Irradiated, CMV-negative and washed blood components

Special components are not a hierarchy of superior blood. Each modification addresses a different biological hazard and can add delay, reduce component quality or consume scarce stock. Start by naming the risk: viable donor lymphocytes causing TA-GVHD, cell-associated CMV transmission or plasma protein causing recurrent severe allergy. Then select only the relevant modification. Leucodepleted, irradiated, CMV-negative and washed are not interchangeable labels, and a patient can require more than one concurrently.

Irradiation exposes cellular components to validated ionising radiation, preventing donor T lymphocytes from proliferating. This prevents TA-GVHD but does not sterilise the unit or remove leucocytes, CMV, IgA or red-cell antigens. Red cells, platelets and granulocytes may need irradiation; frozen plasma and cryoprecipitate do not contain viable lymphocytes requiring it. Irradiation increases red-cell membrane potassium leakage and shortens allowable storage, so neonatal and hyperkalaemia-sensitive use follows specific age-of-unit and timing rules managed by the laboratory.

Some irradiation indications depend on the component, not the patient's diagnosis. All cellular donations from a first- or second-degree relative require irradiation because shared HLA can permit donor lymphocyte engraftment even in an immunocompetent recipient. HLA-selected platelets also require irradiation, as do granulocytes. Cellular components used for intrauterine transfusion are irradiated, and subsequent neonatal cellular transfusion follows the BSH neonatal window. These requirements apply even when the unit is leucodepleted.

Disease and treatment indications vary in duration. Hodgkin lymphoma carries an indefinite requirement regardless of treatment stage. Purine analogues such as fludarabine, cladribine, deoxycoformycin and bendamustine generally create an indefinite requirement; alemtuzumab and selected potent T-cell therapies require protocol-specific cover. Do not infer safety because treatment occurred years ago. Conversely, acute leukaemia, most non-Hodgkin lymphoma and solid tumours do not require irradiation solely by diagnosis, although transplantation, CAR-T or a particular medicine may add it.

For stem-cell procedures, the treating service must communicate a dated plan. Irradiated cellular components are generally required from before stem-cell collection and conditioning, through the period after autologous or allogeneic transplant defined by BSH criteria. Allogeneic support continues at least six months and longer while immunosuppression, chronic graft-versus-host disease or inadequate lymphocyte recovery persists. Autologous support generally continues at least three months, extended to six months after total-body irradiation. CAR-T recipients need irradiation from seven days before and during lymphocyte collection until three months after infusion unless another indication lasts longer.

CMV resides predominantly in leucocytes. Universal prestorage leucodepletion substantially reduces transfusion-transmitted CMV, and SaBTO considers it adequate for most recipients, including CMV-seronegative stem-cell and solid-organ transplant patients. Additional CMV-negative selection remains for high-consequence groups: intrauterine transfusion, neonates until 28 days after the expected delivery date and CMV-seronegative recipients of granulocytes. The laboratory also follows component specifications for neonatal exchange and other fetal support.

For pregnant patients who require recurrent elective red-cell or platelet transfusion during pregnancy, SaBTO advises CMV-negative components where possible regardless of CMV serostatus. This does not include routine labour or delivery support, and emergency transfusion should not be delayed if CMV-negative stock is unavailable; standard leucodepleted blood is acceptable. CMV antibody testing is not required simply to release emergency blood. Record gestational context and expected delivery date because the neonatal CMV window uses the expected rather than actual delivery date.

Washing repeatedly suspends cellular components in saline to remove most donor plasma. Its main role is preventing recurrent severe allergic reactions when ordinary measures are inadequate, and selected transfusion support for IgA-deficient recipients with anti-IgA and an attributable severe reaction. Isolated IgA deficiency without a reaction does not automatically demand washed blood. Discuss testing and component choice with transfusion medicine because UK IgA-deficient donor components and washed products have different availability and urgency implications.

Washed components have practical limitations. Processing can reduce red-cell or platelet recovery, activates or damages cells and produces a short expiry that increases wastage and bacterial-risk constraints. They require planned ordering and close coordination of collection and administration time. In exsanguination or critical anaemia, a standard component given with full resuscitation readiness may be safer than prolonged delay; the transfusion consultant documents the risk-benefit decision and arranges the preferred product for continuing support.

Communication is part of treatment. The haematology, oncology, transplant or immunology team defines the indication and dates; the transfusion laboratory applies a durable flag; the clinical team confirms the requirement before sampling and prescription; and the patient carries an alert. At every transfer reconcile irradiation, CMV and washing separately. When a time-limited indication ends, only an authorised specialist should remove it after checking whether another lifelong indication coexists.