In short
An ovarian cyst is a fluid-filled sac on or in an ovary. Most form as part of the normal menstrual cycle, cause no symptoms and disappear within a few months. Simple cysts aren’t linked to ovarian cancer. Sudden, severe pelvic pain with nausea or vomiting can mean a cyst has twisted the ovary or burst, which needs emergency care.
On this page
What is an ovarian cyst?
An ovarian cyst is a fluid-filled sac that forms on or inside an ovary. Cysts are common, most are harmless, and many are found by chance during an ultrasound done for another reason.6
Types of ovarian cyst
- Functional cysts. By far the most common type before menopause. Each month a follicle grows to release an egg. If it doesn’t release the egg, or seals over afterwards, it can fill with fluid. These cysts are part of how the ovary works and usually go away without treatment within a few months6,7
- Dermoid cysts. Benign growths that can contain tissue such as hair or fat. They grow slowly and don’t go away without surgery
- Endometriomas. Cysts filled with old blood, caused by endometriosis
- Cystadenomas. Benign growths from the surface of the ovary that can become large
The many small follicles seen in PCOS are not cysts in this sense, and they don’t behave like them.
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Ovarian cyst symptoms
Most cysts cause no symptoms. Larger ones can cause:6
- A dull ache or pressure low in the abdomen, often on one side
- Bloating or a feeling of fullness
- Pain during sex
- Needing to pass urine more often, or trouble emptying your bowel
- Changes to your periods
When an ovarian cyst is an emergency
Go to an emergency department or call 000 if you have sudden, severe pain low in your abdomen, especially with nausea, vomiting, fever, or feeling faint.
Two things can cause this. A cyst can twist the ovary on its blood supply, which is called torsion. Surgery is needed quickly to untwist it and save the ovary. Or a cyst can burst or bleed. That usually settles with rest and pain relief, but heavy internal bleeding occasionally needs surgery. Ultrasound is the first test for both.4,5
How are ovarian cysts diagnosed?
With a pelvic ultrasound, usually done with a probe placed in the vagina because it gives the clearest picture. The ultrasound shows whether a cyst is “simple” (thin-walled and filled only with clear fluid) or “complex” (containing solid areas, thick walls or internal divisions). Standardised rules help the person reading the scan decide which cysts look benign and which need a closer look.3
A blood test called CA-125 is sometimes added, mainly after menopause. It isn’t a reliable test alone, because many harmless conditions raise it.
Are ovarian cysts cancerous?
Rarely, and almost never before menopause.6 A study of more than 72,000 women who had pelvic ultrasounds found that simple cysts were not associated with any increased risk of ovarian cancer, at any age. Complex cysts and solid masses were associated with a higher risk, which is why they are followed up.1
On that basis, radiology experts now advise that small simple cysts don’t need repeat scans at all, and that larger simple cysts can usually just be checked again after a few months. The aim is less worry and less unnecessary surgery.2
Treatment
- Watchful waiting. The usual approach for simple cysts. A repeat ultrasound checks that the cyst has gone or isn’t growing
- Pain relief while a functional cyst settles
- Surgery. Considered for cysts that are large, persistent, causing symptoms or look complex. It is usually keyhole surgery, and before menopause the surgeon generally removes only the cyst and leaves the ovary6
- Preventing new cysts. If functional cysts keep bleeding or bursting, hormonal treatments that stop ovulation may be offered5
When to see a doctor
- Pelvic pain or pressure that lasts more than a couple of weeks
- Bloating that doesn’t come and go, feeling full quickly, or unexplained weight loss
- Any new cyst found after menopause, so it can be assessed properly
Next step: talk to a doctor
Answer a few quick questions and you’ll get an email about your eligibility. A consultation doesn’t guarantee any particular treatment.
References
- Smith-Bindman R, Poder L, Johnson E, et al. Risk of Malignant Ovarian Cancer Based on Ultrasonography Findings in a Large Unselected Population. JAMA Intern Med. 2019;179(1):71-77.
- Levine D, Patel MD, Suh-Burgmann EJ, et al. Simple Adnexal Cysts: SRU Consensus Conference Update on Follow-up and Reporting. Radiology. 2019;293(2):359-371.
- Timmerman D, Testa AC, Bourne T, et al. Simple ultrasound-based rules for the diagnosis of ovarian cancer. Ultrasound Obstet Gynecol. 2008;31(6):681-90.
- Chang-Patel EJ, Palacios-Helgeson LK, Gould CH. Adnexal torsion: a review of diagnosis and management strategies. Curr Opin Obstet Gynecol. 2022;34(4):196-203.
- Bottomley C, Bourne T. Diagnosis and management of ovarian cyst accidents. Best Pract Res Clin Obstet Gynaecol. 2009;23(5):711-24.
- healthdirect. Ovarian cysts.
- Jean Hailes for Women’s Health. Ovarian cysts.
This guide is general information, not medical advice. It doesn’t replace a consultation with a doctor who knows your history. In an emergency, call 000.