Objective: To assess the impact of oocyte vitrification on aneuploidy and reproductive potential by comparing vitrified and control oocytes from a single patient within a single cycle and a single fresh transfer.
Design: Paired randomized controlled trial in which each patient's cohort of mature oocytes was divided into two even groups with half undergoing Cryotop vitrification and rapid warming and half serving as controls.
Setting: Academic center for reproductive medicine.
Patient(s): Forty-four patients with a mean age of 29.9 ± 2.3 years and normal ovarian reserve.
Intervention(s): Cryotop vitrification of half of mature oocytes. Trophectoderm biopsy with single nucleotide polymorphism microarray analysis for ploidy and DNA fingerprinting.
Main outcome measure(s): Rate of aneuploidy (primary outcome), fertilization, cleavage, blastulation, and implantation in embryos derived from vitrified and control oocytes.
Result(s): A total of 588 mature oocytes were randomized, with 240/294 (81.6%) surviving vitrification. Among surviving vitrified oocytes, there was a lower fertilization rate with intracytoplasmic sperm injection (77.9% vs. 90.5%; relative risk [RR], 0.86; 95% confidence interval [CI], 0.80-0.93), a lower cleavage rate (90.9% vs. 99.2%; RR, 0.92; 95% CI, 0.87-0.96), and a lower usable blastocyst formation rate per two pronuclei (34.8% vs. 50.8%; RR, 0.68; 95% CI, 0.54-0.86). There was no difference in the rate of embryonic aneuploidy (vitrified, 29.1% vs. control, 26.4%). In paired blastocyst transfers, the ongoing pregnancy rate per embryo transferred was similar (vitrified, 53.9% vs. control, 57.7%).
Conclusion(s): Although the IVF process is less efficient after oocyte vitrification, implantation rates are equivalent and there is no increased risk of aneuploidy. Given the lack of other viable options, this study provides great reassurance to patients and clinicians applying oocyte vitrification for fertility preservation.
Copyright © 2012. Published by Elsevier Inc.