Quality Assurance

External quality assessment challenges arrive from a provider several times a year and must travel through the transfusion service exactly as patient samples do — the same staff, the same reagents, the same instruments and the same interpretation rules. Steering survey work to the most experienced technologist, or repeating it until the answers agree, hides how the centre actually performs. Results go back on the provider's form before the deadline, worksheets are kept, and when the report returns the centre's grading is compared with the consensus. Any graded discrepancy triggers a documented investigation — reagent lot, technique, transcription — with corrective action and follow-up.

[IMAGE] summarises how a hospital transfusion service graded on the five samples of the most recent ABO and D survey. Three samples agreed with the consensus and two did not. Once this report reaches the laboratory, what best meets the service's obligation?

ARequest a regrade from the survey provider promptlyBInvestigate the cause and record corrective actionCRetest the survey sample and file the new resultDNote the score and review at the next cycle

A survey box arrives holding three plasma samples for antibody identification. The charge technologist wonders how they should be worked up so the exercise tells the centre something useful about its own performance. Which approach does that?

ATest them on the routine bench by the usual methodBAssign them to the most experienced technologistCExtend the incubation to maximise antibody pickupDShare the reactions with a neighbouring hospital lab

Every reagent that stands behind a patient result must be shown to work on the day it is used. In a transfusion service that means daily reactivity checks: anti-A, anti-B and anti-D against cells known to carry and to lack the antigen, reagent red cells checked against weak antisera, and anti-human globulin confirmed with IgG-sensitised cells. You look for the expected reaction strength, a genuinely negative negative, and no haemolysis or turbidity in the vial. Calibration counts too — serofuge spin time, cell washer volumes, incubator temperature and reader settings all have to be current before results leave the bench.

Errors behave differently, so the response differs. Random error shows up as one-off outliers and widening scatter — a bubble trapped in a gel column, a thin cell suspension, a tube washed short — and it is usually settled by a careful repeat. Systematic error pushes results one way: a shift, where the control jumps to a new level and stays there after a lot change or a service call, and a trend, where grades creep run after run as antisera weaken or an incubator drifts. Charting control reactions every day is what makes either pattern visible before a patient is affected.

A transfusion service charts the reaction grade of its anti-A control cell each morning and reviews the plot weekly. [IMAGE] covers the last nine working days, with every point falling to one side of the mean. Which pattern is shown?

AA shift, from a systematic changeBRandom scatter within stated limitsCA trend from reagent deteriorationDAn isolated outlier needing a repeat

Review of the anti-B control shows the recorded reaction grade creeping steadily in one direction across fifteen runs, still inside the acceptable range. Nothing on the bench has been changed in that period. Which cause best explains this behaviour?

AOne under-filled cell suspension tubeBA single mislabelled control tubeCA change of reagent lot last weekDGradual loss of antisera potency

A transfusion service holds perishable stock — red cells dated in weeks, platelets in days, thawed plasma in hours. You set minimum and maximum levels by group against local demand and the surgical list, issue the oldest compatible unit first so stock ages into use rather than into the bin, and watch outdate and wastage rates as indicators. Reagents and gel cards need the same discipline: inspect on receipt, store at the stated temperature, record lot and expiry, open the oldest lot first, and reject any vial showing haemolysis or turbidity. Group O D-negative red cells are the scarcest line and need active stewardship.

Transfusion records are a safety system rather than paperwork. Before a group is reported, the current type is checked against the historical ABO and D result held in the laboratory system, and a mismatch stops the release until identity is resolved on a fresh sample. Antibody records are permanent: a specificity such as anti-Jka can fade below the detection limit yet still drive a delayed haemolytic transfusion reaction, so the history must be flagged where it cannot be overlooked. Traceability links every donor unit number to its recipient and to its fate — transfused, returned or discarded — and those records are retained for decades.