Ovarian cysts are small, fluid-filled sacs that can form on or inside the ovaries. They are very common, especially in women of childbearing age. Most cysts are harmless, cause no symptoms, and go away on their own.
What causes ovarian cysts?
- Hormonal changes, especially during the menstrual cycle.
- Endometriosis, when womb tissue grows outside the uterus.
- Pregnancy: a cyst can support early pregnancy.
- Pelvic infections, which can lead to cysts on the ovaries or tubes.
Types of ovarian cysts
| Type | In simple terms |
|---|---|
| Follicle cysts (most common) | Each month an egg grows in a small sac called a follicle, which normally breaks open at ovulation. Sometimes it doesn’t open and keeps growing into a cyst. Usually painless; goes away in 1–3 months. |
| Corpus luteum cysts | After the egg is released, the empty follicle becomes hormone-producing tissue. If it seals up and fills with fluid, it becomes a cyst. Most go away, but some grow, bleed or twist and cause pain. |
| Endometriomas (“chocolate cysts”) | Caused by endometriosis. Filled with old blood; may cause pain during periods or sex. |
| Dermoid cysts | Form from cells that make eggs, so may contain hair, skin or teeth. Often harmless but can grow large and may need removal. |
| Cystadenomas | Grow on the surface of an ovary and may contain watery or thick fluid. Can become large and uncomfortable. |
| Polycystic ovaries | In PCOS, many small cysts form due to hormone imbalance. Not dangerous in themselves, but linked to irregular periods and fertility issues. |
Symptoms
- Bloating or swelling.
- Pressure or pain in the lower belly.
- Sharp or dull aches, especially on one side.
- Pain during sex or periods.
Seek urgent help if you have sudden, severe pain; pain with vomiting or fever; or you feel faint or dizzy.
How are cysts diagnosed?
- Pelvic exam, to feel for swelling.
- Ultrasound, to see the cyst clearly.
- Pregnancy test, to rule out pregnancy.
- Hormone tests, to check hormone levels.
- Blood tests (CA-125), especially after menopause, to check for signs of ovarian cancer.
How are cysts treated?
- Watch and wait: many cysts go away naturally.
- Medication, to balance hormones or reduce cysts.
- Regular monitoring with scans.
- Surgery, if the cyst is large, causing pain, or not going away.
When to see a doctor
- Ongoing lower tummy pain.
- Irregular or painful periods.
- Trouble getting pregnant.
- Severe or sudden pain.
Most ovarian cysts are not dangerous, and many women have them at some point. Knowing the symptoms and types can help you feel more informed and in control. Talk to your healthcare provider if you have any questions or concerns.
This guide is for education and support. It does not replace advice from your own doctor or fertility clinic.