In Vitro Fertilization: Cryopreservation

Cryopreservation or Embryo cryopreservation is an integral part of contemporary In Vitro Fertilization procedures. During a typical IVF treatment schedule, multiple embryos are prepared outside the women’s body, i.e. in an artificial environment. This is purposely done to ensure that there is no shortage of embryos when testing and choosing the best one for implanting in the uterine tissue of the woman. Thus, the artificially-fertilized embryos need to be stored since at one time, about a couple of selected embryos are placed within the uterus.

Basics of In Vitro Fertilization Cryopreservation

The remaining embryos need to be preserved in a manner that does not damage their viability for IVF and enables the fertility specialist to access them easily. Please note that an IVF treatment might stretch up to a month or more, i.e. until an implanted embryo is able to successfully initiate the pregnancy. Thus, the storage medium for embryos has to be very efficient. This storage requirement is met by Cryopreservation—freezing of embryos at sub-zero temperatures.

Embryos are usually frozen immediately after fertilization during their pronuclear stage of development. This ensures the longevity of the embryos and prevents unnecessary expenditure and discomfort to patient by negating the need to repeatedly extract the oocytes (eggs). Embryos might also be stored at a slightly later development stage, called the blastocyst stage. The freezing approach is dependent upon the kind of cryopreservation technique adopted by the IVF clinic.

Major Advantages of Embryo Cryopreservation

  • Freezing embryos derived during the initial stage of IVF schedule negates the side-effects of ovarian hyperstimulation syndrome (OHSS) being passed on to the womb.
  • Cryopreservation is highly recommended for women who are struggling with unstable menstruation, endometrial polyps, extensive uterine bleeding and other illnesses that limit IVF treatment.

Cryopreservation and Embryo Donation

The IVF couple is also asked to consider cryopreservation for embryo donation purposes. Here, after the successful initiation of pregnancy, the remaining, frozen embryos are donated to couples who are struggling with their IVF treatment. This is done in strict coherence with various laws governing the niche of embryo donation and the comfort of the IVF couple in this regard.

Possible Cryopreservation Complications

The choice of using frozen/thawed embryos for inducing pregnancy is not applicable or suited to every woman. Some IVF women might show a high rejection rate for such embryos. Though cryopreservation is aimed at extending the life of embryos, it may cause the early death of some embryos since not every embryo is capable of surviving the freezing temperatures.

Embryo freezing might be the standard procedure for an IVF clinic, but it puts forth additional expenses too. This might not be acceptable to the IVF couple, and they might object to the use of this technology. Many clinics regard cryopreservation as a standard part of IVF and don’t disclose it at the time of IVF counseling. Couples might object to this technology later, during the treatment, leading to arguments.

Embryos are stored in containers that are cooled with liquid nitrogen. The use of a chemically-derived agent for storing embryos has given rise to questions regarding the safety of this procedure, though no related complications have been reported due to the cooling medium.

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