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Quality and Risk Management in the IVF Laboratory
significant change necessitated recalculation of the control values, using the August 1997 to January 1998 monthly average values, as shown in chart B. The increased value for the control mean indicates a systematic improvement in zygote grade while the narrower control limits express the improved stability (i.e. reproducibility) of the new culture system. A further example, shown in Figure 6.5, illustrates the use of control charts to investigate whether the major reconstruction of an IVF lab had any detrimental impact upon the Indicators used to monitor the lab’s performance. Since the Indicators during the periods preceding and after the renovations all remained within the previously-established control limits, the Lab Director was able to state with confidence that the renovations had not had any detrimental effect on fertilization rate or embryo quality (Mortimer et al., 2001a). Previously we have termed the sort of Indicators that are being considered here as “Laboratory Performance Measures” or LPMs (Mortimer, 1999; Mortimer et al., 2001a), but have more recently harmonized the term as “Laboratory Performance Indicators” or LPIs. Naturally there are other Indicators that can be used to monitor aspects of clinical performance or even of the overall program where the endpoint of interest depends on other sources of variability rather
Figure 6.5
Control charts displaying monthly averages for three aspects of laboratory performance before and after a period of major laboratory renovation. Data from Mortimer et al. (2001a), see text for explanation.