Ovarian Cyst: Types, Causes, Symptoms, and Treatment

What is an ovarian cyst?

An ovarian cyst is a sac filled with fluid that forms on or inside an ovary. This is an activity which normally occurs during the menstrual cycle, and such cysts will form and go away. However, in some cases where the cysts continue to grow, they sometimes become cancerous. Cysts can be extremely painful, especially in period pain, sharp or irregular pain in the leg or abdomen. It can be grinding and severe or cause discomfort in the cervix. Cysts come in different shapes and sizes. For example, a follicular cyst, which is the most common type, results from the growth of a follicle. A corpus luteum cyst forms when in the final stage of releasing an egg, and a dermoid cyst forms from cells that make eggs. Other types of cysts include endometrial, haemorrhagic, and cystadenomas.

Ovarian cyst symptoms

Abdominal or pelvic pain can be a symptom of an ovarian cyst. The pain can be caused by the cyst’s size, pressure from surrounding organs, or its rupture. The severity of the pain can range from mild to severe. If the cyst is in the early stages of formation, it may cause a dull, non-specific ache. However, if the cyst grows larger in size, the pain can become more severe as the cyst pushes against the surrounding organs. If the cyst ruptures, the sudden acute pain on one side of the lower abdomen may be an indication of hemorrhage or significant irritation to the peritoneum. This is an emergency situation, and you should seek medical care if these symptoms occur. Another cause of severe pain occurs if the cyst causes the ovary to twist on itself (torsion). This prevents the blood supply from getting to the ovary and can be very painful. This is also an emergency situation. More than half of the women who have a cyst experience pain in the lower part of their abdomen. Usually, it occurs about two weeks before your period is due and then goes away a few days after it starts. This is due to the hormones involved in your menstrual cycle and the cyst’s response to these hormonal changes.

What causes ovarian cysts?

Cysts caused by ovulation

Another type of cyst that is related to the menstrual cycle is a cyst that forms on what is known as the corpus luteum. The corpus luteum is what is left of the follicle after the egg has been released. The purpose of the corpus luteum is to produce hormones that are needed to conceive. If pregnancy does not occur, the corpus luteum disintegrates. If the corpus luteum fills with blood, it can cause a cyst to form and the cyst can become very large and cause pain. This is known as a haemorrhagic cyst, and these types of cysts can sometimes twist the ovary and cause severe pain. Haemorrhagic cysts can be diagnosed with an ultrasound, and symptoms are monitored. They often resolve themselves within a few months without the need for further intervention.

Cysts caused by ovulation are the most common ovarian cysts. These cysts form when the follicle that releases an egg does not do so, and the follicle swells with fluid. This type of cyst can range in size and normally affects women during their childbearing years. Normally, these cysts cause no pain and appear and disappear without the woman ever knowing that she had them. In other instances, there may be minimal symptoms such as a dull ache or pain, or the cyst can cause the feeling of being bloated when the swelling becomes severe. When this type of cyst is diagnosed, a woman is told that she has an unruptured follicle, which is another way of describing the type of cyst. This diagnosis may cause concern, but an unruptured follicle will resolve itself without intervention and there will be no long-term implications.

Cysts caused by other medical conditions

The most common site of cysts caused by other medical conditions is on the surface of the ovaries. The cysts can be numerous and quite varied in size. This type of cysts are often the result of a condition called polycystic ovary syndrome (PCOS). This is a hormonal disorder which causes many small fluid-filled sacs to form in the ovaries. Each sac is actually an undeveloped follicle in which the egg matures. However, due to the hormone imbalance in PCOS, this process is interrupted and ovulation does not occur. Instead, the follicles remain as cysts on the ovaries. PCOS is a very common condition in women of reproductive age and affects approximately 4-7% of the population.

Exactly the same as functional ovarian cysts, cysts caused by other medical conditions may be located on the inside or on the surface of the ovaries. Each type can cause a lot of pain and may or may not produce symptoms. However, there is one thing that sets them apart. They are the result of an independent underlying condition, a non-ovarian problem that has resulted in the development of the cysts on the ovaries.

Cysts caused by abnormally growing cells

Another type of cyst, which can form after the egg has been released, is a corpus luteum cyst. A cyst develops in this case when the sac does not degenerate and fluid accumulates, causing the sac to swell. This type of cyst can grow to become 4 inches in diameter and cause pain or bleeding in the uterus. This cyst can resolve on its own in a few weeks; however, it may grow and cause hemorrhage into the cyst and affect twist or cause torsion of the ovary. This may require surgical intervention. Sometimes during this process, a follicle may fail to release an egg and continue to grow to become a cyst. This type of cyst is known as a follicular cyst and is a simple cyst. This cyst can grow to become 2.5 inches in diameter and usually does not cause any pain, disappearing after a few periods. This cyst forms when the LH surge fails to trigger ovulation, and the hormone FSH continues to stimulate the follicle.

