Assisted hatching in an in vitro fertilization programme.

Assisted hatching was performed on 37 women (IVF, n = 12; micromanipulation, n = 25), who were at risk of poor implantation after in vitro fertilization and micromanipulation, and who had previous cycles of failed implantation. A total of 292 oocytes was retrieved (7.9 per cycle) of which 90 were subjected to IVF and 202 were micromanipulated. Assisted hatching was performed on day 3 of culture, on six- to eight-cell embryos, by the technique of mechanical partial zona dissection. All the patients undergoing the procedure of assisted hatching had embryos with thick zonae, greater than 15 microns. Assisted hatching was performed on 39 embryos (55.7%) in the IVF group and 104 embryos (77.6%) in the micromanipulation group. The damage rate after hatching was 1.4%. The pregnancy rate per cycle was 50% in the IVF group and 44% in the micromanipulation group, compared with 10% (IVF) and 19.2% (micromanipulation) in the control groups. Assisted hatching, by partial zona dissection, results in significant improvement in pregnancy rates in women more than 38 years of age, who have a thick zona and with previous poor implantation results. This paper reports the first pregnancy in India by the technique of assisted hatching (partial zona dissection).