18th Jun, 2012
By Claire O’Sullivan
A fertility clinic in Cork is the first in Ireland to introduce a service which promises a 90%-plus survival rate for frozen embryos, as they will be frozen 600 times faster than before.
The new process, known as vitrification, will improve outcomes for couples who are undergoing intracytoplasmic sperm injection (ICSI) or in vitro fertilisation (IVF).
Generally, as part of the IVF process, several embryos are generated, with one transferred to the womb and the remaining embryos are often frozen.
Vitrification “avoids trauma” to the embryo because of the speed at which freezing takes place compared to traditional, slower, freezing.
The process leads to better quality embryos, which are more likely to lead to a pregnancy.
Already, one woman has become pregnant with twins using vitrification, according to the Waterstone Clinic.
Susan Waterstone of the Waterstone Clinic said the vitrification process was so fast it allowed no time for intracellular ice formation.
“As a result, vitrification avoids trauma to the embryos. In conventional slow freezing, only 70% of embryos survive the freeze-thaw, and those that do survive have less likelihood of generating a pregnancy compared to fresh embryos.
“In contrast, vitrified embryos have a better than 90% freeze-thaw survival rate, and a pregnancy generating potential that is comparable to fresh embryos.”
An embryo is described as the product of human conception after it is implanted in the uterus wall. It remains an embryo until the eighth week of development in the womb, after which it is a foetus.
One of the challenges of modern assisted reproduction is how to minimise the likelihood of twins without compromising the chances of a woman giving birth.
The transfer of two embryos to the womb, increasing the likelihood of one pregnancy, has been the norm in fertility clinics for 25 years, but has a 25% incidence of twins.
However, if, due to age or health reasons a couple would rather a single pregnancy, vitrification is being seen as a good method to increase successes rate without running the risk of a multiple birth.
“Couples who fund their own treatment and are desperate for success are more likely to agree to single embryo transfer if it is supported by a highly successful frozen embryo transfer programme,” said Dr Waterstone.
“The live birth rate of our blastocyst elective single embryo transfer programme for the past three years is 60% per transfer. Vitrification will further encourage more couples to opt for single embryo transfer.”
Vitrification will not raise the cost of IVF treatment at the Waterstone Clinic. IVF at the clinic costs €3,750 and ICSI €4,250.