Cryopreservation or freezing is a technique, in which the body cells/ tissue are frozen in ice for use at a later date. The frozen specimen is recovered intact when it's time to use the by a process called thawing. This technique is now used quite commonly in fertility management and can be used to freeze eggs, sperms or embryos depending on the requirement. Freezing technology has evolved over time and the pregnancy rates using frozen sperms/ eggs/ embryos are as good as with fresh ones.
The technique of cryopreservation has evolved over time, with vitrification being a major breakthrough in this field. The process of vitrification involves cooling the embryos rapidly, which turns the cellular content into a glass like substance without allowing any time for formation of ice crystals. Ice formation risks the cell rupture because water expands when it forms ice. The embryos are then dipped in liquid nitrogen and stored in at ¬–196 degree centigrade. This brings all cellular activity to a halt and allows the embryos to remain viable for indefinite period of time. The recovery rate on thawing the vitrified embryos is excellent. Embryos can be frozen at any stage of development from day 1 to day 5.
Indications for embryo freezing:
To improve pregnancy rate - There can be significant hormonal fluctuation in a woman during ovarian stimulation, which may reduce the success rate of embryo transfer done in the same cycle. Embryo transfer in these women can be deferred to the subsequent cycles when the woman's hormonal status is more settled and receptive for embryo.
To preserve the extra good quality embryos formed after IVF/ ICSI - These frozen embryos can be used later in case the initial transfer fails or the couple decides to try for another child after a first successful embryo transfer.
In hyper-stimulated women - Embryo freezing reduces the complications rates in patients who are hyper stimulating, as embryo transfer can be deferred to a later (cold) cycle when the physiological status of the woman is more settled.
Embryo freezing offers an option to couples desirous to having a child later, but are at risk of losing their fertility potential because of some surgery or gonadotoxic treatment like radiotherapy or chemotherapy.
Eggs can also be frozen using the technique of “vitrification”.
Indications of egg freezing:
Women with advanced age, but still waiting for a right partner, can get their eggs cryopreserved for use in future.
For fertility preservation in fertile women undergoing any treatment that can suppress or reduce their fertility after the treatment- such as chemotherapy, pelvic radiation, surgery.
Sperm freezing is a rather simpler and well defined procedure and has been in use for decades. Sperms stand the freezing process very well and can be thawed easily.
Indications of sperm freezing:
As a backup in cases where the male partner may not be available on the day of IUI/ IVF to provide fresh semen sample.
When there is apprehension of the male partner not being able to produce a semen sample on the day it is needed.
Before the male partner is to undergo treatments like chemotherapy, which will likely affect his sperm count adversely and even make him azoospermic.
In men with oligospermia where multiple semen samples may be frozen to accumulate sperms.
In azoospermic males where the sperms have been recovered surgically using techniques like MESA, PESA, TESA. Sperms can be frozen to help the patient avoid having to undergo the surgery again.
One of the biggest challenges in IVF is the ability to select and transfer an embryo with the best implantation potential and highest probability of resulting in a pregnancy. The traditional practice to achieve a higher probability of implantation and pregnancy has been to transfer more than one embryo in the uterus, typically on the 2nd or 3rd day of development. Blastocyst is better alternative thank day 2 or day 3 embryo, which gives us clear benefits in terms of better pregnancy rate while transferring fewer embryos.
An Embryo that has grown for 5 to 7 days and has achieved 2 distinct cell types called inner cell mass and trophectoderm is called as blastocysts. Since this is an advanced stage of embryo growth, such selection of embryos based on their growth potential enhances the chances of implantation and improves the chances of achieving pregnancy without putting the woman at risk of multiple pregnancies and its complications such as prematurity, IUGR and foetal loss.
Laser assisted hatching
Laser assisted hatching is a laboratory procedure performed on the embryo before the embryo transfer. In this technique a very small hole is made in the outer shell of the embryo (called as the zona pellucida) using a laser beam, before placing the embryo in the uterus. As part of normal process of implantation, the embryo has to hatch out from the zona pellucida in order to implant in the uterus. Therefore, making a hole in the zona pellucida of the embryo before placing it in the uterus assists the embryo in coming out of this shell and facilitates implantation.
Indications of laser assisted hatching:
Women with recurrent implantation failure.
Women undergoing frozen embryo transfer– Freezing tends to harden the zona pellucida of the embryo, which may be a little more difficult for the embryo to breach. Thus, frozen embryo benefits from assisted hatching as it increases the chances of successful implantation.
Thick Zona - Zona pellucida >40 microns thick.
Embryo adoption is a good option for infertile couples having both male and female factors, who are unable to produce enough good quality eggs and sperms. Although it can be debated whether these patients will benefit more by adopting a child or an embryo, we give our patients both these options and discuss the pros and cons of both the options. This helps them make a well informed decision on how to realise their dream to have a child.
Many a times, couples having suffered from long term infertility prefer to adopt an embryo, as it gives them the opportunity to go through the process of pregnancy and child birth. Embryo adoption also allows the adopting couple to avoid social stigma of adoption by keeping the whole process discrete and screen certain physical characteristics of the donating parents.
Surrogacy is an arrangement when another woman carries and gives birth to a baby for the couple who want to have a child. It is a means of third party reproduction in which the surrogate is only a “gestational carrier” a woman who accepts to bear (or be pregnant with) the child of another woman who is incapable of becoming pregnant using her own uterus.
The gestational carrier provides a host uterus for the offspring, and does not contribute genetic material, i.e. is not the egg provider. The offspring’s genetic material may come from the egg and the sperm provided solely by the aspiring man, woman or couple, referred to as the “intended parents,” or in combination with donor egg and/or donor sperm, depending on the needs of the intended parents.
Indications for surrogacy:
A woman without a uterus, example congenital absence of uterus or post hysterectomy.
If a woman suffers from a disease, where carrying a pregnancy might be life threatening for her.
If the uterus is severely damaged so much so that it is incapable of carrying a pregnancy.