Guided cases: spurious and true low platelet counts

This case was collected in K2-EDTA at 09:18 and analyzed at 10:02 on an impedance platelet channel. Platelets are 34 × 10^9/L with platelet-clump and abnormal-distribution flags. Mean platelet volume is suppressed or not reported, and the histogram remains elevated at its high-volume boundary rather than returning cleanly to baseline. There is no visible clot in the tube. That boundary finding is nonspecific and cannot identify clumping without the smear.

The well-made smear has numerous platelet aggregates at the feathered and lateral edges. It has no fibrin strands and no schistocyte predominance. The aggregates make the 34 × 10^9/L result analytically unreliable; the instrument result cannot determine how many platelets are contained in aggregates or how much they changed the count. It is not reportable as a reliable platelet count.

At 10:25, a fresh EDTA specimen and properly filled alternate-anticoagulant specimen are collected under the local pseudothrombocytopenia procedure. The fresh EDTA smear again has edge clumps, while the alternate-tube smear has no clumps and the locally validated method returns 178 × 10^9/L. Release only the alternate result and comment authorized by that procedure, document EDTA-associated clumping, and do not transmit a verified critical call from the unreliable 34. In a clumped EDTA specimen, a confirmed alternate result can be released only when the local validated procedure authorizes it.

As a contrast case, a separate acceptable EDTA specimen has platelets of 42 × 10^9/L, no platelet-clump flag, and a histogram that returns cleanly at both boundaries. Its well-made smear shows reduced, evenly distributed individual platelets with no aggregates, fibrin, satellitism, RBC-fragment predominance, or dominant giant-platelet population. A locally validated optical result is concordant at 44 × 10^9/L. This evidence supports release of a verified true thrombocytopenic result and any urgent communication required by local policy; document the method and communication. It still does not establish the clinical cause.