A small number of women who are having treatment to stimulate the ovaries will develop a problem called ovarian hyperstimulation syndrome (OHSS).
Overall, it affects only about 2% of women. Women with a high ovarian reserve are more at risk of developing OHSS (15-20% risk) because their ovaries are likely to respond more vigorously to the ovarian stimulation (FSH) injections. We will tell you if you are in the higher risk group.
What is ovarian hyperstimulation syndrome?
Ovarian hyperstimulation syndrome (OHSS) is a combination of symptoms including enlargement of the ovaries, swelling and discomfort in the abdomen. Often, it is associated with nausea and vomiting. Although we know it is caused by the drugs, we give you to simulate the ovaries, we do not know why only a small number of women develop these problems.
The usual time to start getting problems is a few days after the trigger injection and commonly after egg retrieval.
How do we reduce the risk of OHSS?
The ovarian reserve tests (AMH level and antral follicle count) done before you start your IVF treatment help us identify women at a higher risk of developing OHSS.
For these women, we will use the antagonist protocol to stimulate the ovaries. This is because the antagonist protocol has been shown to reduce OHSS, but it does not remove the risk altogether.
The antagonist protocol
In the antagonist protocol, we will select the appropriate dose of stimulation hormone, to try to reduce the number of follicles (that contain eggs), that your ovaries produce during stimulation. This is not always easy to control, and you can sometimes under-respond to the medication. If this happens, we might stop the treatment cycle and start again on a different dose.
Even with using the antagonist protocol, it is also possible that you still produce a high number of follicles, leaving you still at significant risk of developing OHSS.
Normally, in an IVF cycle, we use a hormone called hCG, to trigger egg maturation, before egg collection. However, hCG has been shown to be the main driver of OHSS. One advantage of the antagonist protocol is the option to use an agonist trigger instead of the hCG trigger.
Using an agonist trigger further reduces the risk of OHSS, but pregnancy rates are lower with the agonist trigger, compared with hCG. This means that if we identify you as being at high risk of developing OHSS and decide to give you an agonist trigger, we will not proceed with a fresh embryo transfer. Instead, we will create the embryos and freeze any suitable embryos for transfer at a later date when the risk of developing OHSS has passed.
If you are following the antagonist protocol and on your final scan, prior to egg collection, you have a large number of follicles (20+ follicles of 11mm size+), you will be prescribed an agonist trigger, usually Buserelin 1mg, with the aim to freeze all suitable embryos and return at a later date for a ‘Frozen Embryo Transfer’ (FET).
To reduce the risk of OHSS, you will also be prescribed additional medication called Cabergoline for one week from the night of your trigger injection. Cabergoline helps to reduce the incidence of OHSS. In addition to Cabergoline, women on the antagonist protocol will be asked to recommence the Cetrotide injections from the evening of egg retrieval and continue them for one week.
Can I develop OHSS on the long protocol?
Yes, because sometimes women respond more vigorously to the FSH injections and develop a larger number of follicles than expected. This can put them at risk of developing OHSS.
If you are on the long protocol and your final scan before egg retrieval shows you have a large number of follicles, (20+ follicles of 11mm+ size) or we collect 20+ eggs at egg retrieval, we will not proceed with a fresh embryo transfer. Instead, we will aim to freeze all suitable embryos and plan a frozen embryo transfer (FET) at a later date when the risk of OHSS has passed.
Unfortunately, not everyone will have suitable embryos to freeze, due to embryo quality, as only good quality embryos will be stored.
To reduce the risk of OHSS, you will also be prescribed additional medication called Cabergoline for one week from the night of your trigger injection. Cabergoline helps to reduce the incidence of OHSS.
If I follow the OHSS risk reduction plan, could I still get OHSS?
Unfortunately, yes. We will use the strategies above to reduce the risk of OHSS but some women will still get symptoms. By not proceeding with a fresh embryo transfer and using medications such as Cabergoline and Cetrotide, (antagonist protocol only) we hope that the symptoms will be milder and resolve quickly.
Can I develop OHSS unexpectedly?
