An ovarian cyst is usually a collection of fluid or blood within the ovaries. Infrequently, tissue structures like hair, skin or even bone can also be found within an ovarian cyst.
According to Dr Anthony Siow, obstetrician & gynaecologist from Gleneagles Hospital, most fluid and small blood ovarian cysts disappear without treatment, and only a few large ovarian cysts require surgery to prevent them from becoming a threat to one’s health and fertility.
Are all cysts the same?
No, there are many types of cysts that are broadly classified based on what is found within the cyst.
Water or simple cysts – These are cysts that form every month because of ovulation, hence they are termed functional cysts. They are usually detected during an ultrasound screen before the menstrual period. If a pregnancy happens, they get enlarged to support the early phase of the pregnancy. Otherwise, such cysts will disappear after the menstrual period. These cysts usually range between 2 – 3cm, but can grow up to 6 – 7cm and cause a transient pelvic pain.
Blood or chocolate cysts – These are common in women with painful menstruation, or endometriosis. They can also occur with normal ovulation. If the blood cyst is from endometriosis, they tend not to go away and can get bigger with time, causing more pain and reducing fertility. Surgery will be needed when this happens.
It is advisable to keep a close eye on such cysts in older patients as there is a very small risk of progression to cancer.
Solid cysts – These are cysts that contain tissue like hair, skin and bone. They tend to be benign in most cases, and can get larger with time. In a small percentage of solid cysts, there can be immature tissue structures or cancer within. Surgery will then be needed for cyst removal and to confirm the diagnosis.
Apart from classifying ovarian cysts based on its content, a cyst can also be classified as simple or complex based on specific ultrasound features. Simple cysts are usually clear looking while complex cysts have irregular shadows, multiple compartments or abnormal blood flow within.
When is surgery recommended?
Surgery is recommended when the cyst is large (>5cm), causes symptoms like pain, bloatedness, pressure on the bladder or bowel, as wells as contributing to reduced fertility.
For cysts smaller than 4cm, especially those with only water as its content, a wait-and-see approach with a repeat ultrasound in 2 – 3 months is safe. Often such cysts disappear after one to two menstrual periods.
With solid cysts, surgery may be needed as they generally do not go away; and a confirmed diagnosis can only be obtained after surgical removal. Solid cysts can be removed with keyhole surgery if cancer is not suspected from the ultrasound features and blood tests. However, if they are large or have many suspicious and complex ultrasound features, then open surgery to prevent spillage or spread of the cancer cells is advisable.
How common is ovarian cancer?
The lifetime risk of a woman getting ovarian cancer is 1 in 74, or about 1.3%. As this spans a woman’s entire lifetime, the risk increases from very low (<0.3%) in a younger woman to reach 1.3% in older women above 60 years of age. The risk of ovarian cancer is increased if there is a family history of cancer. The risk of ovarian cancer is reduced if a woman has had a few pregnancies, taken birth control pills before, or has had a sterilisation procedure done.
What if I don’t want to undergo surgery?
If you have been diagnosed with a cyst and your doctor recommends surgery and you decline, your doctor will likely monitor your condition every 4 – 6 months.
For water/simple cysts, it is generally alright if surgery is declined as they rarely become cancers.
For blood cyst of endometriosis, there is a 0.4 – 0.6% increased risk of cancer formation. Hence regular ultrasound every 4 – 6 months is advised and surgery needed if there are complex ultrasound features.
For solid cysts, the risk of cancer depends on the ultrasound features. Sometimes, a CT scan or MRI can suggest well-formed tissue like hair, skin and bone within the solid cyst. These cysts are called Dermoid Cysts or Matured Cystic Teratoma and they tend to not become cancerous. However, ultrasounds, CT scans or MRIs cannot confirm if the cyst is benign or cancerous as only surgical removal can provide that information.
Article contributed by Dr Anthony Siow, obstetrician & gynaecologist at Gleneagles Hospital