A study failing to determine significant benefits from assisted hatching: Patients selected for advanced age, zonal thickness of embryos, and previous failed attempts
Wr. Edirisinghe et al., A study failing to determine significant benefits from assisted hatching: Patients selected for advanced age, zonal thickness of embryos, and previous failed attempts, J AS REPROD, 16(6), 1999, pp. 294-301
Purpose: Pregnancy and implantation rates after mechanical assisted hatchin
g (AH) in patients aged greater than or equal to 38 years, with embryos gre
ater than or equal to 15 mu m in zonal thickness and two or more failed att
empts, were assessed at two infertility centers using fresh and frozen embr
yo transfer (FET) cycles.
Methods: AH was performed on 3-day-old embryos. Spare embryos cryopreserved
at the two-pronucleus stags were subjected to AH after 2 days of culture a
nd transferred to artificially prepared uteri.
Results: In fresh cycles, no significant differences in pregnancy rates (cl
inical and ongoing) and implantation rates were observed between the AH and
the controls for all three selected patient groups (Centers 1 and 2). In F
ET cycles AH tended to give poor results for greater than or equal to 38 ye
ar olds (clinical pregnancy rates of 0 and 5.0% with AH vs 13.3 and 16.7% f
or controls at Centers I and 2, respectively). With AH, embryos with thick
zonae implanted to the same extent as those in the control group and achiev
ed pregnancies for patients with multiple failures (four to six attempts fo
r some) in both fresh and FET cycles.
Conclusions: AH failed to show significant benefits in all three patient gr
oups. A larger study group may confirm the effects of AH on frozen/thawed e
mbryos and outcomes for multiple failure cases.