An ovarian cyst is a fluid-filled sac in or on the ovary. It is a fairly common condition, mainly seen in girls and women of childbearing age. The vast majority of cysts are benign and disappear on their own. A small cyst almost never causes complaints. Larger cysts can cause vague abdominal pain, pelvic pain, or problems with menstruation. Certain conditions increase the risk of ovarian cyst formation. The ovaries (ovaries) are located in the woman’s abdomen, to the left and right of the uterus. They are almond shaped, have a length of 2 to 4 cm and a width of 1.5 to 2 cm. The dimensions mainly depend on the age of the woman; a woman aged 25 to 30 has the largest ovaries. The ovaries contain follicles (egg sacs), in which the eggs grow and mature. In fertile women, a mature egg is released once a month at ovulation. This egg is transported via the fallopian tube to the uterus, where it can possibly be fertilized by a sperm cell. An unfertilized egg is removed from the body during menstruation, together with blood and uterine lining. The ovaries also produce various (female) hormones, including estrogen and progesterone, which influence the menstrual cycle.
An ovarian cyst, or cyst of the ovary, is a cavity in the ovary that contains fluid. This usually causes the ovary to be larger than normal. The fluid in the cyst varies from clear, thin and watery to cloudy, thick and syrupy. The sizes of the cyst vary from a small bean to a large melon. Both the type of fluid and the dimensions depend on the type of cyst. An ovarian cyst is almost always benign. A malignant cyst, which causes ovarian cancer, is very rare and is mainly seen in women over 40 years of age.
Follicle cyst: the most common cyst in the ovary
A benign follicle cyst with a diameter of 4.5 cm / Source: Ed Uthman, Wikimedia Commons (Public domain)
A so-called follicle cyst or functional cyst is by far the most common. Around ovulation, there is a small, fluid-filled space in the ovary (the follicle), containing the egg. Normally the follicle bursts open when the egg is ripe, so that the egg can be transported to the fallopian tube. The follicle then shrivels. However, sometimes the follicle does not burst and continues to grow due to fluid retention. In that case we speak of a follicle cyst. A follicle cyst mainly occurs in young women, but is also no exception in menopausal women. The cysts can be about 7 centimeters in diameter. Usually only one cyst is present in one ovary. However, the cysts can also occur in groups and in both ovaries. Generally, a follicle cyst will disappear on its own within a few months, although it can sometimes return during each cycle. Occasionally, malignant cells develop in a follicle cyst over time.
Less common cysts in or on the ovary
Unlike most ovarian cysts, a cystadenoma arises from cells lining the outside of the ovary. The cyst is usually connected to the ovary by a stalk and, because it lies freely in the abdominal cavity, it can become very large. The cystadenoma may be filled with a thin fluid (serous cystadenoma) or a thick, mucinous to viscous fluid (mucinous cystadenoma). These types of cysts generally do not disappear on their own, but in the vast majority of cases they remain benign. A cystadenoma is more common in women over 40 years of age.
After a mature egg has emerged from the follicle (egg sac in the ovary), the follicle turns into the corpus luteum (yellow body). If the egg is fertilized, the yellow body produces hormones (progesterone) that help with pregnancy . If the egg remains unfertilized, the corpus luteum shrinks and is rejected. Sometimes, however, the latter does not happen and the corpus luteum persists. It can then fill with fluid or blood. This is called a corpus luteum cyst . A corpus luteum cyst can grow to about 6 centimeters in size, but usually disappears on its own within a few months.
A dermoid cyst (7 by 4 cm) with mature teeth, skin and hair / Source: Billie Owens, Wikimedia Commons (CC BY-SA-3.0)
A special cyst is the so-called dermoid cyst or miracle tumor. This cyst develops from the cells that produce the eggs in the ovary. An egg must eventually develop into all possible cell types. A dermoid cyst can therefore contain ‘foreign’ objects, such as hair, skin, teeth and bones. These types of cysts can grow very large (up to 15 centimeters in diameter). In approximately 10% of cases, a dermoid cyst occurs in both ovaries. A dermoid cyst is and almost always remains benign and in half of people the cyst disappears on its own within a few months. Dermoid cysts are relatively common in women younger than 30.
