Human embryos, formed by an egg and a sperm, are quickly surrounded by a coating that forms a protective barrier so that only one sperm fertilizes the egg. When this package enters the uterus, this coating must dissolve in order for the embryo to attach itself in the lining.
Normal embryos with a thin barrier coating have few difficulties during in vitro fertilization (IVF). When the shell is less than optimal, a process called “assisted hatching” is recommended.
This assistance is most helpful on embryos of women older than 38 years of age, or, younger women if the shell is thick or the embryo quality is fragile.
According to the American Society for Reproductive Medicine, assisted hatching may be recommended if:
- embryos are fertilized by injecting a sperm directly into an egg
- a frozen-thawed embryos (FET) is used
- the woman has a high follicle stimulating hormone (FSH) level
- couples have failed to achieve a pregnancy in a prior IVF cycle
- embryos are transferred at day three
Because assisted hatching is a difficult technique, the success is dependent on the embryologist’s experience and technique.