During an ultrasound you suddenly hear: "there is a cyst on your ovary". That word lands heavily, while most ovarian cysts are benign and disappear on their own. A large share simply arise from your cycle.
I think women hear this far too late. The fright comes first, the explanation only afterwards.
Below you read which types of cyst exist, when complaints do call for investigation, and what blood tests mean in this story. Because that is a smaller role than you probably think.
What is an ovarian cyst?
An ovarian cyst is a fluid-filled sac on or in your ovary. Most arise during your normal cycle: a follicle that does not release an egg, or a corpus luteum that persists. Such functional cysts are benign and usually resolve on their own within a few cycles.
A cyst is therefore not a growth and usually not a disease.
There are also cysts that do not come from your cycle. A chocolate cyst (endometrioma) belongs to endometriosis and is filled with old blood. A dermoid cyst contains tissue such as fat or hair. Those do not disappear on their own.
With PCOS it is different again. The "cysts" on the ultrasound are not real cysts, but many small, immature follicles. Read about that in our pillar PCOS: understanding diagnosis and modern management.
What are the symptoms of an ovarian cyst?
Most ovarian cysts cause no complaints at all and are found by chance. If they do cause complaints, it is usually nagging pain or a pressing feeling on one side of your lower abdomen, a bloated belly, pain during sex or a changing cycle. The pain often sits on one side, and that is a useful detail for your doctor.
A cyst that ruptures or twists gives a very different picture: sudden, severe pain.
The table below helps you tell apart what can be looked at calmly and what cannot wait.
| What you notice | What it can mean | What you do |
|---|---|---|
| Nagging, pressing feeling on one side, varying with your cycle | Fits a functional cyst | Raise it at your next GP appointment |
| Bloated belly, feeling full sooner, needing to urinate more | A larger cyst can press on bladder or bowel | Make an appointment with your GP |
| Pain during sex, always in the same spot | Can fit an endometrioma (chocolate cyst) | Make an appointment with your GP |
| Sudden, severe one-sided pain, nausea, fainting | Possibly a ruptured or twisted cyst | Call your GP or the out-of-hours service straight away |
| Ongoing abdominal complaints with unintended weight loss | Always deserves investigation | Make an appointment soon |
One more thing about weight, because it is searched for a lot. A cyst can make your belly fuller through its own size or through a bloated feeling. Real weight gain across your whole body does not belong to an ordinary cyst.
How do you know if you have an ovarian cyst?
An ovarian cyst is seen on an ultrasound, usually an internal one through the vagina. On it the doctor assesses the size, the contents and the wall of the cyst. Gynaecologists use fixed assessment rules for this, such as the IOTA criteria, which distinguish well between benign and suspicious cysts (Vilendecic, 2023).
Drawing blood is therefore not the first step here.
Often a first ultrasound is simply followed by a repeat scan a few months later. A functional cyst has usually gone by then. If it persists or grows, the gynaecologist looks further.
Imagine the gynaecologist sees a smooth-walled cyst of 4 cm, filled with clear fluid. That picture fits a functional cyst, and a repeat scan in 3 months is then often the whole treatment. If she sees a cyst with septa or an irregular wall, further investigation follows. The picture on the ultrasound drives the decision, not your blood value.
What do blood tests say about a cyst?
Blood tests cannot detect, rule out or assess an ovarian cyst. The tumour marker CA-125 is sometimes drawn for a cyst that looks unclear on ultrasound, but it is regularly raised in benign cysts (Sharma, 2020). As a standalone test outside the consulting room it therefore mainly produces needless worry.
Let me just say it: we do not sell this marker, and that is a deliberate choice.
There is also no population screening for ovarian cancer in the Netherlands. The RIVM runs population screening for breast, cervical and bowel cancer, and ovarian cancer is not among them. That is not an oversight: in a large British study of more than 200,000 women, screening with CA-125 and ultrasound did not reduce ovarian cancer mortality (Menon, 2021).
Where blood tests can help if you have complaints around your cycle:
- Hormones: with an erratic cycle a hormone profile gives insight into what is going on hormonally
- Pregnancy test (hCG): standard with sudden one-sided abdominal pain, to rule out an ectopic pregnancy
- Ferritin and Hb: if you also have heavy periods and feel tired
The Hormones Women panel measures a set of hormones in one draw. That tells you something about your cycle, not about the cyst itself. We keep making that distinction honestly.
Want to know more about the tumour marker that keeps coming up here? Then read CA-125: what this tumour marker does and does not say.
When should you see your GP?
Call straight away with sudden, severe pain on one side of your lower abdomen, certainly with nausea or dizziness. Make a normal appointment for ongoing abdominal pain, a bloated feeling that does not go away, pain during sex or bleeding after menopause. With that last complaint, investigation is always needed.
Your complaints do not have to be dramatic to report them.
In any case, go and see someone for:
- Sudden severe one-sided abdominal pain, with or without nausea
- Abdominal complaints lasting longer than a few weeks
- A belly that gradually becomes fuller without a clear reason
- Bleeding when you are already through menopause
We have written a separate article about that last one, because it always needs investigating: bleeding after menopause.
If you hear during an ultrasound that a cyst was found, ask two things right away: how big is it, and when will it be looked at again. With those two answers you know exactly where you stand.
Frequently asked questions
Are ovarian cysts dangerous?
Most ovarian cysts are benign and disappear on their own, certainly the functional cysts that arise from your cycle. A cyst can rupture or twist, which causes sudden severe pain and needs prompt assessment. If the ultrasound raises doubt, the gynaecologist looks further.
Can an ovarian cyst be detected with a blood test?
No. A cyst is seen on an ultrasound. The tumour marker CA-125 can be raised in benign cysts and says too little on its own. Blood tests are useful here for other questions, such as your hormones, a pregnancy test or your iron values with heavy bleeding.
Does an ovarian cyst give you a bigger belly?
A larger cyst can make your belly feel fuller or press on your bladder and bowels, which gives a bloated feeling. Real weight gain across your whole body does not belong with it. If a fuller belly persists, discuss it with your GP.
References
- Vilendecic Z, et al. Accuracy of IOTA simple rules, IOTA ADNEX model, RMI, and subjective assessment for preoperative adnexal mass evaluation. Gynecologic and Obstetric Investigation, 2023. PMID 36716716.
- Sharma D, Vinocha A. Benign ovarian cysts with raised CA-125 levels. Journal of Laboratory Physicians, 2020. PMID 33390678.
- Menon U, et al. Ovarian cancer population screening and mortality after long-term follow-up in the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS). The Lancet, 2021. PMID 33991479.
- RIVM. Population screening for cancer in the Netherlands. National Institute for Public Health and the Environment. Available via rivm.nl.
- Thuisarts.nl. I have a cyst on my ovary. Dutch College of General Practitioners. Available via thuisarts.nl.
Every blood test result through Lunara includes a professional assessment by a BIG-registered doctor. For the assessment of a cyst, discuss your symptoms with your GP or gynaecologist.
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