Table 2 Risk factors/predictive factors for OHSS (adapted from Humaidan et al [10])

Primary risk factors (patient related)

· High basal AMH

- >3.36 ng/mL independently predicts OHSS [12]

· Young age

- <33 years predicts OHSS [12]

· Previous OHSS

- Moderate and severe cases, particularly those with hospitalization

· PCO like ovaries

- >24 antral follicles in both ovaries combined

Secondary risk factors (ovarian response-related)

On day of hCG trigger

· High number of medium/large follicles

- ≥13 follicles ≥11 mm in diameter [14] - >11 follicles ≥10 mm in diameter [12]

· High or rapidly rising E2 levels and high number of follicles

- E2 5,000 ng/L and/or ≥18 follicles predictive of severe OHSS [14]

· Number of oocytes retrieved

- >11 predicts OHSS [12]

· VEGF levels

- Not applicable

· Elevated inhibin-B levels

- Elevated levels on day 5 of gonadotropin stimulation, at oocyte retrieval and 3 days before

· hCG administration for LPS

- Not applicable

· Pregnancy (increase in endogenous hCG)

- Not applicable