NG24 comes to the same conclusion with a threshold of 70 g/L. ^[3]

• In haemodynamically stable hospitalised adults, transfuse when haemoglobin falls under 7 g/dL (70 g/L), with a target of 70 to 90 g/L after transfusion. ^[1][3]
• For cardiac surgery a threshold of 7.5 g/dL (75 g/L) is acceptable, for orthopaedic surgery or pre-existing cardiovascular disease 8 g/dL. ^[1]
• For haematologic and oncologic conditions the AABB suggests transfusing under 7 g/dL. ^[1]
• For acute coronary syndrome NICE suggests 80 g/L with a target of 80 to 100 g/L. ^[3]
• Major haemorrhage, regular transfusion for chronic anaemia and individual circumstances are handled differently: clinical judgement over a single number. ^[1][3]
• ESAIC recommends a red cell target of 7 to 9 g/dL during active bleeding. ^[2]

Single-unit transfusion is the safest default for adults who are not bleeding, with reassessment and a haemoglobin check after each unit. ^[3] In the first phase of uncontrolled massive bleeding, ESAIC suggests a high ratio of plasma to red cells, at least 1 to 1, then switching to goal-directed therapy guided by the full blood count, coagulation tests and viscoelastic testing as soon as bleeding is under control. ^[2]

• A count under 30 x 10^9/L in a person with clinically significant bleeding justifies platelet transfusion; up to 100 x 10^9/L for severe bleeding (World Health Organization bleeding grades 3 and 4) or bleeding in critical sites such as the central nervous system. ^[3]
• Without bleeding, transfuse prophylactically under 10 x 10^9/L. ^[3]
• For invasive procedures or surgery, raise the count above 50 x 10^9/L, or 50 to 75 x 10^9/L for a high bleeding risk, and above 100 x 10^9/L for surgery in critical sites such as the central nervous system or the posterior segment of the eye. ^[3]
• Do not transfuse more than one dose routinely; reassess the count after each dose. ^[3]
• Do not transfuse prophylactically in chronic bone marrow failure, autoimmune thrombocytopenia, heparin-induced thrombocytopenia or thrombotic thrombocytopenic purpura, and not for very low bleeding-risk procedures. ^[3]

ESAIC adds the quality point of view for perioperative bleeding: platelets are not first-line for a low platelet count unless there is bleeding or a planned procedure. ^[2]

• Consider fresh frozen plasma (FFP) only when there is clinically significant bleeding without major haemorrhage and the PT ratio or APTT ratio is above 1.5. ^[3]
• Do not use it to correct an abnormal coagulation screen in someone who is not bleeding, unless an invasive procedure with a risk of clinically significant bleeding is planned, and do not use it to reverse warfarin. ^[3]
• Reassess the clinical state and repeat coagulation tests after transfusion. ^[3]
• In cardiac surgery, ESAIC suggests PCC instead of FFP when there are signs of coagulation factor deficiency. ^[2]

• Consider cryoprecipitate for a person who is bleeding (without major haemorrhage) whose fibrinogen is under 1.5 g/L, or prophylactically under 1.0 g/L when an invasive procedure or surgery carries a risk of clinically significant bleeding. ^[3]
• Adult dose 2 pools (children 5 to 10 mL/kg, maximum 2 pools); reassess fibrinogen after. ^[3]
• ESAIC recommends treating hypofibrinogenaemia of 1.5 g/L or less, during active bleeding, with fibrinogen concentrate or cryoprecipitate. ^[2]
• ESAIC also notes that in cirrhotic patients, levels under 2 g/L may identify those at risk of severe postpartum haemorrhage, and that fibrinogen should be checked in bleeding patients with liver disease. ^[2]

Cell salvage returns the patient's own red cells during surgery and cuts allogeneic transfusion. It is useful, but it is not a free transfusion.

• NICE recommends considering intraoperative cell salvage with tranexamic acid when very high blood loss is expected (cardiac and complex vascular surgery, pelvic reconstruction, scoliosis). It should not be used routinely without tranexamic acid. ^[3]
• ESAIC recommends cell salvage as helpful for blood conservation in major cardiac surgery, and suggests intraoperative and postoperative cell salvage in major orthopaedic procedures with a high risk of bleeding. ^[2]
• Cell salvage is not contraindicated in cancer surgery provided blood is not aspirated close to the tumour site and leukodepletion filters are used; it can also be used in liver transplantation, including hepatocellular carcinoma, with leukodepletion filters. ^[2]
• In obstetric surgery, cell salvage is well tolerated when precautions are taken against rhesus isoimmunisation, and it may decrease allogeneic transfusion during caesarean section with a high risk of haemorrhage. ^[2]
• Autologous blood donation with concomitant iron and erythropoietin is suggested to avoid preoperative anaemia. ^[2]

Tranexamic acid is an antifibrinolytic: it blocks plasminogen activation and preserves clot. The NICE 2026 update makes it a routine offer rather than a consideration.

