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
- Polycystic ovaries: multiple small follicles in PCOS
- 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
Any sudden severe pelvic pain requires immediate assessment (possible torsion or rupture). See a GP for persistent or recurring pelvic pain, or if an incidental cyst is found. All post-menopausal women with new ovarian cysts need specialist gynaecological evaluation.
Diagnosis
Transvaginal ultrasound is the primary investigation. CA-125 blood test and RMI (risk of malignancy index) to assess cancer risk. MRI for complex cysts. IOTA (International Ovarian Tumour Analysis) criteria guide interpretation.
Treatments
Watchful waiting
Simple, small (under 5cm) functional cysts in premenopausal women are followed up with repeat ultrasound in 3 months. Most resolve spontaneously without intervention.
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.