Overview
Ovarian cysts are fluid-filled sacs that develop on or inside an ovary. Most are functional cysts that form during the menstrual cycle and resolve on their own within a few months. They are extremely common. Pathological cysts (endometriomas, dermoid cysts, cystadenomas) are less common and may require treatment. Rarely, an ovarian cyst can be cancerous.
How common is it?
Functional ovarian cysts are extremely common — most women develop one or more during their lifetime. They are most common in women of reproductive age. After the menopause, new ovarian cysts are less common and require more careful evaluation.
Causes and risk factors
Functional cysts arise from normal follicular development gone slightly wrong. Pathological cysts result from various cell types within or adjacent to the ovary.
Common risk factors
- Follicular cyst: a follicle that fails to release an egg and continues to grow
- Corpus luteum cyst: forms after ovulation when the corpus luteum fills with fluid instead of dissolving
- Endometrioma: ovarian involvement of endometriosis
- Dermoid cyst (teratoma): contains hair, teeth, or sebaceous material — developmental origin
- Cystadenoma: serous or mucinous, arising from epithelial cells
- PCOS causes multiple small ovarian follicles, which are different from the cysts discussed here.
- Ovarian cancer (rare)
Symptoms
- Most small cysts: no symptoms
- Pelvic pain or pressure, typically on one side
- Bloating
- Dyspareunia (pain during sex)
- Irregular periods
- Cyst rupture: sudden severe pelvic pain
- Ovarian torsion (twisted cyst): severe sudden abdominal pain — surgical emergency
When to see a doctor
Sudden severe pelvic pain needs immediate assessment, especially with vomiting or faintness. See a GP for persistent pain or bloating. Cysts found after menopause need a clinician to assess their features and cancer risk; not all require specialist referral or ongoing scans.
Diagnosis
Ultrasound, usually transvaginal when appropriate, assesses cyst size and appearance. Further tests, such as CA-125 or MRI, depend on symptoms, menopausal status and the scan findings. CA-125 alone cannot diagnose or exclude cancer.
Treatments
Watchful waiting
Before menopause, a simple cyst under 5 cm usually needs no treatment or routine follow-up. Larger, symptomatic or complex cysts may need scans or specialist assessment. After menopause, follow-up depends on appearance, size, symptoms and cancer-risk assessment.
Laparoscopic cystectomy
Surgical removal of the cyst wall, preserving the ovary. Used for persisting, large, symptomatic, or pathological cysts. Preferred over oophorectomy in women wishing to preserve fertility.
Drainage
Ultrasound-guided aspiration for simple cysts if surgery is contraindicated. High recurrence rate so rarely used as definitive treatment.
Oophorectomy
Removal of the ovary, used for large complex cysts with high malignancy risk or in post-menopausal women. Laparoscopic approach where possible.
Self-care and lifestyle
- Most functional cysts require no lifestyle change
- Report any sudden severe pain promptly as this may indicate torsion or rupture
- Ensure regular pelvic health reviews if you have PCOS or endometriosis
Prevention
Oral contraceptives reduce the frequency of functional ovarian cyst formation but do not treat existing cysts. No reliable prevention for pathological cysts.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to urgent-care guidance, treatment, diagnosis, risk factors, key facts. This update covers the named sections; a full review of the remaining guide is pending.