# Embryo options



## Alibobs (May 27, 2002)

Hi Peter,

Firstly I must say that I think it is fantastic that you take time out to speak to us.

I have a question regarding embryos and the options that are available to us, regarding transfer time.

I believe there are 4 options available:

2 day transfer
3 day transfer
Assisted Hatching
Blastocyst transfer

Is it possible for you to explain for each type of transfer the pro's and con's- bit of a tall order I know  but if you could perhaps let me know how many embryo's are required for each, what % of embryos may be lost for say Blast stage, and in your opinion what has the best overall success rate. Also what is assisted hatching?

Ali


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## peter (Oct 2, 2002)

Dear Ali,

The rule in the UK at present is that patients' recieve a maximum of 2 embryos no matter what stage they are.

At day 2 the embryos are usually between 2 and 6 cell, on average about 95% of fertilised eggs will reach this stage. The overall fertilisation rate of all of the eggs collected is on average between 60-70%

At day three 6-12 cell embryos are transferred

Blastocysts may be transferred on day 4/5 and these are about 120 cells. In many cases only a few embryos will reach blastocyst stagebin the lab and in some cases no embryos reach this stage.

Hatching is a natural process by which the embryo comes out of its' protective covering membrane.
Assisted hatching is when the embryologist cuts a small hole in the membrane surrounding the embryo which is called the zona pellucida. This cut is made either using a very fine needle or in some cases a laser may be used. Once cut the embryo can leave the membrane much easier. Some embryos are thought to be possibly incapable of leaving the membrane themselves and so assisted hatching is offered.

Hope this helps!

Peter



Alibobs said:


> Hi Peter,
> 
> Firstly I must say that I think it is fantastic that you take time out to speak to us.
> 
> ...


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