• Offer tranexamic acid to adults having surgery in an operating theatre if there is any risk of bleeding and the procedure breaches the skin or mucous membranes. Give it just before the start of surgery, typically 1 g by slow intravenous injection. ^[3]
• Offer it to adults having surgery outside an operating theatre (for example interventional radiology or the emergency department) who are expected to lose more than 500 mL of blood. ^[3]
• For children aged 1 to 15 years consider it on the same first criterion, and give 15 mg/kg (maximum 1 g) by slow intravenous injection just before surgery; outside theatre, consider it when expected loss exceeds 10% of blood volume. ^[3]
• If more than one dose might help because of length of surgery or blood loss, balance the benefit against the risk of accumulation, particularly in renal impairment. ^[3]
• Put safety measures in place to prevent accidental intrathecal or epidural administration rather than intravenous administration. ^[3]
• ESAIC recommends prophylactic tranexamic acid before cardiopulmonary bypass, at low intravenous doses, with topical application when systemic administration is contraindicated (for example refractory seizure). ^[2]
• In orthopaedic surgery ESAIC recommends prophylactic tranexamic acid for patients with a relevant bleeding risk, by oral, intravenous or topical routes, or a combination of systemic and topical. ^[2]
• In gynaecological surgery the ESAIC recommended dose is a single 1000 mg intravenously, or 10 to 15 mg/kg, or topical. ^[2]
• Do not use systemic tranexamic acid for gastrointestinal bleeding (upper gastrointestinal haemorrhage). ^[2]
• Avoid prophylactic tranexamic acid in COVID-19 coagulopathy and in suspected fibrinolytic shutdown in critical illness. ^[2]
• Tranexamic acid can be considered in cirrhotic patients undergoing liver resection and in prostate or percutaneous nephrolithotomy surgery to reduce perioperative blood loss. ^[2]

NICE 2015 still advises considering cell salvage with tranexamic acid for very high loss, and the NICE review of evidence underpins the updated tranexamic acid recommendation. ^[3]

Every reaction is cheaper to prevent than to treat. Monitor the patient's condition and vital signs before, during and after every transfusion, and transfuse only where staff are able to monitor and manage acute reactions. ^[3] Consider electronic patient identification systems, which improve the safety and efficiency of the transfusion process. ^[3] At the ISBT level, the message is identical: any sign or symptom temporally related to a transfusion warrants investigation. ^[4]

Cross-check at the bedside before starting: confirm the patient's identity against the wristband and the compatibility label, match the unit to the request, inspect the pack for clumps, particles or discolouration, and if any mismatch or damage is found do not transfuse and call the transfusion laboratory. ^[4] The most common cause of an ABO-incompatible transfusion is human error (labelling, sample collection, bedside checks). ^[4]

For red cells, ABO compatibility is determined by the recipient's antibodies: group O recipients can receive only O red cells; group A recipients can receive A or O; group B recipients can receive B or O; group AB recipients (the universal recipients for red cells) can receive A, B, AB or O. Group O, Rh(D)-negative donors are the universal red cell donors in an emergency. Plasma compatibility runs the other way: group AB plasma can be given to any recipient and group O plasma only to group O recipients. Group-compatible (or at least group-compatible, Rh(D)-negative) red cells should be used whenever possible. ^[4] NICE also places a high value on appropriate consent and information sharing around transfusion. ^[3]

Rh(D) matters as much as ABO. Rh(D)-negative red cells should be given to Rh(D)-negative patients, and particularly Rh(D)-negative girls and women of childbearing age, to prevent sensitisation.

