ETschool
Member
- Joined
- Apr 6, 2013
- Messages
- 24
- Reaction score
- 0
Variability of Pregnancy Rates from Frozen/Thawed/Transferred Embryos
The problem of low pregnancy rates following the transfer of previously frozen embryos has significantly decreased over the years, but it still does occur as demonstrated in a recent court case. Usually the transfer technician is accused of unacceptable quality work as he/she is the last person to handle the embryo. However, fault may be due to many other persons in the steps to produce the final product e.g. selection of poor quality embryos to freeze, unacceptable freezing techniques, poor embryo storage practices, recipients too fat or too thin, inaccurate heat detection, inadequate records etc...
As the technician performing the work, or as the donor owner selling the embryos, there is an excellent method to protect oneself: Following embryo and egg collection there are in most cases eggs and degenerate embryos observed. Prepare these normally discarded eggs and embryos for freezing the same as for valuable embryos and place them all in one straw. Around -30°C place the test straw in the liquid nitrogen tank for approximately one minute. Remove this straw from the tank, thaw and examine the eggs and embryos and record the results. If there is a problem with the freezing method there will be many zona cracks. About 10 to 15 percent of zonae will have one crack even with excellent freezing techniques. Eggs are quite acceptable for this technique.
SUPEROVULATION PROTOCOL MODIFICATION:
Guerra et al recently published a modified superovulation protocol which appears very promising. By extending the 4 day FSH treatment to 7 days, injecting the same amount of FSH, they observed a significant increase in CLs produced. This treatment did not increase the number of follicles recruited but the longer treatment schedule gave the smaller follicles time to mature and be able to ovulate. Extending the superovulation treatment may be useful for those donors producing too few embryos.
May all of your flushes be successful!
Dr. Peter Elsden
http://www.ETschool.com
References:
Guerra et al Theriogenology 84 (2015) 467-476
The problem of low pregnancy rates following the transfer of previously frozen embryos has significantly decreased over the years, but it still does occur as demonstrated in a recent court case. Usually the transfer technician is accused of unacceptable quality work as he/she is the last person to handle the embryo. However, fault may be due to many other persons in the steps to produce the final product e.g. selection of poor quality embryos to freeze, unacceptable freezing techniques, poor embryo storage practices, recipients too fat or too thin, inaccurate heat detection, inadequate records etc...
As the technician performing the work, or as the donor owner selling the embryos, there is an excellent method to protect oneself: Following embryo and egg collection there are in most cases eggs and degenerate embryos observed. Prepare these normally discarded eggs and embryos for freezing the same as for valuable embryos and place them all in one straw. Around -30°C place the test straw in the liquid nitrogen tank for approximately one minute. Remove this straw from the tank, thaw and examine the eggs and embryos and record the results. If there is a problem with the freezing method there will be many zona cracks. About 10 to 15 percent of zonae will have one crack even with excellent freezing techniques. Eggs are quite acceptable for this technique.
SUPEROVULATION PROTOCOL MODIFICATION:
Guerra et al recently published a modified superovulation protocol which appears very promising. By extending the 4 day FSH treatment to 7 days, injecting the same amount of FSH, they observed a significant increase in CLs produced. This treatment did not increase the number of follicles recruited but the longer treatment schedule gave the smaller follicles time to mature and be able to ovulate. Extending the superovulation treatment may be useful for those donors producing too few embryos.
May all of your flushes be successful!
Dr. Peter Elsden
http://www.ETschool.com
References:
Guerra et al Theriogenology 84 (2015) 467-476
