Objective: To assess partial zona dissection in our routine IVF-ET program over a 2-year period.
Design: Partial zona dissection before insemination on the day of oocyte collection or 24 hours after unsuccessful conventional IVF. In a subgroup of patients, oocytes were randomized to either partial zona dissection before insemination or IVF.
Setting: University infertility clinic.
Patients: Couples who suffered principally from male factor infertility or who had failed fertilization previously.
Interventions: Micromanipulation of oocytes with partial zona dissection.
Main outcome measures: Comparison of fertilization rate, embryo morphology, and implantation rate between partial zona dissection inseminated oocytes and conventional IVF inseminated oocytes (controls).
Results: Five pregnancies were established in 199 patients. The incidence of polyspermy was significantly higher in the partial zona dissection group than in conventional IVF (4.8% versus 1.3%). There were no significant differences in the remaining parameters. The fertilization rate of partial zona dissection and reinsemination was significantly higher than conventional IVF insemination (13.6% versus 4.5%) but similar to the rate obtained when partial zona dissection was applied before insemination (13.6% versus 15.7%).
Conclusions: Oocytes treated by partial zona dissection did not exhibit a greater fertilization rate than conventional IVF inseminated oocytes. Partial zona dissection may not be a useful technique for treating severe male factor infertility.