Assisted hatching (AH) and Embryo transfer (ET/ KET)

Assisted hatching (AH)

The technique, in which an orifice is made by a laser or micro manipulative needle into the glycoprotein coat (zona pellucida) of the embryo, through which the embryo later leaves the coat (a process called hatching). This technique is recommended to be performed in embryos with a thick zona pellucida or in cryopreserved embryos where the cryopreservation process may induce changes in the hardness of the ovum shell.

The embryo is surrounded by a 13-15 µm thick protective envelope (zona pellucida). During the natural process of nesting, this envelope is gradually broken and the embryo is ready to be captured. In assisted reproductive procedures, it is sometimes necessary to disrupt the protective envelope by a special technique called assisted hatching. A laser is used to create a small hole in the zona pellucida through which the embryo later leaves the zona pellucida. The process of artificially disrupting the envelope helps the developing embryo to shed it and attach itself to the uterine wall, which increases the likelihood of achieving a viable pregnancy. This technique is recommended for embryos with a thick zona pellucida or for cryopreserved embryos, where cryopreservation may induce changes in the hardness of the embryo envelope. It is also advisable to use this method when the patient is older (38+) or has had previous unsuccessful cycles.

Indications for assisted hatching: higher age – the patients over 38 years of age, female patients with FSH elevations on day 3 (>10.0), female patients with previous failed pregnancy cycles, thick or abnormal zona pellucida, with cryopreserved embryos.

Embryo transfer (ET/ KET)

Embryotransfer (ET) is the gentle introduction of the embryo(s) into the uterine cavity through a thin catheter under ultrasound guidance. The embryo is introduced with a small amount of special fluid. The procedure is quick, painless and does not require anesthesia. The number of embryos introduced depends mainly on the age and health of the patient or the number of previous IVF cycles. Usually 1-2 embryos are transferred. The first pregnancy test is performed 14 days after the transfer.

In an IVF cycle, we usually obtain more healthy embryos than we subsequently use for a fresh transfer. The remaining embryos are frozen by vitrification and then stored at -196 °C. This allows us to store the embryos for a long time. As with traditional transfer, this is a simple, outpatient procedure in which the embryos are transferred into the uterine cavity after thawing. Cryoembryo transfer (KET) is less demanding in terms of the use of hormonal preparations. There is no need to stimulate the ovaries before transferring the thawed embryos, but only to prepare the lining of the uterus with drugs to receive the embryos. The exact transfer preparation plan is always determined individually by the doctor. Cryoembryo transfer can also be used for embryos that have been analysed by PGT.