How to improve IVF pregnancy rates by blastocyst vitrification. A guide from Malpani Infertility Clinic , Mumbai, India

1. Effect of Artificial Blastocyst collapsing Before Vitrification
Dr. Sai, Chief Embryologist, Malpani infertility Clinic Pvt. Ltd.
What is a blastocyst?
Blastocyst is the stage of you Embryo on Day 5/6. At this stage the embryo will have more than 100 cells.
We can transfer embryos on day 2, day 3 or day 5; and then freeze the rest. We at MICPL, prefer to
freeze embryos on day 5/6 at blastocyst stage, as survival rate and implantation rate is better as
compared to day 2 or day 3.
Vitrification is a fast freeze process – the embryo undergoes instantaneous ‘glass-like’
solidification without the damaging formation of ice crystals (which can occur with the standard
method of slow freezing).
Blastocysts are very sensitive, and they usually collapse temporarily ( because the fluid in the
cavity is lost) when are handled with a pipette ( taken in and out of the pipette 3-4 times) or
treated with a laser beam (a laser beam is shot at the trophectoderm (trophoblast).
Intact blastocyst collapsed Blastocyst

2. When we vitrify your embryos on Day 5/6 (Blastocyst), in the process they usually shrink (the
inter cellular fluid in the cavity leaks out) and then re-expand and again shrink before we
actually load them cryolock (straw) and store them in Liquid Nitrogen.
When we thaw them, blastocyst embryos take time to re-expand completely to their original
size.
At MICPL, as show in the above images, when we thaw blastocysts they usually recover ( which
means they expand) when they are being thawed, after being placed in the series of thawing
solutions. Once blastocysts are transferred to culture medium for incubation, they shrink and
then they take some time to re-expand (usually 4 hours).

3. This time for re-expansion can be reduced 2 hours by adding another step to the vitrification
(freezing) protocol. If we artificially collapse blastocyst before we vitrify them can dramatically
reduce recovery (re-expansion time) after we thaw them.
Artificial collapsing of blastocyst can be induced using 2 techniques.
1) Puncturing blastocyst using an injection pipette.
2) Using Laser shot to induce collapsing.

4. The blastocyst collapses within 30 sec post laser shot or puncturing using pipette. After the
blastocyst collapses, we can vitrify them using the standard Blastocyst vitrification protocol.
This pretreatment of blastocyst pre vitrification ( by artificially collapsing them) helps them
recover more quickly (within 2 hours ) after thawing them.