An embryo transfer is a vital stage of any in-vitro fertilization (IVF) treatment as it is where the fertilised embryo is transplanted into the uterus to hopefully start the pregnancy process.

Here’s what to expect from an embryo transfer if you are planning to undergo IVF and start a family.

What is an embryo transfer?

The embryo transfer is the final part of the IVF process and involves physically implanting a previously artificially fertilized egg into a woman’s womb. The egg is obtained using medication to stimulate the ovaries into releasing its ova, which are removed and then fertilized in a laboratory, using the partner’s sperm or sperm from a donor.

Once a fertilized egg has multiplied into an embryo, it is transferred into the patient’s uterus, where it must successfully attach to the womb wall to start a pregnancy.

Frozen or fresh embryos

When starting IVF, your fertility clinician will discuss the options of a fresh or frozen embryo transfer.

A fresh embryo transfer uses an embryo which has not been frozen but is fertilised after retrieval and implanted into the womb around five days later.

Alternatively, you may choose to opt for or be advised to have a frozen embryo transfer or FET. Human egg freezing after retrieval is now commonplace and can involve the eggs being fertilized before being frozen through cryopreservation, or frozen unfertilized for later use. Frozen embryos are then thawed before the transfer process begins.

How many eggs are transferred?

The number of embryos to be transferred will be agreed with you before the treatment starts and will usually depend on your age.

NHS guidance states that women under 37 in their first IVF cycle should only have a single embryo transfer, although two embryos can be transferred if she reaches the third cycle. Women 37-39 can have a double transfer from their second cycle, while women over 40 can have two embryos transferred from the first.

What to expect from the transfer procedure

Before – once the eggs have been retrieved and fertilized, the doctor will select the best quality eggs to use in the transfer. If several good quality eggs have developed, the surplus embryos that won’t be used in the transfer can be frozen for later use, if needed.

During – the embryo transfer process has been described as being similar to a cervical smear. The clinician will insert a speculum to open up the vaginal wall and, using an ultrasound to guide, they will pass a catheter into the womb. It is through the catheter tube that the embryos are then transferred into the uterus wall.

The whole transfer process should be pretty pain free and local anaesthetic is normally not needed. However, there may be some discomfort from the speculum and patients will need to have full bladder throughout the whole procedure.

After – two weeks after the transfer, a follow-up appointment will be needed to check if the transfer has been successful, and the embryo has implanted.

Potential side-effects

Following the embryo transfer, the recipient may experience some cramping, bloating and discharge which should quickly clear up. The risk of miscarriage as a result of embryo transfer is considered the same as in a natural conception.