IVF/ICSI cycles with GnRH antagonist protocol: is it possible to avoid weekend oocyte retrievals?

Overview and Aims: Ovarian stimulation with gonadotrophins and LH surge suppression with GnRH antagonist has become the most widely protocol used in IVF/ICSI cycles. The main disadvantage lies in the lack of flexibility on the starting day of gonadotrophin stimulation when a fresh transfer is planned, which may lead to a higher frequency of weekend retrievals. The aim of this study was to determine the best weekday to start gonadotrophin stimulation to reduce the frequency of weekend oocyte retrievals in IVF/ICSI cycles using GnRH antagonist protocol, as well as to evaluate the impact of the day of oocyte retrieval in laboratory parameters. Methods: A retrospective cohort study was performed in the Reproductive Medicine Unit of a Portuguese University Hospital. The study included all consecutive women undergoing oocyte retrieval between January-2016 and December-2021 after gonadotrophin stimulation with GnRH antagonist protocol with an intent of fresh embryo transfer. The main outcome was to determine which weekday for initiating ovarian stimulation led to the lowest number of weekend retrievals. Secondary outcomes included assessing whether the laboratory results were affected by the day of retrieval. Results: A total of 376 IVF/ICSI cycles were analyzed. Most oocyte retrievals were performed during the 5-day workweek, with 45 (12%) occurring during the weekend. Saturday and Sunday oocyte retrievals were less likely when gonadotrophin stimulation started on Friday (p=0.01) and more likely when started on Monday (p=0.002) or Tuesday (p=0.008). The number of oocytes retrieved per cycle and viable day 2 embryos were not influenced by the day of retrieval and, even though fertilization (66% vs. 71.6%) was lower in the weekend group, the difference was not statistically significant. Conclusions: The onset of ovarian stimulation on Monday or Tuesday resulted in significantly more oocyte retrievals during the weekend. Regarding laboratory outcomes, no difference was found between the cycles with or without weekend retrievals.