EMBRYO AND OOCYTE FREEZING

Assisted reproductive technology has achieved its higher success with different technique optimization, in the field of embryology cryopreservation dramatically improved the success rates of IVF cycles. cryopreservation simply means preserving cells and tissues in live conditions restricting the metabolism to a standstill.

Embryo freezing

This technique helps us to store the surplus embryos formed in 1 IVF stimulation cycle. it helps couples to store their excess biological embryos for the future and they need not go another stimulation, thus saving their expenditure as well as it gives them the opportunity just to undergo embryo transfer cycles in case 1st embryo transfer becomes negative.

In controlled ovarian hyperstimulation when the oestrogen goes higher or there are symptoms of
0HSS, we can avoid the fresh transfer and store all the embryos for the future.

 

Procedure

  1. Slow Freezing Method: It is a slow freezing method where embryos are exposed to 1 -2 mol/l solutions of permeable and
    nonpermeable CPAs and then loaded into the straw, sealed and cooled to -6 degrees centugrade rapidly. Here the embryos can undergo cell dehydration due to ice crystal formation.
  2. Vitrification Method: It is a form of repeat cooling in which a very high concentration of CPA solidifies without forming ice
    crystals. Hence this is an improved technique and gives almost 100% retrieval after thawing.

It gives significantly higher survival and clinical pregnancy rates when compared with slow freezing.

Advantages of embryo freezing

  1. Permits to do a single embryo transfer
  2. Excess embryos can be used for future.
  3. Increases cumulative pregnancy rate rather than fresh cycle.
  4. To achieve voitures free clinic
  5. Can avoid embryo transfer in cases of poor endometrial lining, fluid collection in uterine cavity, serum progesterone more than 1.5 NG per ml etc.
  6. A patient going PGS.

Timing Of Cryopservation

It can be done in day 3 of embryo which is a morula stage so can be done in day 5 i which is a blastocyst embryo. The blastocyst embryo storing has certain advantages which helps in a better survival rate 98% and implantation rate of 49%.

oocyte freezing

Indication

  1. Fertility preservation in malignant and premalignant conditions.
  2. Genetic conditions like turner’s, X syndrome deletion of X chromosome where there is a chance of early ovarian failure
  3. Egg donor programs
  4. Delaying motherhood
  5. Avoids legal and ethical restrictions of embryo cryopreservation.
  6. When there is non-availability of sperms during ovum pick up.
  7. Accumulation of oocytes sides in a case of a poor responder.

Factors affecting the outcome of Cyprus preservation

There are several factors that affects the survival of oocytes like the stage of maturation, size and quality of oocytes, stimulation protocols, freezing methods and most importantly the age of the patient and the cause of infertility.