The Role of Follicular Flushing at Oocyte Retrieval

In vitro fertilization (IVF) is the most common method of medically assisted reproduction, involving fertilization of the egg by sperm in a lab. The process includes ovarian stimulation, oocyte retrieval, fertilization and culture, and embryo transfer. The success of IVF depends mainly on female age-as age increases, ovarian reserve and oocyte quality decrease-and the number of oocytes retrieved.

This study investigates whether follicular flushing during oocyte retrieval can increase the number of mature oocytes retrieved. This randomized study will be conducted in women undergoing ovarian stimulation with recombinant Folicullar Stimulating Hormone (FSH) and Gonadotropin-Releasing Hormone (GnRH) antagonist or Progestin Primed Ovarian Stimulation (PPOS) to suppress premature Luteinizing hormone (LH) rise. Final oocyte maturation will be triggered with recombinant Human chorionic gonadotropin (hCG) or GnRH agonist.

Eligible participants will have at least one follicle ≥11 mm in each ovary. On the day of oocyte retrieval, one ovary will be randomized to undergo follicular flushing using a single-lumen needle and the other simple aspiration, using the same needle. All fertilized oocytes from both ovaries will be cultured, seperately, to the blastocyst stage.

Study outcomes are the number of oocytes and mature oocytes retrieved, the oocyte retrieval rate, the mature oocyte retrieval rate, the maturation rate, the number of fertilized oocytes, the fertilisation rate, the number of blastocytes and the blastulation rate.

Sample size of 75 patients (25 per response category: poor, normal, high) provides 82-98% power to detect clinically meaningful interaction effects (Cohen's f=0.19-0.34) between response category and technique (follicular flushing vs. simple aspiration) under conservative assumptions of 50-70% of pilot study effects, lower correlations (ρ=0.35), and increased variability (α=0.05, two-sided, 5% attrition buffer.