What Is An Ovarian Cyst ?

Ovarian cysts are fluid-filled sacs¹ that develop on an ovary and usually do not cause any symptoms. The cysts occur naturally and they are quite common in women of all ages. It has been reported that 20% of women develop an ovarian cyst at least once in their lifetime at any age, although they are more common in the reproductive years.²

While most ovarian cysts are asymptomatic and benign, there are cases where they may cause symptoms and require medical treatment.

Overview

Ovarian cysts are known to occur naturally in women of all ages, and they are especially common in women who ovulate³ or women who are pregnant.⁴ Most ovarian cysts are harmless and do not cause symptoms nor require medical treatment. Ovarian cysts can be classed as functional or pathological, depending on how they occur.⁵

Functional, or simple ovarian cysts1, are the most common type of ovarian cysts which usually don’t cause symptoms and resolve themselves naturally in women who undergo a normal menstrual cycle.⁵ In fact, most asymptomatic ovarian cysts are usually found by coincidence during pelvic examinations by a healthcare professional for unrelated health assessments.

Pathological ovarian cysts, also known as complex ovarian cysts,¹ occur as a result of abnormal cell growth and may be harmful.⁶ However, pathological ovarian cysts tend to be rare, occurring more commonly in menopausal women¹ and tend to cause symptoms. Postmenopausal women are generally less likely to develop ovarian cysts; however, if they do they are at a higher risk of developing ovarian cancer.⁷ Unlike asymptomatic functional ovarian cysts, pathological ovarian cysts require medical diagnosis, treatment and follow-up by a healthcare professional.

Causes of ovarian cysts

Functional ovarian cysts

Most ovarian cysts occur naturally during a stage of the menstrual cycle⁸ where an egg is released from one or both of the ovaries. During this stage, a cyst can form when a follicle,⁹ or sac, develops on the fallopian tube but does not rupture to release the egg. These are known as follicular cysts. Corpus luteum cysts are another type of cyst that may develop from the corpus luteum, a cluster of cells that form inside the ovary when the follicle releases an egg.¹⁰

These types of cysts are usually 3 cm in diameter and may grow up to 10 cm in size. Despite the seemingly worrying causes, functional ovarian cysts tend to go away on their own after 2 or 3 menstrual cycles.⁶

 A normal ovary (left) and an ovary with a cyst (right). (Image from InformedHealth.org)⁴

Pathological ovarian cysts

Pathological ovarian cysts are also known as complex ovarian cysts. This rare type of ovarian cyst does not form in relation to the menstrual cycle, but typically forms as a result of abnormal cell growth or underlying health conditions related to the uterus. 

Examples of pathological ovarian cysts include:

• Polycystic ovary syndrome:¹¹ multiple simple cysts grow on the ovaries as a result of a hormonal imbalance.¹² This condition may cause difficulty to conceive a baby
• Endometriomas:¹³ These cysts commonly form in individuals with endometriosis14
• Cystadenomas:¹⁵ These cysts are considered benign cystic tumours and make up to 60% of ovarian tumours¹⁵
• Neoplastic dermoid cysts:⁶ These are also known as teratomas. The rare and benign cysts form from cells that make up the ovary tissue. They may sometimes contain hair or teeth

There are some studies that attribute ovarian cyst formation as a side effect of drug medication. One such study indicated that benign ovarian cysts may develop as a direct result of an immunosuppressant drug called mTORi.¹⁶ Similarly, women on infertility treatment or the breast cancer therapy tamoxifen are at a higher risk of developing ovarian cysts.¹⁷ The development of ovarian cysts is usually monitored in patients undergoing these safe and regulated medicinal therapies.

Signs and symptoms of ovarian cysts

Ovarian cysts occur naturally in women who ovulate and commonly do not cause symptoms, therefore most women who have ovarian cysts do not know they have them. However, ovarian cysts may become a problem if they continue growing and do not go away on their own naturally. Ovarian cysts may cause symptoms as they continue growing in size (more than 10 cm) and/or rupture.⁶ 

In cases of symptomatic ovarian cysts, women may experience one or more of the following:

• Abdominal or pelvic pain - the pain may be sudden and severe when a cyst ruptures
• A bloated abdomen and difficult bowel movements - may be a result of an enlarged cyst pushing against the bowel
• Heavy or irregular periods 
• A frequent need to urinate - may be a result of an enlarged cyst pressing on the bladder
• Difficulty falling pregnant - this is common in women with polycystic ovary syndrome
• Pain during sex
• Nausea and vomiting - an ovarian cyst may cause ovarian torsion,¹⁹ or twisting of the ovary, to cause this symptom

Management and treatment for ovarian cysts

If an ovarian cyst is suspected, a healthcare professional may examine the abdomen and vagina using an ultrasound scan¹⁸ to confirm the presence, type, size and location of thecyst. As in most cases, ovarian cysts go away on their own after 2 or 3 menstrual cycles, and a follow-up ultrasound scan can be used to confirm if the cyst disappears after a few weeks.

Regular ultrasound scans may be ordered in older postmenopausal patients¹ with ovarian cysts who are at a higher risk of developing ovarian cancer according to the American Cancer Society,¹⁹ Furthermore, a healthcare professional may order regular blood tests¹ to screen for cancer proteins that are associated with ovarian cancer.

If symptoms of ovarian cysts are persistently experienced and if there are risk factors for ovarian cancer, a healthcare professional may surgically remove the ovarian cysts²⁰ using keyhole surgery (laparoscopy). 

The birth control pill, or combined oral contraceptives,²¹ are sometimes used to manage functional ovarian cysts by reducing the amount of hormones produced in the ovary during the menstrual cycle in order to prevent ovulation. However, a study on the use of the birth control pill indicated little benefit in reducing ovarian cyst formation.²² Overall, surgical management is the gold standard for managing symptomatic ovarian cysts.

FAQs

How common are ovarian cysts?

It is reported that 20% of women develop an ovarian cyst at least once in their lifetime.²

Who is at risk of ovarian cysts?

Women of all ages can develop an ovarian cyst. However, age is a risk factor for pathological cysts. There is a higher risk of cancerous cysts or ovarian tumours in menopausal and older women.³

What are the complications of ovarian cysts?

Enlarged ovarian cysts may rupture and haemorrhage into the surrounding tissue, causing sudden pelvic pain upon rupturing. Ovarian torsion²⁰ is another rare complication that would require urgent review by a healthcare professional.

How is ovarian cyst diagnosed?

Ovarian cysts are diagnosed by a healthcare professional using an ultrasound scan. Ovarian cysts are common in pregnancy, therefore a pregnancy test may also be performed. Asymptomatic ovarian cysts usually go away on their own without diagnosis nor treatment.

Can I prevent ovarian cysts?

Ovarian cysts occur naturally as part of the normal menstrual cycle, therefore they cannot be prevented.

When should I call my doctor?

A healthcare professional should be consulted if symptoms of ovarian cysts are experienced.

Summary

Ovarian cysts are very common in women who ovulate and they usually resolve themselves within a couple of months. In cases of suspected ovarian cysts, it may be worth taking note of the symptoms and any irregularities in the menstrual cycle, and seek professional medical advice to manage the symptoms.