Working the case: the designated cell-count tube

After the allocation decision, the tube designated for the cell-count bench contains 0.5 mL. It is gently inverted per procedure, immediately charged into a Fuchs-Rosenthal chamber, and read on both sides without delay. Side A reads 7 cells/uL equivalent and side B reads 7 cells/uL equivalent after the local chamber-specific formula is applied, so the two sides agree within the laboratory's defined limit and no recount is needed.

The laboratory reports the designated tube as 7 cells/uL total nucleated cells and 1,200 cells/uL RBC. It is described as slightly pink, with no clot seen. Because the two sides agree and the specimen shows no clot, this result is released as observed, with the collection and examination times documented alongside it.

For comparison, the first-drawn tube in the same collection is grossly blood-tinged and shows 18,000 cells/uL RBC and 14 cells/uL total nucleated cells, also with no clot seen. Both tubes come from the same needle pass and the same patient at the same time; only the position in the collection sequence differs.

A decreasing RBC count across sequential tubes can support the idea that blood entered the CSF space procedurally during needle placement and cleared as collection continued, but it does not prove that cause on its own; a genuine subarachnoid hemorrhage can also show tube-to-tube variation. The laboratory reports the observed, tube-specific RBC and total nucleated cell results for each tube along with tube identity and timing. It does not calculate or report a corrected white cell count for either tube.

Report what was counted, from which tube, at what time, and let the ordering clinician interpret the trend; do not turn an observed decline into a stated conclusion about its cause.