What is assisted hatching?
Assisted hatching is a laboratory procedure whereby the shell (zone pellucid) around the early 2-3 day old embryo is mechanically weakened in a way which assists that embryo to “hatch” from the zona more easily and to allow implantation into the lining uterus.
The assisted hatching technique was commenced in 1990 by a team led by Dr. Jacques Cohen at Cornell in New York. Since then a large number of reputable centers have commenced these procedures with an improvement in the hatching rates and subsequent implantation and pregnancy rates in a particular group of women who could benefit from this procedure.
Who considers assisted hatching?
Normally the “hatching” process involves the rupturing and dissolving of the zona pellucid at about 120 hours (5 days) after fertilization. This allows the embryo to leave the protected environment of the zona pellucid and commence implanting into the lining of the uterus.
Normally, the uterine lining is in a condition which is receptive for implantation for about 48 hours (i.e. From 120 to 168 hours after fertilization). However in women who undergo ovarian stimulation (as occurs in IVF/GIFT etc) this window of implantation is brought forward to between 72 and 120 hours after fertilization. Thus, if hatching does not occur, or occurs after 120 hours, implantation will be unsuccessful and a pregnancy will not commence. Those women who would benefit, from assisted hatching include all those who have either thicker (or therefore harder) (but normal thickness) zona.
The following conditions would benefit from assisted hatching:
- Older eggs-eggs from older women generally have thicker zona than those from younger women.
- Reduced embryo energy levels-in some women who have had repeatedly unsuccessful art cycles it is possible that the cellular energy level required for normal hatching may be insufficient.
- Asymetry between the “window of implantation” and the hatching time of the embryo, (if the embryo hatches too late for the uterine lining to accept it).
- Frozen/thawed embryos-it is evident that the freezing/thawing process can harden the zona.
Benefits of assisted hatching
Assisted hatching allows embryos to “hatch” with greater ease and earlier than otherwise would have occurred. It also assists embryos to “hatch” which might not have otherwise done so. The other benefits are than, in ensuring a greater percentage of embryos “hatch” and “hatch” earlier then a greater percentage will implant.
Pregnancy rates have increased up to 2 times in those patient groups who have been shown to benefit from this procedure.
Assistance to improve the percentage of embryos to hatch and implant will significantly increase the chances of conception and consequently increase the chances of producing more than one child
Disadvantages of assisted hatching
In some instances, the creation of a weakness in the zona pellucid will not be enough to improve the chances of adequately hatching.
There is an extra fee for couples who wish to use assisted hatching above what is normally charged for IVF. Please speak to the Accountant who will discuss this with you before you proceed.