Surreptitious pipetting errors on a vendor-programmed liquid handler.

Liquid handlers (LHs) have become common in both clinical and academic laboratories for the preparation and manipulation of samples. In theory, these systems offer the potential for reduced error due to the elimination of mis-pipetting errors. In reality, these systems still have potential for mis-pipetting and require careful validation by the end user. In this case report, we describe two instances where inappropriate pipetting by a vendor-programmed LH were observed. In each case, the worklist that was obtained from the LH failed to reflect what had actually been pipetted and as such these instances represented significant near misses with substantial potential for patient harm. Neither of these instances were caught during the laboratory's validation studies of the LH. Laboratories should be aware of the potential for mis-pipetting by LHs. LH vendors should work to ensure the worklists reflect what was pipetted (instead of what was intended to be pipetted) and end users must ensure robust validation studies that take into account as many "real world" scenarios as possible.