Causes & Treatment

How to Know Which Embryos are Viable

Eloise Edington  |   20 Jul 2021

Embryologists play one of the most important roles during the IVF process. People often wonder what is an embryologist? 

We recently did a brilliant webinar with Laurel Fertility Care – ‘Everything You Need to Know about Embryology’ and we had a ton of questions which we didn’t have time to answer live. That’s why Fertility Help Hub has reached out to LFC’s embryologist, Devin Monahan, to answer the most commonly asked questions concerning IVF and viable embryos.

Read on to hear about the process of deciding which embryos are viable and why it is best to do an embryo transfer for IVF on Day 5 (aka blastocyst stage). 

Words by Laurel Fertility Care

If you’re having fertility treatment with us at Laurel Fertility Care, then you’ll meet our experienced fertility specialists and nursing staff, but our embryologists are always working hard behind the scenes. When they aren’t maintaining the IVF lab, they’re freezing, testing, and monitoring embryos. If you’re going through IVF, you’ll meet them during your egg retrieval procedure.

Our Embryologist, Devin Monahan, has been a part of the Laurel Fertility Care team since 2013 and has contributed to numerous research and review papers, as well as presenting research at several international IVF conferences.

We asked Devin some of your most asked questions about embryology.

Q: I’ve heard that the most “important” piece of the embryo grade is the ICM (1st letter). Do you agree with that?

A: All pieces of the embryo grade are important. At LFC, we don’t find that the ICM grade is any more predictive of favourable IVF outcome than the trophectoderm grade when transferring good or fair quality embryos. However, we prioritise ICM grade when selecting a frozen embryo to transfer (e.g., we would select a 4AB over a 4BA for transfer).

Q: If our embryos are abnormal, would it be bad to try to transfer them or transfer the mosaic one?

A: This is an interesting and controversial topic in our field right now. I would not recommend transferring an aneuploidy embryo. I would recommend transferring a low-mosaic embryo depending on the type of mosaicism (avoid anything with chromosomes 13,18,21,X,Y). Although the scientific literature suggests mosaic embryos have a lower chance of implanting, they still lead to healthy live births. At LFC, we have transferred several mosaic embryos that have led to healthy pregnancies.

Q: Would testing reveal which chromosomes are missing if we continually always get abnormal results?

A: Yes, the genetic testing will show which chromosomes are problematic. It is important to look because if the same chromosomes are causing the abnormality, there could be a translocation present.

Q: Do you think PGT is more important than grade? My doctor told me to ignore the grade since my embryo was PGT normal.

A: The simple answer is yes, PGT is more important, but grade still has predictive value. We find that within normal embryos, good quality embryos have a higher implantation potential than fair or poor-quality embryos. Furthermore, our day 5 embryos appear to do better than day 6 embryos.

Q: If it does not grow past day 3 then is that an egg quality problem or sperm?

A: It’s almost impossible to say why a specific embryo stops growing. There have been some studies that have looked at the chromosomal composition of arrested embryos and found increased genetic abnormalities, so arresting cell division and embryo development may be a way of abnormal embryos shutting down. These genetic abnormalities found in embryos arise from eggs much more often than sperm.

Q: Why do some clinics push embryos past day five to six or seven if five works best?

A: We would never go past day five for a fresh transfer, but if we are going to do an embryo biopsy, we may need to grow them longer. This is so the embryo is big enough, and there are enough cells to safely perform the biopsy. We would not want to compromise the embryo by removing some cells from a small day 5 embryo.

Embryologists are not MDs, but they are highly trained medical professionals, usually holding a master’s degree to the specialised nature of their work. They care for gametes (sperm and eggs) and embryos in vitro.

Key Responsibilities Include:

  • Managing the lab environment
  • Analysing a patient’s fertility
  • Freezing eggs, and/or embryos
  • Embryo creation and Biopsy
  • FET (Frozen Embryo Transfer)
  • Micro-manipulation (this includes ICSI, laser assisted embryo hatching and embryo biopsy)

Related Article – Endometriosis and Infertility – Symptoms, Stages and Treatments by Laurel Fertility Care

Success in fertility care hinges on successful collaboration between fertility doctors, a clinic’s nurses, and the embryologists. You may not spend much face-to-face time with your embryologist team but know that they are working hard in the lab to ensure the healthy development of your embryos.

About LFC: Laurel Fertility Care offers a supportive and knowledgeable team to guide you when you are ready to pursue your dream of a family.  The decision to start a family is life-changing, full of anticipation and dreams.  As the premier boutique clinic in the Bay Area, we are dedicated to helping your family grow, offering a personalised care approach full of hope!

Related Article – Fertility Experts Live – Everything about Endometriosis with Laurel Fertility Care

Hopefully, by answering these questions, you can now better understand the IVF process and the scientific reasoning behind selecting the best embryos for transfer. Knowing that Laurel Fertility Care have contributed to successful pregnancies using mosaic embryos can be especially comforting to hear. It’s clear from their answers that there is a lot of knowledge, selection, and analysis to be done in order to predict the most promising embryos for FET, which is why embryologists are so important to helping people create the family of their dreams. 

If you would like to know more about Laurel Fertility Care and the services they can provide, click here. For more insight into fertility, treatments and clinics, download the FHH App.

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