Does elective cryopreservation of all embryos from women at risk of ovarian hyperstimulation syndrome reduce the incidence of the condition?

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Abstract
Objectives To analyse the incidence and factors associated with the ovarian hyper-stimulation syndrome (OHS) in our IVF/GIFT programme before and after the introduction of a strategy to cryopreserve all embryos from women judged to be at risk. Design Two hundred forty-one consecutive IVF/GIFT cycles from January to December 1989. Setting Specialist fertility unit, Manchester, UK. Interventions Pituitary suppression was effected by a daily subcutaneous injection of buserelin (500 μg) beginning 7 days before the expected menses. The ovarian stimulation was with variable amounts of human menopausal gonadotrophin. Ovulation was induced with 10 000 i.u. human chorionic gonadotrophin (hCG). From January to May (period A), gametes/embryos were replaced and 2000 i.u. hCG given, irrespective of the serum oestradiol (E2) concentration. From June to December (period B), all the embryos from women with an E2>3500 pg/ml on the day of ovulatory trigger were electively cryopreserved. Main outcome measures Serum E2, features of moderate or severe OHS, clinical pregnancies. Results The OHS occurred in 10/105 (9.5%) and 12/136 (8.8%) cycles in periods A and B, respectively. Fewer women (6% versus 60%, P3500 pg/ml who became pregnant after gamete/embryo transfer in period A. The main factors associated with the development of OHS were serum E2 concentrations >3500 pg/ml, whether gamete/embryos were replaced and the additional hCG given, the occurrence of a pregnancy and the presence of polycystic ovary disease. Conclusion The elective cryopreservation of all embryos from women with high E2 levels reduced the severity, but not the incidence of symptomatic OHS.
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