What is the success rate of IVF and when is PGT appropriate? We’ve asked our Head of embryology 

Hello Lenka, you have been working in the field of embryology for 11 years and at the Prague Fertility Centre for 8 years. What has changed most in embryology during this time?

Embryology is becoming more and more complex, going deeper and deeper and gradually finding solutions to each of the partial causes of infertility. To recap, we used to put sperm and eggs side by side in a petri dish and wait to see if the egg would be fertilised. Today, thanks to a range of modern methods, we can not only maximise the chances of fertilising the egg, but also monitor the embryo’s development in real time, select the best quality embryos, time the embryo transfer correctly and help the embryo to nest.

When I started in the lab years ago, vitrification, a method of freezing cells quickly and safely, was just beginning to be used. Today, it has improved and expanded so much that at PFC we vitrify all eggs and embryos, with a thawing success rate of over 98% for embryos and over 90% for eggs. This increases the chances of couples becoming pregnant, even if fewer eggs are retrieved.

Another significant change that I have noticed is the shift from the earlier focus of assisted reproduction on treating female infertility to the current recognition that about a third of couples struggle with male factor infertility. Thanks to more modern methods of sperm selection, we are now able to help a significant percentage of couples with male factor infertility. At the Prague Fertility Centre, we use the latest Microfluidic Chip Sperm Selection (MICHSS) method, which has replaced the MACS method used previously. In contrast to traditional methods of sperm selection by centrifugation and subsequent monitoring of sperm motility, MICHSS reduces sample handling time from approximately 2 hours to only 30 minutes. Sperm are therefore exposed to the external environment for a shorter period of time, reducing the risk of DNA fragmentation and mechanical damage. This is critical as studies show that sperm DNA fragmentation leads to a lower likelihood of proper embryo division and consequently a lower implantation success rate.

At PFC, we have also introduced an innovative polarisation microscopy method, OptimFert, which allows us to determine the degree of maturation and the most appropriate time to fertilize the oocyte by ICSI.

Finally, IVF is no longer just about treating infertility, but also about helping fertile couples who have a genetic burden in their family and want to avoid passing it on to their offspring. Increasingly, we are also helping women and men to preserve their fertility through the preventive freezing of eggs or sperm.

What is the role of the embryologist in the IVF process? How does the doctor work with the embryologist? Who decides which embryo to transfer?

To put it simply, the doctor takes care of the couple and we take care of their precious cells and embryos. So the doctor’s job is to prepare the woman for the egg retrieval process so that we can have the best possible outcome, but with minimal risk to her. At the same time, she prepares the lining of the womb so that the embryo has the best possible conditions for implantation and development. Our aim in the laboratory is to obtain the best possible quality of viable embryo. It’s not just about a positive pregnancy test, it’s about a successful pregnancy and the birth of a healthy baby. This can be achieved by selecting the best developing embryo (today, for example, thanks to time-lapse monitoring) or by pre-implantation diagnostics.

What percentage of cycles are successful?

This depends on the age and type of cycle. For donor egg cycles, which we specialise in at PFC thanks to our own donor programme, we achieve a success rate of around 70% per cycle. For egg donation cycles, the success rate depends very much on the age of the patient. According to our statistics from the first half of 2002, 53% of embryo transfers resulted in a positive pregnancy test for patients under 35, while the success rate was slightly lower (47%) for patients in the 35 – 40 age group. The percentage then drops rapidly in women over 40. For this reason, preimplantation genetic diagnosis (PGD) is increasingly being chosen for patients over 35, as it significantly increases the pregnancy success rate to 70% and also significantly reduces the miscarriage rate by selecting genetically healthy embryos.

So would you recommend PGT‑A screening to all couples?

In general, almost no advanced laboratory method, except perhaps ICSI, which I consider to be the standard today, is universally recommended, but on a case-by-case basis. In addition, preimplantation genetic screening of the embryo is more expensive and time-consuming, so it is important that the couple meet some of the Genetics Society’s recommendations for its use.

These include age over 35, poor sperm count, repeated failed IVF cycles, family history of genetic disease or repeated miscarriages. It is also important to mention that a condition for using PGT‑A is to obtain at least one embryo at the blastocyst stage (i.e. a five-day-old embryo).

Thank you very much for your answers. Last question: ​“What makes an embryologist a great embryologist?”

Experience, empathy, a laboratory background with innovative technologies that he is willing to keep learning about, and above all, a team. Although it doesn’t seem like it, embryology is very much about collaboration, both within the laboratory team and in close cooperation with doctors. And that’s what I really like about working at PFC. The fact that we have a large team of eleven, but at the same time a very stable team that has kept us together over the years. At the same time, we’re on the same page with our top doctors, who respect each other and look for individual solutions for each couple.