What is Assisted Hatching?

Older brothers can certainly torment younger ones a great deal. My brother Steven is a typical middle child. As my eldest brother (and my protector in the family), Mike, always wanted to be like our surgeon father, it fell to Steve to be the “black sheep/bad boy” of the family. Part of this mission was to torture his younger, spoiled brother…yours truly. His favorite means of torture was psychological, although physical brutality, such as making me always play goalie in games of basement street hockey, was sometimes employed. Steve would alternatively tell me that I was found in the gutter by Mom and Dad (how else to explain the fact that there was 8 and 13 years between me and Steve and Mike respectively), or that I had been hatched not born. Little did he know that we all actually hatch as blastocysts prior to implantation. Well, children do grow up and now I am pleased to report that I enjoy an excellent relationship with my former tormentor. For his part, it is hard to describe the CEO of the suburban campus of Boston Children’s Hospital as a “black sheep” especially when he can get some really great Red Sox tickets…

So how about Assisted Hatching? There is a lot of recent questions posted on my INCIID Bulletin Board about AH. We have moved to limiting hatching to a subgroup of patients and recently purchased a laser for our embryology team to use in performing hatching as opposed to using chemical means. We currently have not performed AH on blastocysts but some clinics have done this procedure especially on embryos that form blastocysts on day 6 or 7.

Here then is the Question of the Day from the book that even my brother Steve enjoyed reading: 100 Questions and Answers about Infertility.



61. I was told I need assisted hatching. What is this, and why is it done?


Dr. Gordon’s older brother Steven used to tease him by claiming that he was hatched and not born, but actually all of us do “hatch” in early embryonic life. The human embryo hatches out of the eggshell (zona pellucida) at the blastocyst stage of development. Assisted hatching involves weakening the zona to facilitate the emergence of the embryo following its transfer into the uterus after IVF. Proponents of assisted hatching suggest that it increases implantation and pregnancy rates. Assisted hatching is almost always performed chemically. In this technique, a dilute acid solution is used to dissolve the external eggshell. Some clinics, however, perform mechanical hatching, in which a slit is made in the eggshell, or even laser-assisted hatching, in which a laser is used to thin the zona. (See Figure 5 © 1995 Humananatomy® Illustrated).


There is some controversy regarding which patients benefit most from assisted hatching, and the indications for assisted hatching remain somewhat unclear. Most clinics recommend this step in cases where the female partner is older than age 37, has diminished ovarian reserve with increased levels of FSH, or is undergoing a frozen embryo transfer (FET) with previously cryopreserved embryos. Patients who have previously failed IVF following replacement of good-quality embryos may also benefit from assisted embryo hatching. The risks of assisted hatching are believed to be quite low. There have been reports of increased rates of identical twinning following mechanical hatching (but not after chemical-assisted hatching). There is no evidence that assisted hatching harms the embryo or causes any increased rate of birth defects in children.