Early and late ovarian hyperstimulation syndrome: early pregnancy outcome and profile

Abstract

BACKGROUND: Ovarian hyperstimulation syndrome (OHSS) in IVF/ICSI cycles may occur either as an early (early onset) or a late pattern (late onset). This observational study was designed to identify whether the onset pattern of OHSS is associated with the occurrence of pregnancy and the early pregnancy outcome. METHODS: Among 4376 consecutive IVF/ICSI cycles, 113 patients were hospitalized for OHSS after IVF/ICSI treatment and were included in the study. The setting was the Dutch-speaking Brussels Free University Hospital, between June 2000 and September 2002. RESULTS: Early OHSS occurred in 53 patients, and late OHSS complicated 60 patients. A total of 96.7% of the late OHSS cases occurred in a pregnancy cycle and were more likely to be severe than the early cases (PPP=0.02). Estradiol levels and number of follicles on the day of HCG were significantly higher in the early OHSS group. However, there was no difference in estradiol values on the day of hospital admittance between the two groups. In addition, the number of follicles on the day of HCG administration appears to be a better prognostic indicator for the occurrence of severe OHSS than the estradiol values (87% of the severe cases had ≥14 or follicles of a diameter ≥11 mm, whereas only 50% of them had an estradiol value ≥3000 ng/l). CONCLUSIONS: The early OHSS pattern is associated with exogenously administered HCG and a higher risk of preclinical miscarriage, whereas late OHSS may be closely associated with the conception cycles, especially multiple pregnancies, and is more likely to be severe. Further clarification of these two different clinical entities could have implications for research protocols as well as for preventive and management strategies for OHSS.