Ovarian Cysts

What is an ovarian cyst, and is it the same as PCOS?

An ovarian cyst is a small sac, usually filled with fluid, that forms in the ovary. Small cysts often cause no symptoms at all and are found by chance during a routine gynaecological examination or ultrasound scan.

The vast majority of cysts found before the menopause are non-cancerous; they are temporary cysts linked to the ovulation cycle that disappear on their own. After the menopause, ovulation stops, so these temporary cysts are not expected; cysts found at this stage are assessed more carefully.

Types of ovarian cyst

• Functional (temporary) cysts: the most common type; they develop as a natural part of the ovulation cycle. When the sac carrying the egg does not burst, a follicular cyst forms; when the "yellow body" left behind after ovulation (corpus luteum) collects fluid, a corpus luteum cyst forms. Most disappear on their own.
• Endometrioma (chocolate cyst): forms when tissue like the lining of the womb settles in the ovary. Because this tissue bleeds every month, a dark brown, thick fluid collects inside the cyst; this is where the name "chocolate cyst" comes from. It is part of endometriosis (a condition in which tissue like the lining of the womb grows outside the womb).
• Dermoid cyst (mature cystic teratoma): a non-cancerous growth arising from stem cells. It may contain different kinds of tissue such as hair, teeth, fat and cartilage.
• Cystadenoma: a non-cancerous growth that develops from the layer covering the outer surface of the ovary. It may contain clear fluid (serous cystadenoma) or thick fluid (mucinous cystadenoma).

Symptoms: often silent

Small cysts often cause no symptoms. As a cyst grows, the following may appear:

• a feeling of fullness or pressure in the lower abdomen,
• pain in the lower abdomen,
• irregular periods,
• pain during sex.

These symptoms can also have other causes; if they continue, they should be assessed.

Emergencies: twisting of the ovary and a burst cyst

• Twisting of the ovary (ovarian torsion): the weight of the cyst makes the ovary twist around the stalk of blood vessels that feeds it. Sudden, severe, doubling-up pain on one side of the lower abdomen or belly, together with nausea and vomiting, is typical. Urgent surgery is needed so that the ovarian tissue does not lose its blood supply and die.
• A burst cyst (cyst rupture): the wall of the cyst tears and its contents empty into the abdomen. This can cause sudden, severe pain and internal bleeding. If the bleeding continues or the general condition worsens, emergency surgery is needed.

Diagnosis: ultrasound and risk classification

The first and most effective method for assessing ovarian cysts is transvaginal ultrasound (an ultrasound scan done through the vagina). On ultrasound, the appearance of the cyst matters as much as its size.

This appearance is assessed with set rules. The "simple rules" of the international IOTA group (rules that separate non-cancerous from cancerous features on ultrasound) and the O-RADS system (risk grading based on the ultrasound appearance) are used for this. Roughly, the logic is:

• Features that suggest a non-cancerous cyst: a cyst with a single chamber, a very small solid area, a structure that casts a shadow behind it on ultrasound (acoustic shadow).
• Features that need attention: irregular solid areas, many small growths rising from the inner wall (papillary structures), fluid collecting in the abdomen (ascites) and high blood flow within the mass.

This classification helps decide which cysts can be monitored and which need further tests or surgery.

The role and limits of the CA-125 blood test

CA-125 is a substance measured in the blood that can rise in some ovarian cancers (a tumour marker). On its own, however, it does not say "there is cancer" or "there is no cancer":

• Before the menopause, CA-125 can also rise in many non-cancerous conditions: endometriosis, fibroids (non-cancerous muscle lumps in the womb), infections in the pelvic area, and even during a period. For this reason, it is not recommended as a routine test before the menopause.
• After the menopause, it is more useful; together with the ultrasound findings, it is one of the main measures used to calculate the risk of cancer.

Monitoring simple cysts: most disappear on their own

A "simple cyst" is a cyst with a single chamber and a thin, smooth wall on ultrasound. The approach that guidelines recommend for these cysts depends on menopausal status.

Before the menopause:

• Simple cysts smaller than 5 cm (50 mm) are usually temporary cysts linked to ovulation; without treatment, they usually disappear on their own within 1–3 menstrual cycles.
• Simple cysts between 5 and 7 cm (50–70 mm) can be monitored with an ultrasound scan once a year.
• For cysts larger than 7 cm that do not go away, surgery is considered (see below).