Isolated hypotension (a fall in systolic and/or diastolic pressure of more than 30 mmHg with a systolic pressure under 80 mmHg, within an hour, without allergic symptoms) can occur, especially in patients on ACE inhibitors; it usually requires only minor intervention and is a diagnosis of exclusion. ^[4]

The order is fixed and quick: stop the transfusion, keep venous access open with 0.9% normal saline, check the identity details on the patient, the wristband and the compatibility label, call a doctor, assess the airway, breathing and circulation and give oxygen, take the blood unit and giving set and send post-transfusion samples, then start specific treatment guided by the most likely reaction without waiting for all the results. Initial treatment of a severe reaction must not be delayed until investigations return. ^[4][3]

Both cause acute breathlessness during or shortly after transfusion and are hard to tell apart at first. TRALI is non-cardiogenic pulmonary oedema, typically within 6 h, and the patient is often hypovolaemic; TACO is cardiogenic overload and patients have risk factors (congestive heart failure, renal dysfunction, older age) with a large transfused volume. A B-type natriuretic peptide (BNP) or N-terminal pro-BNP that rises to more than 1.5 times the pre-transfusion value supports TACO, and patients with TACO usually respond to diuretics while TRALI does not. The two can coexist. ^[4]

A cross-match (serological compatibility test between patient plasma and donor red cells) and an antibody screen are the laboratory side of the cross-check. If the screen is positive, the antibody is identified and antigen-negative, cross-match-compatible units are selected. The direct antiglobulin test helps investigate suspected haemolysis. Careful pre-transfusion sample collection, bedside labelling before leaving the patient and the bedside identity check in theatre are what prevent the fatal error; no amount of laboratory cleverness fixes a wrong sample taken at the trolley. ^[4]

• The single most useful investigation in a surgical patient who is bleeding is the haemoglobin, platelet count, INR/APTT and fibrinogen, if available; a group and screen or full cross-match is essential before non-urgent transfusion.
• Where viscoelastic testing, fibrinogen concentrate, PCC and platelets are scarce, correct the basics: warm the patient, control surgically, give tranexamic acid early, transfuse red cells and whole blood or plasma according to availability, and use the minimum effective component dose.
• In maternity and tropical settings, consider the special causes of coagulopathy (placental abruption, sepsis, liver disease, snake envenomation) rather than assuming a simple consumptive picture.
• Rh(D)-negative inventory is often limited; reserve it for women of childbearing age, girls and other patients who clearly need it.
• Patient identification and the bedside identity check cost nothing and prevent the most lethal error; do not skip them when staffing is short.

• Surgical bleeding becomes worse when the patient is cold, acidotic and hypocalcaemic; physiology is part of haemostasis.
• Red cells carry oxygen, platelets build the plug, plasma provides clotting factors and cryoprecipitate provides fibrinogen (and von Willebrand factor); choose the component for the defect.
• Restrictive red cell strategy: transfuse under 7 g/dL (70 g/L) in stable adults, 7.5 g/dL after cardiac surgery, 8 g/dL with cardiovascular disease or orthopaedic surgery, target 70 to 90 g/L; 7 to 9 g/dL during active bleeding.
• Single unit red cells when not bleeding, reassess after each.
• Platelets: under 30 x 10^9/L with bleeding, up to 100 x 10^9/L for severe or critical-site bleeding, above 50 x 10^9/L before invasive procedures, prophylaxis under 10 x 10^9/L, one dose at a time.
• Plasma only for bleeding with PT or APTT ratio above 1.5 (not for warfarin reversal); cryoprecipitate for fibrinogen under 1.5 g/L, dose 2 pools.
• Warm the patient, give tranexamic acid early (1 g intravenous in adults; 15 mg/kg maximum 1 g in children), and consider cell salvage with tranexamic acid for expected high loss.
• Warfarin: stop 3 to 5 days before, do not interrupt for low-risk procedures, no routine bridging, restart within 24 h.
• Direct oral anticoagulants: stop 1 to 5 days before depending on the drug and renal function, no bridging, restart according to bleeding risk.
• Aspirin for secondary prevention is continued in most operations; P2Y12 inhibitors need 5 (clopidogrel, ticagrelor) or 7 (prasugrel) days off before elective surgery.
• Heparin reversal: protamine 1 mg per 100 IU for intravenous unfractionated heparin; 1 mg per 100 anti-Xa units for low-molecular-weight heparin.
• Even 10 to 50 mL of ABO-incompatible red cells can kill; identity checks at the bedside prevent it.
• Any sign temporally related to a transfusion deserves an acute reaction work-up, starting with stopping the transfusion while keeping venous access open.
• TRALI arises within 6 h and is non-cardiogenic, TACO is cardiogenic overload and usually responds to diuretics.

• Haemostasis and bleeding disorders (planned)
• Anaemia and red cell disorders (planned)
• Transfusion medicine (planned)
• Warfarin and direct oral anticoagulants (planned)
• Basic perioperative care (planned)