A. Stein et al., ASSISTED HATCHING BY PARTIAL ZONA DISSECTION OF HUMAN PREEMBRYOS IN PATIENTS WITH RECURRENT IMPLANTATION FAILURE AFTER IN-VITRO FERTILIZATION, Fertility and sterility, 63(4), 1995, pp. 838-841
Objective: To examine the potential of the partial zona dissection tec
hnique to promote successful implantation by assisting embryo hatching
after IVF. Design: The study and the control group included 72 and 82
patients, respectively, each had undergone at least three failed IVF-
ET attempts. Assisted hatching was performed on four- to six-cell stag
e embryos by creating a slit in the zona pellucida using the partial z
ona dissection technique. After 90 minutes incubation (5% CO2, 37 degr
ees C), the embryos were transferred to the uterus. Setting: Infertili
ty and IVF Unit of an academic tertiary referral medical center. Resul
ts: In the assisted hatching group, 230 micromanipulated embryos were
replaced (3 or 4 treated embryos per patient) compared with 295 nonman
ipulated embryos in the control group, Clinical pregnancy rates (PRs)
were similar in the assisted hatching and control groups (n = 15; 20.8
% and n = 12; 14.6%, respectively). However, the contribution of assis
ted hatching by partial zona dissection to successful implantation was
related to the patients's age: patients older than 38 years showed a
markedly higher PR after assisted hatching: 23.9% in the study group c
ompared with only 7% of the controls. Conclusions: These results demon
strate that assisted hatching by partial zona dissection is a quick an
d efficient method that does not induce any visible damage to the embr
yos replaced. In a selected group of patients (aged over 38 years, who
have failed to conceive in at least three previous IVF attempts) it s
ignificantly increases the chances for pregnancy after ET.