February 8 2011 (Tuesday) - Q.C.
(Apologies for rather iffy photograph…)
When checking QC it's not enough that the spots on the plot are the right colour. One needs to be sure that results aren't all bouncing at the high or low limits. Also one needs to look out for trends. In this case it is clear that the QC results, whist still perfectly acceptable, are noticeable going off as the red cell count slowly climbs. And as the red cell count climbs, so all associated parameters are slowly deteriorating too.
Replacement of an O-ring brought all results back to the expected mean before a QC failure occurred.