About the Trial
This page will give you more information about the trial, starting with a video explaining how it will work.
UPDATE: The STOP-OHSS main trial was closed to recruitment in June 2023.
What is our research about?
Ovarian hyperstimulation syndrome (OHSS) is a condition that can affect women having fertility treatment. OHSS is caused by the medication taken to increase egg production during ovulation induction or In Vitro Fertilisation (IVF). If too many eggs develop your ovaries can become large and painful. It can affect women who are still recovering from the effects of the medication given during their fertility treatment and also those who have become pregnant after treatment.
OHSS can range in severity, and can be categorised in the following ways:
Mild OHSS – mild abdominal swelling, discomfort and nausea.
Moderate OHSS – symptoms of mild OHSS, with increased swelling because fluid builds up in the abdomen. This can cause abdominal pain and vomiting.
Severe OHSS – symptoms of moderate OHSS with extreme thirst and dehydration. You may only pass small amounts of urine which is dark in colour and/or you may experience difficulty breathing because of a build-up of fluid in your abdomen. A serious, but rare, complication is a blood clot (thrombosis) forming in the legs or lungs.
Mild symptoms are common and usually resolve quickly, but for some women who experience moderate or severe OHSS these symptoms can worsen. Severe, OHSS can lead to serious health complications needing treatment in hospital for several days or weeks, and in a small number of women can be life threatening.
Currently, fertility teams monitor symptoms of OHSS and intervene if the symptoms get worse and the woman needs to be admitted to hospital for intensive monitoring or treatment. This treatment can include a procedure call paracentesis and is normally performed as an inpatient.
The aim of this trial is to understand whether, taking action earlier by carrying out the same paracentesis procedure but as an outpatient and including additional monitoring can stop symptoms getting worse and prevent women having to be admitted to hospital.
Who is carrying out this research?
This trial is being led by the Sheffield Teaching Hospitals NHS Foundation Trust.
We plan to recruit 224 women with moderate or severe ovarian hyperstimulation syndrome over 3 years. This will take place across approximately 20 fertility units in the UK.
Who is sponsoring and funding the research?
The trial is funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) and sponsored by Sheffield Teaching Hospitals NHS Foundation Trust.
It is organised, managed and coordinated by the University of Sheffield, and data will be be collected and stored by this institution.
Additionally, the trial will be supervised on a regular basis by a Data Monitoring and Ethics Committee (DMEC) and a Trial Steering Committee (TSC). The primary function of the DMEC is to ensure the absolute safety of all participants.
About the procedure
Paracentesis is a procedure where a needle is inserted through the vagina or abdomen to drain the fluid that has collected to relieve the OHSS symptoms and is carried out in a similar way to egg collection. It is generally a safe procedure and will not affect your pregnancy if you are already pregnant. Potential complications include infection and injury to major blood vessels or bowel, but these are extremely rare. In this study the procedure will be performed by your doctor/nurse/radiologist in an outpatient setting to prevent the OHSS symptoms getting worse. It can feel uncomfortable like egg collection, and you will be given pain relief.
What will happen in I take part in the trial?
Women taking part in the trial will be randomly allocated (randomised) to participate in one of two groups:
Group A - the intervention group will have the procedure called paracentesis (drainage of fluid) which will take place in an outpatient setting. They will have extra monitoring from their fertility team which will include filling in a daily patient diary.
Group B - the control group will not have the paracentesis procedure as an outpatient and will be monitored by their fertility team in the usual way, but will be asked to fill in a daily patient diary.
If you decide to take part this means that neither you nor the doctors can decide which treatment you will receive. There is an equal chance of being placed in either treatment group A or B.
What happens to you if you are randomised to the intervention group?
