Wednesday, June 22, 2011

Is the success rate higher with fresh or frozen embryos ?

In the past, everyone agreed that the success rate was much higher with fresh embryos. This was primarily because the embryo freezing technology was not very good. We used a technique called slow freezing, and unfortunately, as a result of the freezing and thawing, upto 50% of embryos ( or the cells in the embryo) would die. This is because embryo cells ( called blastomeres) contain a lot of water; and the freezing process would lead to ice crystal formation within these cells. When these embryos were thawed, these crystals would cause cell death. Obviously, embryos will dead cells have a much poorer chance of implanting, and most labs were resigned to this fact that the process of freezing and thawing would cause damage to some embryos. However, it was still well worth freezing, because the success rate for the embryos which survived the insult of the slow freezing and thawing had excellent implantation rates !

The good news is that the slow freezing technology has now been replaced by ultra-rapid freezing. This is called vitrification, and is the only freezing process we use routinely in our lab today. We have stopped slow freezing for the last 2 years, because the success rates with vitrification are so much better.

In fact, when vitrification is done by an expert, the survival rate is nearly 100% - which means practically all the cells in the embryo survive the freezing and thawing intact.

This is a huge advance, because we can now freeze supernumerary embryos routinely, and we are confident that they will survive the thaw !

Vitrification is a tricky process and does have a steep learning curve, which means that not all labs will have a good success rate with it. This is why some labs still use the older slow freezing technique, because they have more experience with it, and are skilled at doing this. It's sometimes hard to teach an old dog new tricks !

Since the survival rate of embryos after vitrification is so good, we have found that our success rate after transferring these frozen embryos is often better than with fresh embryos transfer. This may seem quite counter-intuitive ! After all, if we are transferring the top embryos in the fresh cycle, and freezing only the supernumerary embryos ( which are presumably not of as good quality), how could this be possible ?

There are 2 reasons for this.

1. The number of fresh embryos we transfer has now been cut down to 2-3 ( or even one, when we are transferring blastocysts

2. The uterine lining is far more receptive in a non-IVF cycle. During IVF, the meds we use for superovulation can cause the uterine lining to be out of synch with the embryo. In a frozen cycle, we can prepare the uterine lining, till it's maximally receptive for implantation !

This means that it's possible that IVF clinics will soon start moving towards doing more frozen embryo transfer cycles than fresh cycles ! ( In fact, the Kato clinic in Japan which does about 10000 cycles per year) does not transfer any embryos at all in the fresh cycle ! They electively vitrify all the blastocysts and transfer in the subsequent cycle - and they have an extremely high pregnancy rate.

What does all this mean for you ?

1. Before you start your IVF cycle, confirm that your clinic uses vitrification for freezing embryos; and they are good at this
2. Don't ask your doctor to transfer more than 1-2 embryos
3. Be proactive about freezing your spare embryos
4. Even if you do not get pregnant in your fresh cycle, do not lose heart. The chances of success with vitrified embryos is still excellent !

Enhanced by Zemanta

7 comments:

  1. Anonymous3:26 PM

    typo in sentence: The good news is that the slow freezing technology has not been replaced by ultra-rapid freezing.
    NOT should be NOW

    but great blog!
    kind regards

    ReplyDelete
  2. Thanks so much for pointing this out - have fixed this :)

    Dr Aniruddha Malpani, MD
    Malpani Infertility Clinic, Jamuna Sagar, SBS Road, Colaba
    Bombay 400 005. India
    Tel: 91-22-22151065, 22151066, 2218 3270, 65527073

    Helping you to build your family !

    My Facebook page is at www.facebook.com/Dr.Malpani

    You can follow me on twitter at http://twitter.com/#!/drmalpani

    Watch our infertility cartoon film at http://www.ivfindia.com

    Read our book, How to Have a Baby - A Guide for the Infertile Couple,
    online at www.DrMalpani.com !

    Read my blog about improving the doctor-patient
    relationship at http://blog.drmalpani.com

    ReplyDelete
  3. Anonymous4:45 PM

    Is there any hope in freezing an embryo that only reached morula on D6 ? The lab won't culture it beyond day 6 and is recommending to discard it as its very slow growing as they we're both at 4 cells on day 3...
    Thanks for yor reply
    JAN

    ReplyDelete
  4. Anonymous10:28 PM

    am 30 yrs old vegetarian indian going for a ICSI - fet on 13th may 2015. had 22 oocytes with 18 m2 quality and 9 embryos. going to get 3 transferred. endometrium is 7., p4 is 0.28 and estrogen is 22. what would be my success rate? its making me crazy that only 40% is general success rate!

    ReplyDelete
  5. Anonymous8:28 PM



    Anonymous10:28 PM

    am 30 yrs old vegetarian indian going for a ICSI - fet on 13th may 2015. had 22 oocytes with 18 m2 quality and 9 embryos. going to get 3 transferred. endometrium is 7., p4 is 0.28 and estrogen is 22. what would be my success rate? its making me crazy that only 40% is general success rate!


    Same person here., since there is no response here after so long., thought I ll share my scenario so that it may help atleast one person., Had 3 day 3 embryo FET on 13th may., endometrium 10.6. God's blessing 23rd may beta hcg 92.4 and 27 may 493., which translates to Positive pregnancy. So if anyone is scared about success., HEY ITS OKAY AND VERY NORMAL TO BE SCARED., BUT TRY TO BE 100% POSITIVE AND PREPARED FOR ALL CONSEQUENCES., YET LOOKING FORWARD TO THE BABY MIRACLE. FOLLOW UR DR'S ORDERS CROSSING ALL T'S AND DOTTING ALL i's. DO NOT READ NEGATIVE STUFF AT ALL AND PRAY FOR THE BEST POSSIBLE OUTCOME. LOADS OF BABY DUST AND WISHING U UR VERY OWN MIRACLE.... CHAO...

    ReplyDelete
    Replies
    1. Congrats - the 40% turned out to be 100% for you !

      Delete
  6. Sir....you explain all queries beautifully. I love to read the sound knowledge you give about Ivf process in lay language.though my Ivf failed twice but I regained my lost hope after reading your view on frozen blastocysts transfer....dr God bless you always..tks

    ReplyDelete

LinkWithin

Related Posts Plugin for WordPress, Blogger...