Unstimulated immature oocyte retrieval: Early versus midfollicular endometrial priming

Objective: To assess the ability to retrieve transvaginally unstimulated immature oocytes from assisted reproductive technology (ART) patients and to determine their competency to mature, fertilize, and implant with early versus midfollicular exogenous estrogen endometrial priming. Design: Prospective randomized study. Setting: In vitro fertilization unit, private reproductive endocrinology and infertility practice. Patient(s): Fourteen patients, all had failed at least one IVF cycle. Intervention(s): Early follicular endometrial priming was initiated on cycle day 3 with 2 mg 17 beta-E(2) twice per day (group A). Midfollicular endometrial priming was initiated with 1 to 2 mg/d of 17 beta-E(2) between cycle days 5 and 7 and gradually increased by 1 to 2 mg/d until the oocyte retrieval (group B). The oocytes were allowed to mature in 0.075 IU FSH or hMG, 0.5 IU of hCG, 1 mu g of 17 beta-E(2) in Eagle's or Tissue Culture Media 199, fertilized, and transferred 72 hours later. Main Outcome Measure(s): Maturation, fertilization, and pregnancy rate. Result(s): Group A patients had 83 oocytes retrieved (11.8 +/- 6.1) versus 78 oocytes (11.1 +/- 2.7) from group B. The maturation rate in group A was 39.7% (34/83) versus 61.5% (48/78) in group B. The fertilization rate was 75.7% (25/34) in group A versus 75.0% (36/48) in group B. The cleavage arrest rate was significantly higher, 36.0% (9/25) in group A versus 8.3% (3/36) in group B. The number of embryos transferred was 1.8 embryos per retrieval in group A versus 4.0 embryos per retrieval in group B. One pregnancy was established in a patient with tubal disease in group B who delivered at 36 weeks gestation. Conclusion(s): Unstimulated immature oocyte retrieval can be performed successfully in ART patients. Midfollicular endometrial priming was able to achieve successful maturation (60%), fertilization (75%), and cleavage (92%), with the delivery of a successful pregnancy. (C) 1997 by American Society for Reproductive Medicine.