Very rarely some women develop OHSS when they have not been considered at risk i.e. they have a normal ovarian reserve and they did not develop more than 20 follicles/20 eggs. Usually, these women have already had a fresh embryo transfer before any symptoms develop. If this happens, we will monitor you carefully, give you advice, and manage you according to your symptoms.
Can I develop OHSS in a frozen embryo transfer cycle?
A frozen embryo transfer cycle has no risk of OHSS.
How long do OHSS symptoms last?
If you have not had a fresh embryo transfer or you are not pregnant following the embryo transfer, the symptoms will usually resolve when you have your period.
If you are pregnant, you may continue having problems until about the second month of the pregnancy. It will then resolve completely. Occasionally, it can last longer than that.
Does OHSS affect my chances of pregnancy?
Developing OHSS after a fresh embryo transfer will have no effect on your chances of pregnancy.
If I cannot have a fresh embryo transfer will my chance of pregnancy be less when I use my frozen embryo(s)?
Reassuringly, there is no difference in the chance of becoming pregnant if we do not proceed with a fresh embryo transfer and decide instead to freeze your embryos and transfer them at a later date when the risk of OHSS has passed.
What do I do if I feel unwell?
If you are unwell and have any concerns, you can contact the nurses by telephone on 0191 213 8213.
If the clinic is closed, you can contact the gynaecology team on ward 40 at the RVI on 0191 282 5640.
In particular, we need to know if you are concerned about severe abdominal discomfort, start vomiting or are unable to drink anything.
If you do not live close to the clinic, you can still call us for advice and we will advise if you need to see your local doctor.
If you are admitted to your local hospital, please let us know or ask your medical team to contact us.
What treatment is given?
Symptoms of OHSS can often be managed at home with rest, pain killers and staying hydrated.
If you feel very unwell or report that you have worsening symptoms, we may want you to come to the clinic or to the Gynaecology ward for assessment.
A small number of women develop severe symptoms and require hospital admission. Specific treatment depends on your symptoms and may include daily blood tests, an intravenous drip to stop you becoming dehydrated and injections to thin your blood and prevent blood clots.
If you collect a lot of fluid in your abdomen, it may cause you to feel very uncomfortable and under these circumstances, we may drain the fluid away using a fine needle.
How can I help myself?
Please ensure you keep yourself well hydrated by drinking to thirst and are passing a good amount of urine. If your urine is dark in colour, please try to drink some more fluids. If you feel you cannot drink any more or if you are struggling to keep fluids down you should telephone us.
Your appetite might decrease so you might find it easier to eat small meals more frequently instead of 3 main meals.
You should continue to be mobile, moving around gently such as doing some light housework or going for a short walk. You can continue to go to work if you feel able to.
Where can I get further information regarding OHSS?
You can find out more information from the Human Fertilisation and Embryology Authority (HFEA), Royal College of Obstetricians and Gynaecologists (RCOG) and British Fertility Society (BFS).
Some women may be at higher risk of developing OHSS as they have a high ovarian reserve or have had
If you wish to know more about our research, we would be happy to discuss this with you when you come to the clinic.
Contact
If you have any questions or concerns throughout your treatment, you can email the fertility nurses.
We do our best to answer your call as soon as possible, but we are a very busy service, so we may not always have someone available to speak with you immediately. If the line is engaged, please try again later or use the nurse email address above. The telephone line is often quieter in the afternoon.
Outside of these hours, there is an on-call doctor available to speak to in emergencies only on 0191 256 8240. The on-call doctor is not able to change clinic appointments or to answer general queries that are not urgent. These types of calls must be made during clinic opening hours.
For more urgent queries, our telephone line is open 8am to 4.30pm Monday to Friday
Patient feedback
We welcome your opinions and feedback on areas you feel have gone well or suggestions you may have to help us improve our service.
If you have any problems during your treatment or are unhappy with the care you are receiving please contact the Senior Sister (Stacey Turnbull) on 0191 213 8213.
Fertility treatment is sometimes upsetting and frustrating particularly when things do not go quite to plan or you do not get the outcome you had hoped for. Sometimes having a chat with us will help relieve some of the tension and frustrations you may be feeling. We are always willing to listen.
