[The effect of assisted hatching on patients repeatedly failed to conceive by in vitro fertilization].

Assisted hatching (AHA) techniques were used in 67 patients who had repeatedly failed to achieve conception by conventional IVF-ET in spite of replacement by good quality embryos. The age of the female patients ranged from 28 to 44 years and the causes of their infertility included tubal factors (n = 33), male infertility (16), endometriosis (8) and unexplained causes (21). Zona drilling with acid Tyrode's solution was performed on 248 embryos in 88 cycles approximately 72 hours after oocyte collection. One to 4 embryos were transferred to the uterus 1 to 4 hours later. Twenty-four clinical pregnancies were established (27.3%) and the implantation rate was 15.3% (38/248). These results were both significantly higher than those for our conventional IVF-ET (22.0% pregnancy rate and 10.7% implantation rate) (p < 0.05). Eleven babies have been born normally and there are 16 current pregnancies. These preliminary findings suggest that AHA might be beneficial for patients in whom conventional IVF-ET had repeatedly failed.