Cryofreezing

It combines of two Categories:

Embryo Cryo Preservation

What it means?
In IVF procedures ovaries are stimulated to produce 10-15 eggs. All these eggs can lead to healthy embryos after fertilization. Only one or two embryos are transferred. Remaining spare embryos can be preserved for future use by freezing these embryos.

Who are suitable candidates?

  • All IVF cycles which have spare good quality embryos can be benefitted by cryofreezing of embryos.
  • When embryo transfer is cancelled in same cycle due to various indications and unavoidable circumstances all embryos can be frozen
  • Now there is a movement for elective freezing of all embryos because results are equal or even better in frozen cycles
  • For fertility preservation when immediate pregnancy is not possible due to medical or social reasons like chemotherapy for cancers or carrier choice.

 
Who should not get embryo-cryofreezing?
There are no contraindications for embryo-cryofreezing. Couples with infections like hepatitis may be denied freezing by the hospital because risk of cross contamination.

What are its main steps?

  • Step-1 After embryo transfer spare good quality embryos are separated.
  • Step-2 Consent from both partners is taken.
  • Step-3 Embryos are mixed with protecting solutions.
  • Step-4 Embryos are loaded in freezing straws.
  • Step-5 Then these devises are slowly cooled in a programmed freezer to -80 degree C and then plunged and stored at -180 degrees C in liquid nitrogen. An alternate method is called vitrification in which embryos are directly plunged in liquid nitogen at -180 degrees. Both method are highly successful.
  • Step-6 A detailed log is kept for identification.

 
Thawing:
Thawing is done only when embryos are to be transferred back to the uterus. During thawing also these are slowly brought to room temperature and passed through solutions to bring to normal. The embryos are further grown in laboratory for evidence of further development. Then embryos are transferred to uterus.

Advantages:

  • It is a highly effective technique. Success rates per cycle are in the range of 40-45 % and almost equal to fresh cycles.
  • This is a highly cost effective technique. In good cases one can get the benefit of 2 or 3 ETs with one OPU with at much less cost. Moreover same embryos can be used for second child.

Disadvantages:

  • Additional cost.
  • Legal status.
  • Allowed by Indian Council of medical research guidelines when done with the consent of both partners. The child thus born has all legal rights and obligations. Custody issues may arise in the event of divorce or death of one or both partners.

Sperm Cryopreservation

What it means?
Sperm cryofreezing means freezing the semen for storage for future use.

Who are suitable candidates?

  • Donated semen
  • Backup for IVF and IUI cases.
  • Long term storage for fertility preservation e.g. before chemotherapy.

 
Who should not get sperm -cryofreezing?
There are no contraindications for sperm-cryofreezing. Couples with infections like hepatitis may be denied freezing by the hospital because risk of cross contamination.

What are its main steps?

  • Step-1 Appropriate consent is taken.
  • Step-2 Male partner is investigated to exclude common illnesses and infections.
  • Step-3 Semen is collected after masturbation.
  • Step-4 Semen is mixed with protecting solutions.
  • Step-5 Mixed mixture loaded in freezing straws.
  • Step-6 Then these straws are slowly cooled in a programmed freezer to -80 degree C and then plunged and stored at -180 degrees C in liquid nitrogen. An alternate method is called vitrification in which semen is directly plunged in liquid nitrogen at -180 degrees. Both method are highly successful.
  • Step-7 A detailed log is kept for identification.

 
Thawing:
Thawing is done only when semen is to be used. During thawing also these are slowly brought to room temperature and passed through solutions to bring to normal. The semen is checked for sperm count and motility before using for IVF or IUI.

Advantages:
It is a highly effective and relatively low cost technique. The sperm banks store different samples which can be used on demand. Semen is quarantined before releasing for use . This time is generally equal to the window period of HIV infections . This time gap ensures safety of samples.

Disadvantages:

  • Sperm survival is reduced. Success rate with IUI with frozen samples is reduced as compared to fresh samples.
  • Legal status.
  • Allowed by Indian Council of medical research guidelines when done with the consent of both partners. The child thus born has all legal rights and obligations. Custody issues may arise in the event of divorce or death of male partner when semen was collected for self-use.

Frozen Embryo transfer

What it means?
The cryopreserved embryos are transferred to woman’s uterus at some date after IVF cycle.

Who are suitable candidates?

  • patients for whom spare embryos have been frozen after fresh IVF cycle
  • When embryo transfer is cancelled in same cycle due to various indications and unavoidable circumstances all embryos can be frozen
  • If patient is planning for next pregnancy after having conceived in previous IVF cycle
  • Embryos were frozen for fertility preservation when immediate pregnancy not possible due to medical or social reasons like chemotherapy for cancers or carrier choice.

 
What are its main steps?

  • Patient is given hormonal medicines for development of good endometrium; or transfer can be done in natural cycle also.
  • Serial ultrasound is done to assess quality of endometrium and day of transfer decided accordingly
  • Frozen embrys are thawed on day of transfer and quality of embryos assessed
  • Good quality embryos are transferred to the uterus under ultrasound guidance

 
Advantages:

  • Very good success rate (40-50%), even higher than fresh cycle according to few studies
  • no need to undergo fresh cycle.

 
Disadvantages:

  • Patient has to bear cost of cryopreservation