Which group is the universal donor of PLASMA? A. O B. A C. B D. AB ANSWER: D — group AB. Why: plasma carries the ANTIBODIES, not the red cells. Group AB has NEITHER anti-A nor anti-B, so its plasma can be given to anyone. THE TRAP: O is the universal RED CELL donor, because O cells carry neither A nor B antigen. But O plasma contains BOTH antibodies, so it is the worst plasma to give to a non-O recipient. Work it from the rule — you carry antibodies against the antigens you lack — rather than memorising "O is the universal donor".

Why is the first pregnancy of a D-negative woman usually unaffected, while a later one may be? ANSWER: because anti-D is ACQUIRED, not present from birth. 1. Unlike ABO antibodies, anti-D appears only after exposure to D-positive red cells. 2. A D-negative woman carrying a D-positive fetus is usually not sensitised during that pregnancy. 3. At DELIVERY, fetal cells enter her circulation and she may produce anti-D. 4. In a LATER pregnancy, that anti-D crosses the placenta and destroys fetal red cells — haemolytic disease of the newborn. PREVENTION: anti-D prophylaxis after a potentially sensitising event stops the antibody forming. This is why the blood group is checked at antenatal booking.

A 19-year-old D-negative woman needs a transfusion. Only D-positive units are immediately available and she is haemodynamically stable. What should be done? ANSWER: obtain D-NEGATIVE blood. Do not give D-positive units to a D-negative girl or woman of childbearing age while an alternative exists. WHY: transfusing D-positive cells may sensitise her. It costs nothing today and may cause haemolytic disease of the newborn in a future pregnancy. SHE IS STABLE, so there is time to obtain the correct units. THE EXCEPTION: in a life-threatening haemorrhage with no D-negative blood available, saving her life takes precedence — but that is a decision made knowingly, not by default.

Why is voluntary unpaid donation safer than paid donation when every unit is screened anyway? ANSWER: because of the WINDOW PERIOD. A recently infected donor is already infectious but has not yet developed detectable markers, so screening returns a NEGATIVE result on genuinely infectious blood. DONOR SELECTION IS THE OTHER HALF OF THE DEFENCE: VOLUNTARY UNPAID no incentive to conceal a risk factor when the screening questionnaire asks PAID payment creates an incentive to answer whatever way secures the donation REPLACEMENT DONATION (family must find donors) sits between the two: it applies social pressure to people who may feel unable to decline or disclose. Testing and selection are COMPLEMENTARY, not alternatives.

Where do most fatal haemolytic transfusion reactions originate, and what prevents them? ANSWER: at the BEDSIDE, as identification errors — not in the laboratory. TYPICAL ERRORS: - A sample labelled with the wrong patient's details. - A correctly labelled unit given to the wrong patient. WHAT PREVENTS THEM: 1. Label the sample AT THE BEDSIDE from the wristband, immediately after taking it — never in advance, never at the desk. 2. Ask a conscious patient to STATE their own name and date of birth. Do not ask "are you Mr Sharma?" — a confused or deaf patient agrees. 3. Perform the final check at the patient's side, matching unit to wristband, EVERY time, including the second and third units. The safeguards are procedural, not technological.

Why must the diagnosis of death be kept entirely separate from the question of organ donation? ANSWER: to protect the patient, the family and public confidence in the transplant system. 1. Death is determined by clinicians with NO involvement in transplantation, on purely clinical grounds. 2. Only after death has been diagnosed and explained is donation discussed. 3. Any suggestion that a potential donor's care or diagnosis was influenced by the need for organs would destroy public trust — and lost trust costs lives later through reduced donation. ON BRAIN DEATH: it IS death — irreversible loss of brain-stem function, not a coma and not a prognosis. The heart may beat while a ventilator supplies oxygen, which is why families find it hard: the person looks asleep and feels warm. A family who has not understood that their relative has died cannot meaningfully consent to anything.

A stable patient has mild iron deficiency anaemia and no bleeding. Should they be transfused? ANSWER: No. Treat the CAUSE. 1. Blood is a scarce donated resource, not a tonic. 2. Transfusion exposes a stable patient to risk — including the identification errors above — for little benefit. 3. Iron deficiency responds to iron and to treating the source of loss, which also addresses why the patient became anaemic. 4. The unit used is a unit unavailable to someone who needed it. RELATED PRINCIPLE — COMPONENT THERAPY: whole blood is separated so one donation treats several patients, each receiving only the component they need, rather than everyone receiving everything.