Presence of sperm in the perivitelline space predicts fertilization rate after partial zona dissection

J. Levron, D. W. Stein, J. M. Brandes, J. Itskovitz-Eldor*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Objective: To examine the association of the number of spermatozoa present in the perivitelline space and sperm parameters with fertilization after partial zona dissection in male factor patients. Design: Partial zona dissection was applied in 62 couples (84 cycles). A total of 524 oocytes underwent partial zona dissection (1/8 of the zona circumference) (partial zona dissection group) and 171 sibling oocytes were not manipulated (control group). A total of 326 manipulated oocytes were examined for the presence of spermatozoa in the perivitelline space. Setting: University-based in vitro fertilization (IVF) program. Patients: Fifty-four (87%) couples had at least one complete failure of fertilization, and 8 (13%) couples had low fertilization rate (<10%) in previous routine IVF attempts. Main Outcome Measures: Fertilization rate, cleavage rate, and the number of spermatozoa present in the perivitelline space after partial zona dissection. Results: Monospermic and polyspermic fertilization rates were 22.3% and 6.7% in the partial zona dissection oocytes and 8.8% and 0.6% in the nonmanipulated oocytes, respectively. The cleavage rate was similar in the partial zona dissection and control group (69.2% and 66.6%, respectively). A total of 81 partial zona dissection embryos and 10 nonmanipulated embryos were transferred to the uterus of 34 women (39 cycles), resulting in four pregnancies. In 46% (18 of 39) of the patients who had both partial zona dissection and control oocytes, only the manipulated oocytes fertilized. In only 48.8% of partial zona dissection oocytes, spermatozoa were detected in the perivitelline space; in this group of oocytes the fertilization rate was 56.6%. Sperm count and morphology were not clearly correlated with the outcome of partial zona dissection. Conclusions: The partial zona dissection technique enhances fertilization of subfertile sperm. However, the low efficiency of the procedure, apart from being associated with a high polyspermic rate, is related to the failure of sperm to traverse the slit in the zona pellucida in approximately one half of the manipulated oocytes.

Original languageEnglish
Pages (from-to)820-825
Number of pages6
JournalFertility and Sterility
Issue number4
StatePublished - 1993
Externally publishedYes


  • Partial zona dissection
  • in vitro fertilization
  • micromanipulation
  • oocyte
  • sperm


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