If you are randomised to the intervention group your doctor will perform the paracentesis procedure as an outpatient. The procedure involves putting a thin needle or tube into your abdomen or vagina, depending on how your hospital usually does this, to remove the fluid which has built up. You may be offered a local anaesthetic for this procedure and we will ask you to stay in clinic for a few hours after the procedure to make sure you feel well enough to go home. Depending on how much fluid is in your abdomen, your doctor will drain the fluid then take out the needle or insert a tube which will be attached to a small drainage bag to collect the fluid from your abdomen. The bag can then be attached to your leg and hidden discreetly under a skirt, dress or loose fitting trousers and, your team will explain how to empty it once you get home. It will be taken out when no more fluid is draining which can take about 2 weeks, but your doctor will discuss which is best for you before carrying out the procedure.
We will ask you to fill in a daily diary recording any OHSS symptoms you have. This will include your weight, how much fluid you have been drinking, how much urine you have passed, whether or not you have any pain or breathlessness and we will also ask you to measure your abdominal girth (the width of your tummy). We will give you a tape measure, weighing scales and measuring jug to do this. A member of the clinical team from your hospital will call you and discuss this diary information with you until you have recovered from the OHSS. This will be daily for the first few days at least but may then be less often. Depending on your symptoms you may be asked to visit the hospital for review by your doctor to give a blood sample or to have more fluid drained by the same outpatient paracentesis procedure.
The trial is designed to monitor your symptoms from home and only bring you into the hospital if necessary. For safety reasons we may ask you to visit the hospital weekly, if necessary, during the first 28 days that you are taking part in the trial or if your symptoms start to get worse or have got better, but again this will be discussed with you.
What happens to you if you are randomised to the control group?
Exactly the same will happen as described above but you will not have the paracentesis procedure as an outpatient. However you may be contacted less frequently by the clinical team, in line with the usual care provided at your centre - this may be every few days, but this will be discussed with you. If your doctor decides based on the information you have given during these calls that you need treatment for your OHSS symptoms then you will be admitted to hospital as an inpatient. You might still have paracentesis performed but it will be as an inpatient on the ward and not as an outpatient.
What will happen next if I decide to take part?
If you wish to take part in the trial you will be given a patient information sheet and will be asked to sign a consent form. A member of the Research Team will conduct a screening assessment.
Providing information and data as part of the trial
All women, regardless of which group you are in, will be followed up to see how long it takes for your symptoms to get better and whether hospital admission is needed. We will also compare the safety, acceptability and cost of each treatment. We will ask you to complete questionnaires about your health, how you felt about the service you received and any health care you needed 28 days after you gave consent to take part in the trial. These can be completed by post or online. We will also ask you to complete a daily diary.
You will be contacted by telephone by a research nurse/midwife or DR, or asked to come into hospital for the following reasons:
• A weekly visit (up to 28 days or until your symptoms have got better)
• If your symptoms start to get worse
• Once your symptoms have resolved
During these visits, the doctor/ nurse will ask you some questions about your symptoms. Information will also be collected from your medical notes about your symptoms and details of any time spent in hospital because of OHSS.
If you are taken into hospital during the trial at any other NHS Trust, this information may also be requested from them. We will ask your permission to do this.
We would also like to review your medical notes around 3 months (90 days) after you agree to take part in the trial to collect any information about any infections or blood clots (thrombosis) that you may have experienced. At this point we will also collect any information about whether you are pregnant or any pregnancy outcome. If you are not pregnant we will not collect any further data from your notes. If, however, we find that you are pregnant we will review your notes again around 10 months later (13.5 months after you first joined the trial) to collect information about the outcome of your pregnancy.
The research team will compare how many people were admitted to hospital from both groups at the end of the trial. This will help us to work out whether early paracentesis as an outpatient reduces the chance of women suffering from moderate or severe OHSS being taken into hospital.
What are the possible disadvantages and risks of taking part?
Paracentesis is a relatively safe procedure, but there are some risks, which have been described in the section ‘About the procedure’, and these should be discussed with your doctor/ nurse.
What will happen to the results of the research trial?
The results of this trial will be published in scientific journals and presented at scientific meetings, as well as shared directly with NHS Trusts, professional bodies and patient groups. You will not be identified in any report or publication. If you would like to receive a summary of the trial results a copy of the research report we will send this to you.
Who has reviewed the trial?
Research in the NHS is looked at by an independent group of people called a Research Ethics Committee to protect your interests.