In certain situations, your doctor may recommend other procedures before embryo transfers:

• Assisted hatching

About five to six days after fertilization, an embryo  “hatches” from its surrounding membrane (zona pellucida), allowing it to implant into the lining of the uterus. If you’re an older woman, or if you have had multiple failed in vitro fertilization attempts, your doctor might recommend assisted hatching-a technique in which a hole is made in the zona pellucida just before transfer to help the embryo hatch and implant. assisted hatching is also useful for eggs or embryos that have been previously  frozen as the process can harden the zona pellucida.

• Preimplantation genetic testing

Embryos are allowed to develop in the incubator until they reach a stage where a small sample can be removed and tested for specific genetic diseases or  the correct number of chromosomes, typically after five to six days of development. Embryos that don’t contain affected genes or chromosomes can be transferred to your uterus. While preimplantation genetic testing can reduce the likelihood that a parent will pass on a genetic problem, it can’t eliminate the risk. Prenatal testing may still be recommended.