When an Aliquot Does Not Balance
Part of Clinical Laboratory (LAB) Training: Aliquoting, Labeling and Chain of Custody.
About 2 minutes. Free, in your language, no account needed.
The count is wrong, and that is information
You made four and the log says five. Or the box holds seven and the manifest says eight.
Something specific happened. Finding out what is more useful than adjusting the number.
Do not correct the log to match the shelf
The instinct is to make the record agree with reality. That destroys the discrepancy, which was the only evidence that something occurred.
Record both: what the log said and what you found. Then investigate.
The likely explanations, roughly in order
A miscount, at either end. Recount before anything else.
An aliquot was never made, because volume ran out and it was not recorded.
It is in a different box, misfiled at storage.
It was used, for a quality check or a repeat, and not logged.
It was discarded, as a breakage or a spill, without a record.
Most turn out to be the first three.
Check the parent
If the parent tube is still available, the volume remaining tells you a lot. A parent with more left than expected suggests an aliquot was never made rather than lost.
Write the investigation down as you go
Who you asked, what they said, what you checked and what you found. Even when the answer turns out to be a miscount.
An investigation with no record reads, later, like nothing was done.
Report it even when it resolves
A resolved discrepancy is still a discrepancy. The sponsor needs to know the sample exists and where it was, especially if it supports an endpoint.
Reporting a problem you already solved is how a laboratory builds the credibility that matters when you report one you have not solved.
If it cannot be found
Say so plainly, with what you checked. An honest missing-sample report lets the sponsor assess the endpoint impact and decide whether a repeat draw is possible.
A sample quietly written off is a data point that disappears without anyone able to explain it.