In natural conception, embryo hatching includes the spontaneous destruction of the membrane around the egg cell: the zona pellucida. This frees the embryo and prepares it for implantation in the uterus. In some cases, this membrane is abnormally thick and does not allow embryo hatching. Embryo implantation failures are considered to be at least partly due to the impossibility of breaching the zona pellucida. This means that the embryo cannot go on to implant itself into the uterus. The problem is more typical of older women, though it may be observed in all age groups.
Assisted embryo hatching is a micromanipulation method most often applied with embryos at the six to eight cell stage, directly prior to transfer. The micromanipulation involves breaching the zona pellucida and is thus assumed to help hatching and the early interaction between embryo and endometrium at the most critical early stage.
Laser Assisted Hatching (LAH)
The arrival of lasers allowed the development of precise techniques for embryo manipulation and assisting fertility. Laser assisted embryo hatching can drastically change the history of a series of unsuccessful embryo implantations into the uterine wall. The Sofia Hospital of Obstetrics, Gynaecology and Reproductive Medicine has the latest generation of laser assisted embryo hatching equipment: LYKOS™ by the Hamilton Thorne, Inc. company, a leading world supplier of reproductive medicine laser equipment.
Laser assisted hatching using LYKOS™ uses a tightly focused infrared beam to remove the zona pellucida in very precise steps. Before LYKOS™ came along, only mechanical or chemical methods could assist human embryo hatching in clinical conditions. Laser assisted hatching involves less embryo handling than other assisted hatching methods. Laser assisted hatching is also faster than other methods, the embryo spending less time outside the incubator.
What are the Indications for LAH?
LAH is not recommended as a routine procedure for all IVF patients. When determining LAH candidates, several factors are taken into account. They include age, hormonal status, embryo quality, the number of in vitro attempts, and whether frozen embryos are being implanted.
- Age: women over 37;
- Hormonal status: women with raised basis levels of FSH;
- Embryo quality: women with embryos with poor prognosis, including states such as thick zona pellucida, slow cell division or high degrees of cell fragmentation;
- Number of IVF attempts: women with one or more unsuccessful attempts;
- Frozen embryos: women using frozen/thawed embryos which may feature tougher zona pellucida.