In addition to the above-mentioned ovarian cysts, there are a few (very) rare types of cysts in the ovary.
Increased risk of developing ovarian cysts
Certain conditions increase the risk of developing ovarian cysts. In Polycystic Ovary Syndrome (PCOS), the balance between the different hormones produced by the ovaries is altered. Polycystic means multiple cysts. Women suffering from PCOS have a greatly increased risk of developing many small, benign ovarian cysts. Because in PCOS the eggs do not grow or grow irregularly and therefore no or very irregular ovulation occurs, this condition also causes problems with menstruation (irregular, very light or no menstruation) and fertility. PCOS is one of the leading causes of infertility. In addition, too much testosterone (male hormone) often causes excessive hair growth on the face, abdomen and chest, less hair on the head and acne. Many women with PCOS also suffer from obesity. The condition is common; it is estimated that ten to fifteen percent of folds have PCOS. The cause is not exactly known. Insulin resistance and hereditary factors probably play a role. PCOS cannot be cured. The symptoms can (partly) be treated.
A ruptured chocolate cyst in the left ovary / Source: Hic et nunc, Wikimedia Commons (Public domain)
In endometriosis, the mucous membrane that lines the inside of the uterus has spread to places outside the uterus (for example in the lower part of the abdominal cavity or in the ovaries). The uterine lining renews itself during each cycle, so that any fertilized egg can nestle in it. If fertilization has not taken place, the mucous membrane, together with blood, is removed from the body during menstruation. The endometriosis spots respond to the hormonal cycle, which can cause them to bleed during menstruation. Women who suffer from endometriosis have a greater chance of developing one or more cysts on the ovaries. These cysts usually contain old blood, which resembles chocolate. The cysts are therefore also called chocolate cysts. ‘Endometriosis cysts’ are and almost always remain benign. The endometriosis spots (mucous membrane spots) can disappear on their own over time, but sometimes they settle deeper in the underlying tissue. In that case, severe, often long-lasting, pain in the lower abdomen occurs and menstruation in particular becomes very painful. Endometriosis must be treated because the condition (in addition to the symptoms it causes) can lead to infertility.
Complaints due to ovarian cysts
Small cysts usually do not cause any complaints. Larger cysts can cause vague abdominal pain and a dull ache in the pelvis (usually on one side) or pain during intercourse. With a corpus luteum cyst, the normal functioning of the corpus luteum can be disrupted, causing menstruation to become irregular or absent. Lighter or heavier menstruation or vaginal bleeding after menopause can also be caused by certain cysts. Large cysts can put pressure on adjacent organs, such as the rectum or bladder, causing urinary problems or constipation. Sometimes cysts grow so large that the abdomen becomes thicker.
The complaints become more severe when bleeding occurs in the cyst, the cyst bursts and the contents end up in the abdominal cavity or when the cyst rotates on its axis. The ovary itself can also rotate when it is very enlarged due to the cyst. This reduces the blood supply. Such complications cause acute, severe and stabbing abdominal pain, which is sometimes accompanied by nausea and fever. Emergency surgery is then necessary.
Diagnosis and treatment of ovarian cysts
Based on the complaints and medical history, the GP or gynecologist will perform an internal examination. An enlarged ovary or a cyst on the outside of the ovary can usually be felt quite clearly. If an abnormality is found, an additional ultrasound will be performed. This allows the size of the cyst and the number of cysts to be determined. The type of cyst is also usually clear with an ultrasound. The cyst can also be punctured (punctured) to examine the contents (fluid). If the ultrasound scan is inconclusive or if there is suspicion of a malignant abnormality, a CT scan of the abdomen and small pelvis or a laparoscopy (keyhole surgery of the abdomen) is performed.
In principle, small, benign cysts do not need to be treated. In that case, regular check-ups by the gynecologist are usually advised. If there is any doubt about the type of cyst or if the cyst is larger than 7 cm in diameter, the cyst is surgically removed. In women over 50 years of age, smaller cysts are sometimes also removed, because the risk of a malignant change is somewhat greater. A dermoid cyst is always removed because of the complications it can cause. Sometimes the ovary affected by the cyst is also removed. Malignant cysts are removed together with the relevant ovary and fallopian tube.