Ovarian cysts: symptoms, diagnosis and treatment

What are ovarian cysts?

Ovarian cysts are fluid-filled sacs that develop on or inside the ovaries. They are extremely common. Most women will have at least one during their lifetime, often without knowing. The majority are functional cysts, meaning they form as a normal part of the menstrual cycle and disappear on their own within a few months.

Cysts become a concern when they are large (over 5-7cm), cause symptoms, persist beyond two or three menstrual cycles, or have features on ultrasound that need further investigation.

Types of ovarian cyst

Functional cysts

These form during ovulation and are the most common type. A follicular cyst develops when the follicle does not release an egg and continues to grow. A corpus luteum cyst forms when the follicle releases the egg but the sac fills with fluid instead of shrinking. Both types usually resolve within 1-3 months without treatment.

Many small follicles on an ultrasound can also be seen in polycystic ovary syndrome (PCOS), which is a hormonal condition rather than "cysts" in the sense above. If your cycles are irregular or you have other features of PCOS, a dedicated assessment is more appropriate than monitoring a simple functional cyst alone.

Dermoid cysts (teratomas)

These are non-cancerous growths that can contain tissue such as hair, skin, or teeth (the cells are embryological in origin). Dermoid cysts grow slowly and can reach a significant size before causing symptoms. They do not resolve on their own and may need surgical removal if large or symptomatic.

Endometriomas (chocolate cysts)

These form when endometriosis tissue grows on the ovary. The cyst fills with old blood, giving it a dark brown appearance. Endometriomas are a sign of endometriosis and often require both medical and surgical management.

Cystadenomas

These develop from the outer surface of the ovary and can grow quite large. They are usually benign but need monitoring or removal if they cause symptoms or continue to grow.

Symptoms

Many ovarian cysts cause no symptoms at all and are found incidentally during a scan for something else. When symptoms do occur, they may include:

A dull ache or pressure in the lower abdomen, usually on one side. Bloating or a feeling of fullness. Pain during sex. Irregular periods or changes to your usual pattern. Difficulty emptying your bladder fully, if a large cyst is pressing on the bladder. Sharp, sudden pain if a cyst ruptures or twists (torsion). This is a medical emergency and requires immediate hospital attention.

If you have sudden, severe pelvic pain with nausea or vomiting, go to A&E. Ovarian torsion (where the cyst causes the ovary to twist on its blood supply) needs emergency surgery.

Diagnosis

Consultation

Mr Hikmat Naoum, Consultant Gynaecologist (MRCOG), will review your symptoms, medical history, and perform a pelvic examination. If a cyst is suspected, a pelvic ultrasound is the next step and can usually be done the same day.

Pelvic ultrasound

A transvaginal ultrasound is the primary tool for diagnosing ovarian cysts. It shows the size, location, and internal structure of the cyst, which helps determine whether it is a simple fluid-filled cyst (almost always benign) or a complex cyst with solid areas, thick walls, or blood flow that needs further investigation.

The ultrasound is performed at the clinic by Mr Naoum and results are available immediately. Based on the scan findings, he will explain what type of cyst it is and recommend next steps.

Blood tests

If the ultrasound shows features that need further investigation, a CA-125 blood test (£125 including phlebotomy) may be requested. CA-125 is a tumour marker that is sometimes elevated in ovarian cancer, but it can also be raised by benign conditions including endometriosis, fibroids, and menstruation. It is used alongside imaging to build a clinical picture, not as a standalone test.

For women under 40, where ovarian cancer is rare, a CA-125 is usually unnecessary for simple cysts. For women over 40 with complex cysts, it is routinely checked.

Treatment

Treatment depends on the type and size of the cyst, your symptoms, and your age.

Watchful waiting

Most functional cysts resolve on their own. If the ultrasound shows a simple, small cyst (under 5cm) with no concerning features, the standard approach is to rescan in 6-12 weeks to confirm it has gone. No treatment is needed in the meantime.

Medication

The combined oral contraceptive pill can prevent new functional cysts from forming by suppressing ovulation. It does not shrink existing cysts, but it can reduce the chance of recurrence once the current cyst has resolved. For endometriomas, hormonal treatment (pill, Mirena coil, or other progestogens) can slow growth and reduce symptoms.

Surgery

Surgery is recommended when a cyst is large (over 5-7cm), causing significant symptoms, not resolving with observation, or has features on imaging that need histological analysis.

Mr Naoum performs laparoscopic (keyhole) cystectomy, which removes the cyst while preserving the ovary. This is the preferred approach for women of reproductive age who want to preserve their fertility. In some cases (very large cysts, or post-menopause where cancer risk is higher), removal of the entire ovary (oophorectomy) may be recommended.

Surgery is carried out at a private hospital under Mr Naoum's admitting rights. Recovery from laparoscopic cystectomy is typically 1-2 weeks.

Ovarian cysts and fertility

Most ovarian cysts have no impact on fertility. Functional cysts are a sign that ovulation is happening. Endometriomas can affect fertility by damaging ovarian tissue, but treatment (medical or surgical) can improve outcomes.

If you have ovarian cysts and are trying to conceive, or if you are concerned about the effect on your fertility, a fertility assessment alongside your cyst management can give you a clearer picture.

Frequently asked questions