CRYO-Preservation -Sperm, Oocyte, Embryo
In this modern hi-tech life we are caught amidst altered lifestyle, decreasing fertility levels, higher incidence of cancer in young individuals, increasing cost of treatment and inspite of advanced scientific technology we still cannot assure 100% success with ART. The current focus in the field of assisted reproduction is to come up with techniques which can improve the success rates, decrease the treatment cost and at the same time preserve the fertility potential of young individuals. Cryopreservation of gametes and embryos is one such initiative which is gaining importance in infertility management.
VARIOUS REPRODUCTIVE TISSUES THAT ARE FROZEN AT OASIS
After several decades of research we are now routinely cryopreserving semen, zygote stage embryos, cleavage stage embryos and blastocyst stage embryos.With recent advancements its possible to successfully cryo-preserve oocytes and testicular tissue. Preservation of ovarian tissue is still at research level with variable success rates. Further research is awaited to validate their use in clinical practice. We are one among the few Indian clinics to offer oocyte and embryo freezing with excellent post thaw survival & implantation rates.
TECHNIQUES TO CRYO-PRESERVE GAMETES & EMBRYOS
After several years of research slow cooling and Vitrification are the only two methods that are routinely used to cryo-preserve.
Slow freezing is the most widely used method of cryopreservation. During slow freezing, the gametes/embryo are exposed to subzero temperatures in a controlled rate with the use of low concentration cryoprotectants. Though it has got reasonable success rates, ice crystal formation cannot be avoided and this affects the post thaw survival rates and there by the success. This technique is now been replaced by an ultra cooling technique called Vitrification.
Vitrification comes from the Latin word vitrum, meaning glass. In the context of freezing embryos, vitrification is the process whereby the solution containing the gametes/embryos is cooled so quickly that the structure of the water molecules doesn't have time to form ice crystals and instantaneously solidifies into a glass-like structure. Unlike previous slow freeze methods, which took up to two hours to lower the embryo to the correct temperature, vitrification takes just a few minutes; it is an easier technique with better post thaw survival rates and better success rates
In the process of Semen freezing, semen is scollected and mixed with equal amount of cryoprotectant (chemical to protect the sperm cells from cryo-damage) and stored in Liquid nitrogen.
Indications for Semen Freezing
- Prior to Vasectomy
- Prior to cancer treatments like chemo/radiotherapy
- As a part of semen banking
- In cases with severe male factor infertility
- In cases prone to develop azoospermia
- As a part of IVF cycle, when the partner has got problems with collecting semen on demand
- In couples where the partner is a frequent traveler
Pre-requisites for semen freezing
- Three days abstinence
- Screening for HIV1&2, Hepatitis -B&C, VDRL
- Consent for freezing
How long can the semen be frozen?
The semen can be frozen for many years provided the method of freezing is done properly.
While men are capable of manufacturing 1000 sperm in the space of one heartbeat up to a ripe old age, the female of the species steadily but surely loses her eggs from birth to menopause, with an accelerated loss from the midthirties onward. We believe that the time has come to consider redressing the balance between the male and female fertility potential now that we apparently have the technology to do so. The successful preservation of oocytes by vitrification will provide the ''aging'' woman who has had to delay her childbirth, for any reason, the opportunity to conceive and deliver using her own oocytes at the time she decides.
While ovum donation has been highly successful in providing a solution for women with incompetent oocytes, the preference of using their own genetic material is overwhelming
Indications for Oocyte Vitrification
Prior to cancer treatments like chemo/radiotherapy
Prior to organ transplant therapy (liver transplant, bone marrow transplant, etc.;)
In severe Poly Cystic Ovarian Syndrome cases
Single women wanting to preserve the fertility
In cases where male partner fails to produce semen sample on the day of IVF after egg pickup and ICSI/IVF needs to be posponed
Pre-requisites for oocyte vitrification
HIV, Hepatitis B&C and VDRL screening of the women whose eggs will be frozen
The women needs to undergo controlled ovarian stimulation with reproductive hormones
Eggs will be collected under general anesthesia and checked for maturity
only mature eggs will be frozen using an ultra rapid freezing technique called VITRIFICATION
Also read Fertility Preservation