INTRACYTOPLASMIC SINGLE SPERM INJECTION - PRECLINICAL TRAINING AND FIRST CLINICAL-RESULTS

Objective: Our purpose was to reduce oocyte damage before clinical application of intracytoplasmic single sperm injection by training on aged unfertilized oocytes. Design: Intracytoplasmic single sperm injection (ICSI) was accomplished by micromanipulation of sperm and oocytes. Patients: Thirty-four patients consented to donate unfertilized aged oocytes to train for ICSI. Forty-four patients suffering from severe male infertility were treated with ICSI. Intervention: Oocytes were inseminated by intracytoplasmic single sperm injection. Main Outcome Measures: Oocyte damage and fertilization and pregnancy rates were the outcome measures. Results: One hundred fifty-one aged unfertilized oocytes were gathered for training of which 121 were injected with a single sperm and 30 without a spermatozoon as a control group for activation. Oocyte damage, initially as high as 40%, was reduced to 15% after 60 oocytes. Normal fertilization (2PN) occurred in 18%, and polyploidy in 4.4%. The cleavage rate was 69%; none of these embryos were transferred. In the control group, seven oocytes were damaged, seven (30%) shelved one pronucleus, and one showed two pronuclei. No cleavage was observed in the control group. In the clinical trial, 44 patients (61 cycles) were clinically treated with the same ICSI procedure, including 575 of 721 collected oocytes. Damage was 13%, activation was 11%, normal fertilization was 30%, and 5 (1%) polypoid zygotes were observed. The fertilization rate ranged from 5 to 100;, with a mean of 39.5 +/- 4% (SE). Nine patients had no fertilization (15%). Ninety-six percent of the zygotes cleaved and 47% were at the four-cell stage 45 hr after injection. One hundred twelve embryos were replaced in 48 transfers (2.3 embryos/ET). One live birth, one miscarriage, and eight ongoing pregnancies were obtained (22%/ET). Conclusion: Preclinical practice on aged unfertilized oocytes seems useful before starting clinical ICSI, as the high initial oocyte damage can be reduced and subsequent clinical treatment successfully applied.