Effects of cryopreservation time and thawing method of human oocyte vitrification on the outcome of assisted reproduction / 中华妇产科杂志

ABSTRACT

Objective To evaluate the effects on pregnancy outcome of freezing time from oocyte retrieval and thawing method for metaphase Ⅱ human oocytes vitrification. Methods From Mar 2007 to Mar 2009, the clinical outcome of 30 infertile women undergoing vitrified-thawing oocytes of in vitro fertilizationembryo transfer(IVF-ET) in the Reproductive Medical Center of the First Affiliated Hospital of Zhengzhou University was studied retrospectively, including 21 women with double fallopian tube obstruction and 9 women's husband azoospermia. All infertile women were divided into three groups, including 5 cases in group A (freezing between 4 and 5 hours from oocyte retrieval and conventional thawing method), 9 cases in group B (freezing within 2 hours from retrieval and conventional thawing method) and 16 cases in group C (freezing within 2 hours from retrieval and improved thawing method). The vitrified oocytes were preserved for 2 months to I year and thawed for Intracytoplasmic sperm injection (ICSI) and embryo transfer. The outcome of IVF and pregnancy were recorded. Results (1) The rates of oocyte survival was (65±33) % in group B and (72±23)% in group C and the rate of transfer cycle was 9/9 in group B and 16/16 in group C, which were all significantly higher than (16±17) % of oocyte survival and 1/5 of transfer cycle in group A (P = 0. 001,0. 021). However, the rate of oocyte survival and transfer cycle between group B and group C did not reach statistical difference (P > 0. 05). The rate of implantation and clinical pregnancy of (33±38) % and 9/16 in group C were significantly higher (4±11)% and 1/9 in group B (P =0. 033,0. 040).(2)The mean age of women in group C were (28.6±2.1) in oneself oocyte, (28.0±4.6) in donor oocyte and (28.1±3.4) in donor sperm. The rate of oocyte survival was (73±25) %, (88±10) % and (66±25) %. The rate of fertilization rate was (84. 6±0. 9) %, (79. 3±2. 0) % and (82. 8±15.0) %. The rate of implantation was (20. 0±44. 7) %, (33. 0±0. 1) % , (41.6±41.7) %. The rate of clinical pregnancy was 1/5 in oneself cycles,3/3 in donor oocyte cycles, 5/8 banked donor sperm cycles in group C. All above clinical parameters were not statistically different (P >0. 05). (3) In group A, one women underwent IVFET and no clinical pregnancy was observed. One women pregnancy was terminated at two months in group B.The clinical pregnancies rate of group C was 9/16, late abortion occurred in 1 woman, the other 8 women underwent term pregnancy, including 5 male infants and 4 female infants. All of infants showed normal Karyotype. Live-birth rates per warmed oocyte was 5.9% (8/135). The mean gestational weeks and birth weight of the infants were (39. 4±0. 9) weeks and (3574±569) g, respectively. Conclusions Embryo quality and clinical outcome of thawing cycles could be significantly improved when oocyte vitrification was performed within 2 hours from oocyte retrieval and improved thawing method.