Blood Type and Surgery: What Happens Pre-Op

The pre-operative type-and-screen

For elective surgery with potential for blood loss, the patient typically has a pre-operative type-and-screen. The blood sample is sent to the hospital transfusion laboratory, which determines ABO and Rh-D type and screens for clinically significant antibodies (using indirect antiglobulin technique against a panel of standard reagent red cells).

A negative antibody screen and a known ABO/Rh-D allow the lab to issue compatible blood quickly through electronic crossmatch (computer comparison of donor unit type against patient type, no further serological testing needed). The test result is typically valid for several days for a stable inpatient and for 72 hours for an ambulatory pre-op patient, after which the type-and-screen may need to be repeated to ensure no new antibodies have developed.

A positive antibody screen prompts antibody identification and the issuing of antigen-negative blood for transfusion. This can take longer (hours to days) and may require referral to a regional blood centre for unusual antibodies. Patients with known historical antibodies have this in their record so it can be planned for in advance.

The maximum surgical blood ordering schedule (MSBOS)

MSBOS protocols are local hospital agreements that specify the recommended blood reservation for each common surgical procedure. They are based on actual transfusion rates in audit data: the number of units a patient with that procedure typically requires.

For low-bleeding-risk procedures (laparoscopic cholecystectomy, total knee replacement, transurethral prostate resection), the MSBOS recommendation is type-and-screen only; no units are physically reserved. For higher-risk procedures (cardiac surgery, major hepatic resection, complex aortic surgery, liver transplant), specific numbers of crossmatched units are reserved.

The MSBOS approach reduces unnecessary blood holding (which wastes blood that expires unused), shortens the laboratory turnaround time, and saves cost. It is part of standard UK JPAC transfusion practice and is reflected in AABB guidance.

Patient blood management (PBM)

Patient blood management is an evidence-based approach to managing the patient's own blood through the surgical pathway. It has three pillars: optimise red cell mass before surgery, minimise blood loss during surgery, and use restrictive transfusion thresholds after surgery.

Pre-operative optimisation includes detecting and treating iron deficiency anaemia (oral or intravenous iron, with several weeks lead time), correcting other reversible anaemia causes (B12, folate), and addressing any reversible causes of bleeding tendency (anticoagulation review). For elective major surgery, NICE NG24 recommends pre-op haemoglobin optimisation as part of routine practice.

Intra-operative blood conservation includes cell salvage, antifibrinolytic drugs (tranexamic acid, demonstrated benefit in major surgery and trauma in CRASH-2 and other trials), maintenance of normothermia (cold patients bleed more), surgical technique optimisation, and use of viscoelastic point-of-care testing (TEG, ROTEM) to guide replacement of specific clotting factors.

Post-operative practice includes restrictive haemoglobin thresholds for transfusion (typically 70-80 g/L for stable patients, higher for cardiac patients, individualised by clinical context) and continued iron repletion in the recovery period.

Cell salvage and autologous transfusion

Intra-operative cell salvage is now widely used in cardiac surgery, major orthopaedic surgery, complex vascular surgery, liver transplant, and major obstetric surgery. The cell saver collects blood lost into the surgical field, washes the red cells with saline, and returns the concentrated washed red cells to the patient. The donor and recipient are the same person; ABO incompatibility is not an issue.

Cell salvage avoids the immunological risks of donor transfusion (alloimmunisation, transfusion-related acute lung injury, transfusion-associated circulatory overload), the infection risks (small but not zero), and the supply pressures on the donor blood bank. It does not work well in fields contaminated by cancer cells (theoretical risk of disseminating cancer), gross infection, or amniotic fluid.

Pre-operative autologous donation (where the patient gives blood for their own future surgery in advance) was widely used in the 1990s but has fallen out of favour. The patient's haemoglobin drops with each donation and may not recover before surgery, increasing the chance of transfusion overall. Modern PBM principles emphasise iron repletion and cell salvage instead.

Emergency surgery without a known type

For emergency surgery in a patient with no known blood type and no time for typing, the universal donor principle applies. O-negative red cells are given to women of childbearing potential; O-positive red cells are commonly given to men and post-menopausal women (avoiding sensitisation risk only matters for women who could become pregnant). AB plasma is the universal plasma donor and is given alongside red cells in the early phase of major haemorrhage.

Once the patient's ABO/Rh-D type is known (typically within 30-60 minutes of arrival), type-specific blood is issued. The trauma resuscitation transitions from O-negative emergency products to type-specific products as the laboratory work catches up.

See our O-negative donation need page for the supply implications of this universal-donor practice and our component therapy page for the reintroduction of low-titre group O whole blood (LTOWB) in modern trauma resuscitation.

If you have rare antibodies or complex transfusion history

Patients with rare red cell antibodies (Vel, U, Js-b, certain Rh variants) need antigen-negative blood that may take days to source. For elective surgery, advance planning with the hospital transfusion laboratory and the regional rare donor programme is essential. Pre-operative autologous donation has a clearer role in this small group of patients.

Patients with multiple historical antibodies, sickle cell disease on chronic transfusion, or thalassaemia major often have established transfusion plans coordinated by haematology and transfusion medicine teams. Surgery in these patients requires advance liaison with those teams.

The Royal College of Anaesthetists and the American Society of Anesthesiologists publish guidance on perioperative blood management for complex patients.

Frequently asked questions

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