Comparison of clinical characteristics between early and late patterns in hospitalized patients with ovarian hyperstimulation syndrome

Objective To clarify the differences in clinical characteristics between early and late ovarian hyperstimulation syndrome (OHSS). Design Retrospective study. Setting Tertiary university hospital. Patient(s) Ninety-four patients/cycles hospitalized for moderate-to-severe OHSS after controlled ovarian hyperstimulation (COH) for IVF/intracytoplasmic sperm injection (ICSI); early type (n = 69) and late type (n = 25). Intervention(s) None. Main Outcome Measure(s) The COH and pregnancy outcomes, preclinical and clinical miscarriage rate, and hospital courses. Result(s) Serum E2 levels (4,955.5 ± 3,268.5 pg/mL vs. 2,340.8 ± 960.6 pg/mL) and the number of follicles ≥11 mm on day of hCG administration (15.9 ± 6.0 vs. 13.0 ± 4.0), and the number of oocytes retrieved (21.9 ± 9.7 vs. 13.2 ± 5.9) were significantly higher in the early OHSS group compared with the late OHSS group. Clinical pregnancy rate (PR) was significantly higher in the late OHSS group (23.6% [13/55] vs. 92.0% [23/25]). There were no significant differences in multiple PR and disease severity between the two groups. Conclusion(s) Early OHSS is associated with excessive ovarian response to gonadotropin stimulation, whereas late OHSS is closely associated with conception cycle. Our findings do not support that late OHSS is more severe and closely associated with multiple pregnancies compared with early OHSS.