Frozen embryo transfer (FET)

What is a frozen embryo transfer?

Frozen embryo transfer (FET) is a procedure in which a previously frozen embryo (fertilised egg) is thawed and placed directly into your womb through a minimally invasive procedure. 

The embryo can be one that you have frozen and stored already, having previously had fertility treatments like in-vitro fertilisation (IVF), or it can be one from a donor. 

We have been advancing fertility care for over 30 years in the Assisted Conception Unit at Guy’s Hospital. Our fertility specialists are internationally recognised as pioneers and treat over 2,000 patients each year. If you’re looking to grow or expand your family with previously frozen embryos, our team can help. 

Why might a frozen embryo transfer be performed? 

Our expert team may advise FET if you’re finding it challenging to become pregnant naturally. Some people may opt for this procedure after unsuccessfully trying to conceive through a fresh IVF transfer.  

FET procedures are generally less invasive and have fewer side effects on your body than other fertility treatments, so it can be a good option for those wanting to avoid long recoveries.  

How is FET done? 

During a FET procedure, we prepare the womb’s lining through medications, potentially increasing your chances of success. This also eliminates the risk of a condition called ovarian hyperstimulation syndrome (OHSS), where your ovaries produce too many eggs and become painful and enlarged. It can also be performed in a natural cycle without medication. The suitability for this would be assessed at a consultation with a doctor. 

A FET may be more suitable if you’re at a higher risk of developing OHSS. 

Who is suitable for FET? 

A FET is an option for single and partnered women, same-sex couples who have stored embryos, and patients that have had pre-implantation genetic testing (PGT) on embryos. Find out more about PGT here.

If the embryos are stored at another clinic, we can facilitate the transfer to our unit.  

Speak with one of our fertility specialists to discuss whether FET may suit you during a comprehensive consultation. They’ll ensure that this fertility treatment suits your unique reproductive needs.

Preparing for a FET 

Before you have your FET, we advise eating well, getting enough sleep and avoiding drinking alcohol and smoking.  

We’ll also provide you with medication to help support and enhance the lining of your womb to elevate your chances of implantation after the FET.   

Generally, a FET procedure is performed once your womb lining is thick enough for implantation. This can be around the time of ovulation (usually midway through your menstrual cycle) or before your period begins.  

We’ll discuss the timeline of your FET beforehand so you can be completely prepared and know what to expect.  

What happens during a FET procedure?  

During a FET procedure, we’ll thaw 1 or 2 of your frozen embryos. We’ll discuss the number to thaw during your initial consultation.  

We do not need to use injections to stimulate your ovaries during a FET. Instead, we provide medication to help prepare your womb and support embryo implantation. 

Once your womb is ready for implantation, which is generally halfway through your menstrual cycle, you’ll attend our hospital for your procedure.  

During the procedure, we’ll perform an ultrasound scan to help us place the embryos where they have the highest chance of implantation. Please attend your appointment with a full bladder to help improve visibility during the ultrasound. 

Your fertility specialist will gently insert a thin, flexible tube (catheter) into your vagina and womb. They’ll place the embryo inside the catheter into your womb. Finally, the catheter will be removed, and the procedure will be complete. 

How long does an FET take? 

A FET procedure takes about 15 minutes to complete. It’s a simple, quick procedure, and you can go home shortly after. 

What happens after a FET? 

After your FET is complete, you may experience watery vaginal discharge or light vaginal bleeding. This outcome does not mean the treatment hasn’t been successful. These common symptoms are a result of the catheter being inserted. You won’t know if the FET has resulted in pregnancy for at least 11 days.  

We’ll also provide you with a date to take a pregnancy test at home. If you have a positive test, we’ll ask you to return 3 weeks later for a scan so that we can check and confirm your pregnancy.  

What is the recovery time for a FET? 

Typically, FET procedures have a very short recovery time. You may experience light vaginal bleeding or watery discharge, but apart from that, you should not have any other side effects.  

Benefits of a FET 

A FET procedure can be a great way for you to grow or start your family when facing fertility challenges. Our expert fertility specialists can perform a frozen embryo transfer (FET) to implant an embryo, with the aim of resulting in a successful pregnancy. 

Other benefits of FET include:

• better implantation rates  
• lower price than other fertility treatments like IVF 
• minimal side effects and downtime 
• multiple attempts to get pregnant, as we’ll only thaw 1 or 2 of your embryos at a time 
• significantly reduces the risk of OHSS  

How successful is a FET procedure? 

We’re selective about the embryos that we freeze, ensuring we give you the best chance possible of becoming pregnant. Generally, 90% of embryos survive the thawing process. 

Despite this, our current clinical pregnancy rate for frozen embryo transfers is 40% – higher than the national average. 

Risks of a FET 

All procedures have potential risks. With a FET, you may have a slightly elevated risk of an ectopic pregnancy (where the embryo implants outside the uterus, usually in your fallopian tubes).  

However, the chances of complications occurring during and after a FET are low and our team will do everything they can to minimise the risks involved. 

Alternative treatments 

If FET does not work for you, you might consider using other fertility treatments such as IVF, intrauterine insemination (IUI) and intra-cytoplasmic sperm injections (ICSI). Our fertility specialists will discuss your options to ensure we meet your needs.