Low numbers of oocytes retrieved for assisted reproduction correlate with higher failure rates, yet no published guidelines address retrieval techniques.
Elizabeth S. Ginsburg, MD, fellowship director in the Center for Infertility and Reproductive Surgery at Brigham and Women’s Hospital, Catherine E. Gordon, MD, a former fellow in the Division, and colleagues surveyed physicians at the Brigham about their techniques and compared oocyte retrieval outcomes. In the Journal of Assisted Reproduction and Genetics, the team says no clear top-performing technique was evident, even for patients with few follicles.
Nine attending physicians completed a survey about their oocyte retrieval techniques. All retrievals were performed under anesthesia with a 17-gauge needle at a pressure of 90 to 100 mm Hg.
Data were collected for all completed autologous in vitro fertilization and intracytoplasmic sperm injection cycles for which retrieval was performed between March 1, 2013, and July 30, 2019. Three outcomes were analyzed, stratified by the number of follicles imaged by ultrasound on the day of trigger (<6, 6–10, or >10):
- Number of mature oocytes per total number of oocytes retrieved (primary outcome)
- Number of oocytes per number of follicles measuring ≥12 mm
- Number of mature oocytes per number of follicles
The technique with the highest outcome ratio was termed the top-performing technique (TPT).
Each physician had different survey responses, so nine individual techniques were considered. The key findings were the following:
- There was no consistent TPT across follicle number groups or across outcomes within any of the follicle number groups
- The parameters most commonly associated with a TPT were re-sticking and curetting follicles (independently)
- Most TPTs involved holding the probe coronal or variable as opposed to sagittal
- A higher ratio of oocytes per follicle did not consistently result in a higher ratio of mature oocytes per follicle, and neither outcome was associated with a higher maturation rate
The survey responses did suggest some principles to follow:
- When <6 follicles are present on ultrasound on the day of trigger, re-sticking previously entered “old” follicles is important for optimizing the oocyte/follicle ratio
- When ≥6 follicles are present, reversing the probe to retrieve the opposite side may be helpful
- Using a low-pressure system is crucial to avoid the destruction of the cumulus–oocyte complex
- Suction should be applied once the needle is in the ovary, before entering the follicle to avoid follicular fluid loss, and suction should be released when pulling the needle out of the ovary and vagina to avoid pressure spikes within the needle and tubing, which can cause shear stress force on the oocyte
- None of the surveyed physicians reported flushing follicles; studies have shown this has no impact on oocyte yield