Does the 18‐h sperm motility influence intrauterine insemination results?

This is the authors' abstract. We don't add key points for this paper.

Dear Editor Sperm quality has a major influence on the results of intrauterine inseminations (IUI), especially through the number of motile spermatozoa recovered after preparation and their morphology (Wainer et al., 2004). Another sperm parameter reported to impact IUI results was sperm motility after 18 h or 24 h incubation (so-called sperm survival by approximation) in culture media after preparation with a drop in pregnancy rate from 21% if survival is >70% to less than 4% when it is ≤70% (Branigan et al., 1999). However, there is no recent data on this subject and in their systematic review on the effect of semen quality on IUI results, Ombelet et al. have found no other paper on sperm survival since the one of Branigan et al. published in 1999 (Ombelet et al., 2014). Therefore, we aimed to revisit the concept of a deleterious impact of low sperm survival on IUI outcome. The study included 1793 consecutive IUI performed in 713 couples at the Toulouse university hospital from January 1, 2012 to December 31, 2016. Ovarian stimulation used a combination of recombinant FSH and GnRH antagonist. Ovulation was induced by injection of recombinant hCG when at least one follicle ≥18 mm was obtained. Insemination was performed 36 h after hCG injection. Clinical pregnancies were defined as the presence of a fetal heartbeat seven weeks after insemination. Semen analysis was performed within six months before the first IUI. After conventional analysis (volume, concentration, and motility), spermatozoa were prepared according to WHO 2010 using discontinuous density gradient centrifugation (three layers: 60%, 80%, 90%) (Puresperm®, Nidacon, Mölndal, Sweden). After preparation, spermatozoa were incubated in 400 μL universal IVF medium (Origio, Versailles, France) at 37 °C in a 6% CO2 atmosphere. Motility was assessed after a 18 h incubation. Sperm preparation on the day of IUI was performed in the same way. The clinical pregnancy rate per attempt was not different according to the 18 h motility classes (defined by centiles) (13.4% for motility <25%, 15.5% for 25% < motility < 45%, 12.1% for 45% < motility < 60%, 15.0% for 60% < motility < 70%, 15.3% for 70% < motility < 80%, and 16.5% for motility ≥ 80%; NS). This finding is opposite to the results published by Branigan et al., who reported a pregnancy rate per cycle lower than 4% when the motility after a 24 h incubation was lower than 70%. However, the proportion of low survival rate (<20%) is much lower in our study (<10%) than in their study (Table 1) (36%) although they adjusted sperm concentration to a maximum of 10 millions motile sperm per milliliter for evaluating sperm survival which should have help maintain it. This difference could reflect discrepancies in the treated population and/or in techniques. Indeed, in the 20 years between the two studies, numerous modifications have been carried out concerning gradient as well as media. It must be pointed out that in the Branigan et al. study the semen analysis was performed in the 2 or 6 weeks before IUI, while in our study up to 6 months separated semen analysis and IUI. However, the semen characteristics at the time of IUI and during analysis before are closely linked (number of motile spermatozoa; r = 0.688; p < 0.0001). Discrepancies between the studies, as for instance the pregnancy rate per cycle when the number of recovered spermatozoa is lower than 5 × 106 (0/33 in the Braginan's study vs. 80/607 in our; p < 0.05), could be explained by non-spermatic parameters. For example, the ovarian stimulation protocols vary from one study to another, especially with the use of GnRH antagonists which have been reported to have a huge impact on IUI results (Luo et al., 2014). Indeed, GnRH antagonists allow to have multi-follicular recruitment as well as a better synchronization between ovulation and insemination, which could be crucial in case of sperm deficiency (Monraisin et al., 2016). In conclusion, the 18 h sperm survival does not seem to have a screening value for indication of IUI.