Once the eggs are retrieved in an IVF cycle and combined with the sperm, the resultant embryos are placed in incubators and cell division begins. When the embryos reach the appropriate developmental stage, they are transferred to the uterus. The number of days in culture (usually 3-5 days) depends on how the embryos develop and whether or not blastocyst transfer is planned.
Once placed in the uterus, the embryo must, “hatch out” of its shell, the zona pellucida, thus facilitating its implantation into the uterine wall (the endometrium). Assisted hatching is a micromanipulation technique that involves thinning and making a small hole in the zona pellucida before the embryo is placed into the uterus. The opening in the membrane makes it easier for the embryo to break out of its shell and embed in the endometrium. Assisted hatching is performed on “day 3″ in most women over 37 years of age, in cases of previously unexplained failure to implant, or in anyone where the zona appears to be unusually thick.
The hole can be made with a laser, mechanically, or etched chemically using a dilute Acid Tyrode’s solution. The AH process does not damage the embryo and may improve implantation rates in certain couples.
Assisted hatching may be of benefit in older women, couples with unexplained infertility, women with failed implantation and other cases deemed appropriate by the physician