Assisted Hatching is a procedure that "thins" the outer coat (zona) of the embryo immediately prior to transfer to the uterus. This thinning helps the embryo "hatch" once it is placed back in the patient's uterus. Hatching must occur prior to embryo implantation; pregnancy begins after the embryo implants in the uterus.
Under certain circumstances, some embryos may need help escaping ("hatching") from the zona. Assisted hatching is a technique whereby a small hole is created in the zona pellucida by the controlled exposure of small area of the zona to an acidic culture media solution.
Assisted hatching is not routinely used in our lab, but there are some general guidelines where it may prove helpful in encouraging implantation. Assisted hatching is recommended for older patients (40 and older), for patients with thickened zonas (often appreciated at the time of ICSI), for patients who have had several unsuccessful cycles with no clear-cut reason and for patients undergoing thawed embryo.