Question 1

A field service engineer has just replaced the optical flow cell in a haematology analyser. Both levels of quality control recover within range on the first run afterwards, and the technologist has a bench full of waiting samples. What should be done before patient results are released?

Accepted Answer

Recalibrate the analyser with fresh calibrator — Replacing a component in the measuring path changes the relationship between signal and reported value, so calibration status is no longer valid regardless of how the controls behave. Controls sit at only two points and have wide enough limits to mask a modest shift. Calibration with assigned material re-establishes that relationship, and quality control is then repeated to verify it.

Question 2

At morning start-up an impedance cell counter reports a white cell background count of 0.4 ×10⁹/L, above the manufacturer's stated ceiling of 0.2 ×10⁹/L. Reagent containers are full and in date, and the diluent lot was opened yesterday. Which action addresses the most likely cause?

Accepted Answer

Flush the aperture and repeat the check — A raised background usually means particulate debris or protein residue on or near the aperture, generating counts from nothing but diluent. The prescribed remedy is the instrument's flush or clean cycle, followed by a repeat background count. If the count falls within limits the analyser may be released for patient work; if it does not, escalate before any specimen is tested.

Question 3

After a leaking wash block on a cell counter was replaced, the supervisor wants proof that sample is no longer being carried from one aspiration into the next. Which procedure demonstrates that carryover is back within the manufacturer's acceptable limit?

Accepted Answer

Assay a high, then a low, sample in triplicate — A carryover study runs a specimen with a very high count three times, then immediately a very low specimen three times. Contamination shows as the first low reading sitting above the third, and the percentage is calculated from that difference against the high result. The other procedures measure precision, linearity and comparability, none of which detect transfer between aspirations.

Question 4

The chart shows a linearity study on an analyser's platelet channel: recovered values track the assigned values closely up to roughly 800 ×10⁹/L and then flatten out. A specimen from a patient with a myeloproliferative disorder returns a platelet count of 940 ×10⁹/L with no instrument flag. What is the appropriate response?

Accepted Answer

Dilute the specimen, reassay, and correct for it — The study shows the channel loses linearity beyond about 800 ×10⁹/L, so a raw result above that point understates the true count even though nothing is flagged. Diluting the specimen brings it into the verified reportable range; the recovered value is then multiplied by the dilution factor. The dilution used must be recorded with the result.

Question 5

Images are being captured from a Wright-stained film so a haematologist at another site can review the neutrophil granularity. On the monitor the first captures look distinctly bluish and the cell outlines are soft. Which adjustment should be made before the frames are saved?

Accepted Answer

Set white balance on a blank field and refocus — A colour cast comes from the camera interpreting the light source incorrectly, and it is corrected by setting white balance on an empty, illuminated part of the slide before capture. Soft outlines mean the camera's focal plane does not match the eyepiece plane, so refocusing through the live image is needed. Both must be fixed at capture, since neither is reliably recoverable afterwards.

Question 6

A set of marrow aspirate images captured during a morning run is being filed so that it can be pulled up months later if the case is reviewed. Which practice keeps the image set usable as part of the permanent record?

Accepted Answer

Link every frame to its accession number — An image is only evidence if it can be traced to the specimen it came from, so each frame must carry the accession identifier and the capture date and be filed against that record. Retrieval months later depends on that link rather than on a file name or a folder someone remembers. Storage also needs to follow the laboratory's retention and privacy rules.

Equipment and Resources

Running, calibrating and maintaining haematology instruments

Spotting instrument faults and working through them methodically

Capturing digital images of films and marrow preparations