After the menopause:

• Simple cysts of 3 cm (30 mm) or less that cause no symptoms and are on one side only are considered harmless and do not need routine ultrasound follow-up.
• Simple cysts between 3 and 5 cm can be reassessed after 4–6 months with ultrasound and CA-125.

These limits apply only to cysts with a simple appearance. For cysts that look different, or when there are symptoms, the monitoring plan is set individually.

Diagnosis and follow-up of ovarian cysts are carried out at the practice in Muratpaşa, Antalya.

Does the contraceptive pill dissolve a cyst?

Contrary to a common belief, clinical studies and systematic reviews have shown that the contraceptive pill does not speed up the disappearance of existing functional cysts.

The main role of the contraceptive pill is prevention: because it suppresses ovulation, it is effective in preventing new functional cysts from forming. Whether to use the pill is decided together with the doctor, taking the person's health into account.

When is surgery needed?

Most cysts do not need surgery. According to the guidelines, surgery is considered in the following situations:

• cysts that do not go away (persistent) or that grow during monitoring,
• persistent cysts larger than 7 cm (70 mm),
• suspicious ultrasound findings: solid areas, growths rising from the inner wall, fluid collecting in the abdomen,
• long-lasting, severe pain in the lower abdomen,
• emergencies such as twisting of the ovary or a burst cyst.

Laparoscopic cystectomy and protecting the ovarian reserve

For cysts that look non-cancerous, the first choice is laparoscopic cystectomy (removing the cyst by peeling away its wall during keyhole surgery). In this method, the healthy tissue of the ovary is left in place. For the general features and risks of keyhole surgery, see Laparoscopic (Keyhole) Surgery.

Simply draining the fluid from inside the cyst (aspiration) is not recommended, because the cyst comes back in a high proportion of cases.

The aim of surgery is to remove the cyst while protecting the ovarian reserve (the store of eggs remaining in the ovary). To do this, the cyst wall is gently separated from healthy tissue, healthy ovarian tissue is preserved, and burning the tissue more than necessary to stop bleeding (cauterisation) is avoided.

Chocolate cysts (endometrioma) and getting pregnant

A chocolate cyst is of particular importance for women who want to have children:

• The cyst itself can damage ovarian tissue and lower the ovarian reserve. This reserve can be followed with the blood level of AMH (a hormone that reflects the ovarian reserve).
• When the cyst is removed surgically, healthy ovarian tissue can also be affected, which can lower the AMH level further.
• According to the 2022 endometriosis guideline of the European Society of Human Reproduction and Embryology (ESHRE), routine surgery for a chocolate cyst before IVF solely to increase the chance of pregnancy or live birth is not recommended.
• The decision to operate is made mainly in situations such as severe pain, suspicion of cancer, rapid growth of the cyst, or the cyst making egg collection during IVF difficult.

For this reason, with a chocolate cyst the decision is made individually, taking age, ovarian reserve, symptoms and pregnancy plans into account together.

Ovarian cysts in pregnancy

Most cysts seen on ultrasound in early pregnancy are yellow body cysts (corpus luteum cysts), and by the second three months of pregnancy most of them have shrunk on their own.

• Simple cysts that cause no symptoms can be safely monitored during pregnancy.
• The risk of the ovary twisting is highest with cysts between 6 and 10 cm and in the first three months of pregnancy. Twisting of the ovary is an emergency that needs urgent treatment in pregnancy too.
• If surgery is needed because of severe pain, twisting of the ovary, a burst cyst or suspicion of cancer, the preferred timing and method is usually keyhole surgery in the second three months of pregnancy (second trimester).

Ovarian cysts after the menopause

After the menopause, ovulation stops, so temporary (functional) cysts are not expected. For cysts found at this stage, the main aim is to tell non-cancerous cysts apart from cancerous ones.

For this, a risk of malignancy index (RMI, a cancer risk score) is calculated. The score combines three pieces of information:

• an ultrasound score — based on features such as the cyst having several chambers, containing solid areas, fluid in the abdomen, or both ovaries being affected,
• menopausal status,
• the CA-125 level in the blood.

Cysts with a low risk score (below 200) can be managed by a gynaecologist; suitable simple cysts can be monitored. If the risk score is high (200 or above), a computed tomography (CT) scan of the abdomen and pelvis is done and the patient is referred to a multidisciplinary team that includes gynaecological oncology specialists (specialists in women's cancers).