The Ronald O. Perelman and Claudia Cohen "Center for Reproductive Medicine" - of Weill Cornell Medical College

Assisted Embryo Hatching 

Embryos shed their outer cell coat, the zona pellucida, as part of the process by which they implant in the lining of the uterus in order to establish a pregnancy. For a variety of reasons, some embryos do not sucessfully hatch and subsequently cannot implant in the uterus.    

Performed in conjunction with an IVF cycle and prior to embryo transfer, assisted hatching involves an embryologist thinning or drilling through the zona pellucida of an embryo in order to make it easier for the embryo to shed its cell coat and implant (attach to the uterus). 

EAH.pngAbove, a-d: The assisted hatching process, including opening of the embryo's zona pellucida and removal of fragments obstructing the embryo's hatching

Assisted hatching can be useful for patients with embryos with harder or thicker zona pellucida, and for patients who have previously not succeeded with IVF.