Iris de Nie

40 C H A P T E R 3 and post-thaw sperm motility was classified using a three-category scheme: progressive motile, motile, and immotile. Subsequently, ejaculates were diluted 1:1 and mixed thoroughly for at least 10 minutes with medium containing glycerol or egg yolk (TYB, Irvine Scientific) as cryoprotectant and put in 0.3 or 0.5 mL vials. Vials were put upright just above liquid nitrogen for gradual crystallization in nitrogen vapor . After total crystallization straws were stored in vapor phase nitrogen tanks. After 24 to 72 hours, one vial was thawed and a semen analysis was performed, as described above. Some fertility laboratories assessed post-thaw semen quality of all semen samples, some assessed only one of the provided semen samples, and in two centers no assessment of post-thaw quality was performed. The choice of the most appropriate ART (IUI, IVF, or ICSI) is often determined by the total motile sperm count (TMSC) per vial since it reflects sperm concentration and motility, as well as the effects of sperm processing. It is difficult to establish the most optimal cut-off values for the different types of reproductive techniques since a successful treatment is also dependent on other factors, such as the woman’s fertility, and therefore, recommended thresholds vary in literature. 76,77 In this study, suitability for the most appropriate ART was determined using the following cut-off values: TMSC > 2 million is suitable for IUI, TMSC > 1 million and < 2 million is suitable for IVF, and TMSC < 1 million is suitable for ICSI. Statistical analysis Descriptive analyses were conducted to assess the distributions of semen parameters and patient characteristics, normally distributed data are presented as mean with SD, and non-normally distributed data as median with interquartile range (IQR). Qualitative data are presented as number with percentages. For trans women who preserved multiple semen samples, the collective semen parameters were averaged and the means were used for statistical analysis. 78,79 Semen quality was categorized in the following descriptive diagnoses, using reference values of the World Health Organization (WHO) for human semen: oligozoospermia (reduced sperm count), asthenozoospermia (reduced sperm motility), oligoasthenozoospermia (reduced sperm count and motility), azoospermia (no sperm in the ejaculate) or normozoospermia (normal semen parameters). 11 Post-thaw semen quality was assessed by calculating the TMSC per vial. Since volumes of vials differed between fertility laboratories a correction was performed to enable accurate comparison. Wilcoxon signed-rank tests were performed on non-normally distributed semen parameters to compare with data from the general population of unscreened men. 10 Azoospermic trans women were excluded from analysis of sperm concentration, total sperm number and percentage progressive motility. Pre-determined factors (i.e. age at time of semen cryopreservation, alcohol consumption, smoking, cannabis use, BMI, previous feminizing hormone use, a history of inguinal hernia repair or cryptorchidism, and a history of depression and anxiety) were used in logistic regression analyses to assess their impact on semen quality in our cohort. Semen parameters