Early and late presentation of the ovarian hyperstimulation syndrome: two distinct entities with different risk factors

This study was designed to identify clinical predictors forearly and late ovarian hyperstimulation syndrome (OHSS). A retrospectiveanalysis of all 592 in-vitro fertilization (IVF) cycles fromthe programme's inception in 1988 up to March 1993 was performed.Six patients (1.0° of cycles) had moderate or severe OHSSpresenting 3–7 days post-human chorionic gonadotrophin(HCG), and four patients (0.7° of cycles) had severe OHSSpresenting 12–17 days post-HCG. No patient with earlyOHSS went on to develop late OHSS, and no patient with lateOHSS had demonstrated early OHSS. Stepwise logistic regressionshowed that early OHSS was predicted by the number of oocytesretrieved (range 18–46) (P= 0.0001) and the oestradiolconcentration on the day HCG was given (range 12 122–24454 pmol/1) (P = 0.0003). Late OHSS was predicted by the numberof gestational sacs (range 2–3) on ultrasound 4 weeksafter embryo transfer (P = 0.0001) but not by the number ofoocytes or oestradiol. Early OHSS was an acute effect of theHCG administered prior to egg retrieval in women with high oestradioland larger numbers of follicles (range 22–51). Late OHSSwas induced by the rising serum concentration of HCG producedby the early pregnancy, and in this series of cases it was associatedonly with multiple gestation.