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Sperm morphology: assessing the agreement between the manual method (strict criteria) and the sperm morphology
T F Kruger1, T C du Toit, D R Franken
1University of Stellenbosch, Tygerberg, Republic of South Africa.
Objectives:
To correlate the percentage normal morphology reported by different observers and a computerized method (IVOS; Hamilton-Thorne Research, Beverly, MA) on a slide-by-slide basis using strict criteria: [1] Experienced observer (T.F.K.) versus experienced observer (R.M.), [2] experienced observer (T.F.K.) versus sperm morphology analyzer (IVOS), and [3] repeatability of normal and abnormal cells (IVOS). DESIGN SETTING, PATIENTS: Slides from 30 different patients from the Tygerberg IVF program were selected randomly. Microscopic fields and sperm cells were chosen randomly and percent normal morphology was recorded (objectives 1 and 2). The same slides were used and a cell-by-cell repeatability was done as outlined (objective 3).
Results:
Experiment 1 (objective 1): there was no significant bias between T.F.K. and R.M. The limits of agreement were 8.6% and -7.3%. The SDs were not significantly different (P = 0.1283). The Spearman correlation coefficient between readers was 0.83. Experiment 2 (objective 2): the same findings were reported but the limits of agreement were 12.1% and -15.5%. The Spearman correlation coefficient was 0.85. The limits of agreement was tighter below 20% normal forms (+8.4 and -6.6). Experiment 3 (objective 3) (repeatability): 255 cells were analyzed three times in succession. Estimating pairwise agreement, the kappa statistic for the pairs are 0.85, 0.80, and 0.85, respectively, which compares favorably with the second canonical moment of 0.8329 (kappa = 0.83).
Discussion:
The computer's ability to classify normal morphology per slide is promising. Below 20% normal forms, the limit of agreement is tight. Because of the 6% higher reading compared with the manual method, different thresholds possibly will be developed to identify subfertile from fertile patients. The computer gives excellent repeatability of normal and abnormal cells. Based on results obtained, this system can be of clinical value both in IVF units and andrology laboratories but more clinical data is required in this field.