What Do Embryologists Do in IVF?

An embryologist helps to increase your odds of getting and staying pregnant.
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Consider an embryologist to be a well-trained matchmaker for couples who use in vitro fertilization, or IVF, to conceive. Embryologists introduce one or more sperm to one or more eggs and watch as the cells multiply and then multiply some more. They also help select the embryo or embryos that will most likely result in a healthy pregnancy and help the doctor during the transfer process. Your embryologist may even give you a sonogram picture of the multi-celled embryo that will one day become your son or daughter.

Understanding IVF

IVF is a common way that couples dealing with infertility issues can conceive a child. A doctor retrieves eggs and collects a sperm sample, fertilization occurs in a laboratory outside the body and any resulting embryo is transferred back into the body three or five days later. Your embryologist, often working behind the scenes, makes sure that your doctor transfers back to you the healthiest embryo with the highest odds of resulting in a pregnancy.

Sperm Testing

Your embryologist will test a sample of the sperm you plan to use. The embryologist will determine if the sperm is healthy enough to fertilize the egg on their own, or if she needs to help the sperm by injecting it right into the egg. If she determines that the sperm may need some help fertilizing an egg, she will likely wash and prepare it first before fertilization. Most fertility clinics will test sperm in advance of the egg retrieval and then ask for a fresh sample on the day the doctor retrieves your eggs.

Egg Retrieval

After your doctor retrieves your eggs, your embryologist’s real work begins. She receives test tubes filled with fluid that your doctor took from your ovaries. Inside this fluid are your eggs. Your embryologist will examine the fluid, identity and extract the eggs from the fluid and place the eggs in separate petri dishes, where they’ll remain for the rest of the process. Egg retrieval is an outpatient procedure. Before you go home, your embryologist or doctor will tell you how many eggs were retrieved.


Hours after your doctor retrieves your eggs, your embryologist attempts to fertilize them. Depending on the health of the sperm, she may be able to place sperm inside each petri dish and let the sperm fertilize the egg on their own. If testing proved that the sperm will need help to fertilize an egg, she will inject a sperm into each egg.

Embryo Testing

The day after the retrieval, your embryologist examines each egg and checks for signs of fertilization. She will place all of the fertilized eggs, or zygotes, into a temperature-regulated incubator. If the zygotes divide and multiply as normal, they become embryos. Three days after the retrieval and fertilization, your embryologist will test the embryos for genetic markers. During this process, she also will determine the quality of the embryos. She often bases the quality of an embryo on how many cells it has three days after fertilization. After deciding which embryos are most likely to implant and result in a healthy pregnancy, your embryologist will place them inside transfer catheters.

Embryo Transfer

Your doctor and embryologist will let you know if the transfer will take place at day three or day five. Before the transfer, your doctor and embryologist will talk to you about how many embryos you have and how many you want transferred. Most fertility clinics recommend transferring one at a time. Your doctor will insert the transfer catheter inside you and place the embryo at the top of your uterine cavity.


Your embryologist can cryopreserve any embryos that she believes will result in a healthy pregnancy. During cryopreservation, your embryos are frozen in their current state. When you decide you’re ready to try to get pregnant again, you can use one or more of your cryopreserved embryos rather than start the IVF process over.

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