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

OBJECTIVES

To analyse the incidence and factors associated with the ovarian hyperstimulation 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 micrograms) 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%, P < 0.05) who had their embryos cryopreserved developed severe OHS compared with women with an E2 > 3500 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.