MLT GlobeBlood Banking: General
12 Blood Banking MCQs on General with answers and explanations.
Anti-human globulin (Coombs) reagent is needed mainly to detect:
IgG ('incomplete') antibodies sensitise red cells but are too small to bridge them; AHG cross-links the bound IgG to produce visible agglutination.
When an antibody binds red cells and activates complement to completion, the cells rupture and release haemoglobin. This reaction end-point is called:
Formation of the membrane attack complex lyses red cells, which is read as haemolysis and is a positive reaction. Sensitisation is only antibody coating.
Anti-A and anti-B found in people never exposed to foreign red cells are described as:
ABO antibodies arise without red-cell exposure, probably from environmental antigens resembling A and B; they are mainly IgM. Immune antibodies need transfusion or pregnancy.
The most important clinical use of HLA typing is:
HLA matching reduces graft rejection and graft-versus-host disease. It also helps select platelets for refractory patients, but transplantation is its principal use.
Giving a patient stored blood equal to or exceeding their whole blood volume within 24 hours is termed:
Massive transfusion is classically replacement of one blood volume (about 10 units in an adult) in 24 hours, bringing risks of dilutional coagulopathy, hypothermia and citrate toxicity.
A trauma patient receives synthetic colloids and balanced salt solutions in the resuscitation room. Their purpose is:
Crystalloids and colloids restore volume and perfusion but carry no oxygen, platelets or coagulation factors.
Collecting and later reinfusing a patient's own blood is known as:
Autologous transfusion (pre-deposit, haemodilution or salvage) avoids alloimmunisation and many infectious risks.
HLA antibodies, typically formed after pregnancy or transfusion, are chiefly of which class?
Alloimmunisation to HLA produces mainly IgG antibodies, which cause platelet refractoriness, febrile reactions and transplant rejection.
Which condition is typically associated with WARM rather than cold autoimmune haemolytic anaemia?
SLE (and CLL, methyldopa) cause IgG warm AIHA. Mycoplasma (anti-I) and EBV (anti-i) trigger cold IgM autoantibodies; lymphomas can cause either type.
Which haemostatic problem is the most frequent consequence of massive transfusion with stored red cells and crystalloid?
Stored red cells contain few viable platelets or labile factors, so replacing a blood volume dilutes platelets and clotting factors. Citrate load causes hypocalcaemia, not hypercalcaemia.
Which change speeds up antibody uptake onto red cells in antibody-screening tests?
Low-ionic-strength solution reduces the ion cloud around cells, increasing antibody association and allowing shorter incubation. pH, temperature and time also influence binding.
How does the indirect antiglobulin test (IAT) differ from the direct test (DAT)?
In the IAT, patient plasma is incubated with reagent cells at 37 °C before adding AHG; the DAT tests the patient's own cells directly.