The objective of this prospective study was to examine the ability of the hemizona assay (HZA) to predict fertilization outcome of mature, pre-ovulatory oocytes under in-vitro fertilization (IVF) conditions. Since a large number of patients were evaluated over a long period, the power of the HZA to prognosticate fertilization results in the same and subsequent (consecutive) IVF cycles of those same patients was assessed. For IVF, only metaphase II oocytes were used. For the HZA, both fresh oocytes donated by patients at the time of IVF and oocytes recovered from surgically removed ovarian tissue (and salt-stored) were used, and bisected by micromanipulation techniques. Matching hemizonae were co-incubated either with spermatozoa from the patient (test) or from a fertile man (control) for 4 h. The number of spermatozoa tightly bound to the zona was counted. Patients (n = 112) were divided into two groups based on HZA results (expressed as HZA index or HZI): HZI greater-than-or-equal-to 30% (n = 72) and <30% (n = 40). The patients with HZI <30% had significantly lower fertilization rates in both the HZA - IVF cycle and in subsequent cycles compared to patients with HZI greater-than-or-equal-to 30% (P < 0.03). Linear discriminant analysis indicated the HZA to have a sensitivity of 84%, and positive and negative predictive values of 85 and 70% respectively, for prediction of fertilization outcome in a total of 233 cycles. It was concluded that the HZA is a good predictor of fertilization rate in vitro, and can be used in the IVF setting to supply additional clinical information in male-factor patients.
