Standard operating procedure reduces interoperator variation and improves accuracy when measuring packed cell volume

To evaluate whether a standard operating procedure (SOP) for canine packed cell volume (PCV) measurement reduces operator-dependent variation and improves accuracy within a veterinary teaching hospital environment.

Clinical staff and final-year undergraduate veterinary students were recruited to perform PCV measurements in blinded duplicate samples. Participants were randomly allocated to perform this with or without an SOP. Participants' results were compared against a reference, generated by the authors following the World Health Organization guidelines.

The study population comprised 18 clinical staff and 39 students. Three clinical staff and seven students displayed errors consistent with inaccurate reading, only one of whom had access to the SOP. Five students and two clinical staff had errors attributable to incorrect preparation, with only one having access to the SOP. Interoperator variation was significantly less using the SOP. Using the SOP, 95 per cent of the results were within 0.0125 l/l of the reference value, in comparison with within 0.09 l/l without SOP. Interoperator variation was significantly less in the SOP group (P=0.0025).

Using the SOP resulted in less variation and more accurate results. This confirms that PCV measurement with an SOP can truly be a 'waived' test.