Oocyte vitrification: reproductive outcome in patients with low number of oocytes

Abstract

OBJECTIVE: Recent advances in oocyte cryopreservation have been reported by the use of vitrification. Since 2005, this technique has shown very good results. The aim of this trial is to report reproductive outcomes with oocyte vitrification technique in patients with low number of oocytes. DESIGN: Retrospective study carried out between January 2008 and December 2009 in a private IVF clinic. MATERIALS AND METHODS: 184 methaphase II oocytes corresponding to 36 patients were vitrified using Cryotop method. Less than 8 oocytes were obtained from each patient (mean: 5,2 ± 2,3SD). After oocytes were thawed, the ones which survived were inseminated by ICSI procedure. RESULTS: 163 oocytes (88.6%) survived after warming (mean:4,7 ± 2,2 SD). 116 oocytes fertilized after ICSI procedure (71.1%), cleavage rate was 89,6% (104/116). A total of 88 embryos were transferred on day 3 (mean 2,5 ± 1,5 SD). Of the total embryos transferred, 51% (53/104) were excellent/very good quality, and 49% (51/104) were regular quality. Clinical pregnancy rate was 33.3% (12/36). One twin and one triplet pregnancy occurred. Implantation rate was 17% (15/88) and abortion rate was 16,7% (2/12). At the time of this report, 2 healthy babies were born and 10 pregnancies are still ongoing. CONCLUSION: Our study revealed a high survival and fertilization rates after oocyte warming. These parameters resulted in a high number of good quality embryos. Clinical pregnancy rate was also acceptable. This report supports introducing vitrification as a new method even when low number of oocytes are retrieved.