Comparison of two staining and evaluation methods used for computerized human sperm morphology evaluations
The purpose of the study was to analyse the agreement between computer analysed (Hamilton Thorne, IVOS Dimensions Version 3) normal sperm morphology and values obtained from 97 slides stained according to the Papanicolaou and Diff-Quik method. Liquefied semen samples were washed once by centrifugation and air dried smears on slides were made, which were stained according to the Papanicolaou and Diff-Quix method and analysed by computer. The paired t-test was used to assess whether any bias existed between the two methods. The limits of agreement were calculated using the Bland and Altman approach and a modification of this approach (mean-dependent limits). A significant bias of 1.6% was obtained in favour of higher normal sperm morphology percentages when using the Diff-Quik method. The standard limits of agreement were -13.4% to 16.6%, whereas the mean-dependent limits of agreement were 1.6% [5.8 + 0.6 (mean percentage normal morphology)]. Statistically, the Diff-Quik and Papanicolaou staining methods produce different normal sperm morphology profiles. These inherent differences may, therefore, require the establishment of new normal sperm morphology thresholds for male fertility, based on clinical data, when using the Diff-Quik staining method in conjunction with computerized analysis.