Hemizona index (HZI) demonstrates excellent predictability when evaluating sperm fertilizing capacity in in vitro fertilization patients.

The objective of this work was to assess the power of the hemizona assay to predict in vitro fertilization (IVF) results using receiving operating characteristics (ROC) analysis. In a tertiary medical center setting, 94 couples undergoing IVF were included in the study comparing their fertilization results to sperm function during the hemizona assay. Using ROC analysis, fertilization in IVF (mature oocytes only) was compared to performance of the sperm in the sperm-zona pellucida binding test as expressed by hemizona index (HZI; [number of test sperm bound/number of control sperm bound] x 100). The IVF results were as follows: 32 patients had no fertilization (0%), 55 patients fertilized all of the oocytes (100%), and 7 patients fertilized between 14% and 85% of the oocytes. Modified ROC analysis was used to determine the best threshold for fertilization success or failure, depending upon how the data are viewed. A HZI of 40-43 separated the 100% fertilization group from the other groups, with a true positive rate of 87% and a true negative of 83%. Conversely, a HZI of 4-5 separated the 0% fertilization versus partial or total fertilization, with a true positive rate of 100% and true negative rate of 71%. Sperm performance in the hemizona assay as measured by the HZI reflects performance in IVF and benefits couple evaluation and counseling.