The growth of a functional cyst involves normal cell division. This is what exactly causes the mishap? In the normal ovary, a follicle is a fluid-filled sac that contains an egg. Follicles develop each month in the normal ovary. Usually, several follicles begin to develop, however, the one that will ovulate is the dominant follicle, which continues to grow while the others degenerate. The dominant follicle is surrounded by cells that secrete estrogen, and when the egg is mature, the follicle ruptures and releases the egg. The empty sac of the dominant follicle then becomes a corpus luteum which secretes large amounts of progesterone to prepare the uterus for possible pregnancy. If pregnancy does not occur, the corpus luteum degenerates, causing a drop in levels of progesterone and estrogen. At this point, the beginning of the next menstrual cycle begins. This is the typical process each month in the normal ovary.

Types of ovarian cysts

Functional ovarian cysts

Ovarian cysts are fluid-filled sacs or pockets within or on the surface of an ovary. Most women will develop at least one cyst at some point in their lives. Ovarian cysts are very common in women with regular periods. A cyst is a general term used to describe a fluid-filled structure. Ovarian cysts are one of the most common causes of pelvic pain in premenopausal women and one of the most frequent causes of gynecologic surgical procedures. The US Food and Drug Administration (FDA) has recently advised that a common type of ovarian cysts known as ovarian cysts should be diagnosed within the « cyst population » in postmenopausal women, in order to rule out the possibility of ovarian cancer.

Definition

A functional ovarian cyst is a sac that forms on the surface of a woman’s ovary during or after ovulation. It holds a maturing egg. At the time of ovulation, the egg is released from the sac (known as the follicle or « egg sac ») and the sac will dissolve. In certain cases, the sac may not dissolve and remain on the ovary. This type of functional ovarian cyst, known as a follicular cyst, usually results from a pregnancy hormone being released.

Symptoms and effect on fertility

Most functional ovarian cysts do not cause any symptoms. They are usually discovered during a routine pelvic examination. Cysts that do cause symptoms may produce an aching pain in the abdomen on the side of the cyst. This pain may be due to the cyst becoming large, bleeding, bursting (rupture), twisting (torsion) or putting pressure on surrounding organs. Cysts that bleed or rupture may result in sudden and severe pain. This may require treatment and should be consulted with a doctor. Ovarian cysts found in women of childbearing age may be associated with an increased risk of infertility. This is due to the scarring left on the ovary from the cyst, or from the cyst itself hindering the process of ovulation.Another type of functional ovarian cyst is a corpus luteum cyst which forms if the sac does dissolve, but seals back up and accumulates fluid inside. This type of cyst will usually dissolve on its own within a few weeks. Both types of cysts produce hormones and usually do not cause any symptoms.

Treatment

Observation may be the only required treatment for an asymptomatic ovarian cyst. This is especially so for postmenopausal women. In women of childbearing age, who are premenopausal, observation is reasonable for 6-8 weeks for a small cyst. This is to assess if the cyst will resolve on its own as some cysts will go away after 1-2 menstrual cycles. Further steps include use of hormonal contraceptives (the combined pill, patch, or vaginal ring) which may reduce the risk of new cysts developing. Using the progestogen only pill (mini-pill) is also an option. This is said to decrease the risk of functional ovarian cysts. If the cyst is large, persists or causes symptoms then surgical intervention may be required. This is necessary if the cyst has any chance of being an ovarian cancer. It is notable here that functional ovarian cysts are the only type of ovarian cysts that hold a possibility of being ovarian cancer.

Dermoid cysts (sometimes called benign mature cystic teratomas)

Dermoid cysts are a kind of mature cystic teratoma. This type can be very interesting because it can contain other tissues rather than just fluid. It could contain sebum (a fatty oil substance from the skin), hair, cartilage. Dermoid cysts develop from the same cells that eggs are made from, so they are only diagnosed in women.  They can be found by chance when looking for another problem, as they do not show many symptoms and are rare. If a dermoid cyst is found and it is small and not causing any problems, it can be left unless there is a concern about cancer. If removed, it should be done by a specialist called a gynecologic oncologist as it is most commonly found on the ovaries and can be hard to remove. Usually only the cyst is removed and there are rarely any complications. It is worth the removal of the cyst as there have been rare cases where the material inside has caused a shock-like pain if released into the ovary. Although it is rare, dermoid cysts have a chance to become cancerous, usually in postmenopausal women.

Cystadenomas

Cystadenomas are a growth that spreads from the surface of the ovary and unlike functional cysts, which develop as part of the menstrual cycle, are tumors. They are named depending on the type of cells that are inside the cyst and are usually filled with watery liquid. Cystadenomas are formed from cells on the outer surface of the ovary and for this reason there are two types, serous cystadenomas and mucinous cystadenomas. Serous cystadenomas are filled with a thin, watery liquid and are usually benign, only 15% are malignant. Mucinous cystadenomas are filled with a thick, mucousy liquid and are 80% of the time, malignant. Women that are perimenopausal are more likely to develop a malignant form of the cyst. Both types of cystadenomas have symptoms which are similar to those of functional cysts and can be diagnosed using an ultrasound or CA125 blood test. If the cyst is large or is causing symptoms the usual recommended treatment is to surgically remove the cyst or remove the ovary with the cyst inside, depending on the age of the women and whether she wishes to have children. In some cases however, it is difficult to differentiate between a cystadenoma of low malignancy and a borderline malignancy cyst so removal of the ovary is often the preferred treatment.

Endometriomas

Characterized by the presence of endometrial lining entopic in the ovary. They may be associated with a previous history of endometriosis. Women typically present with pelvic pain and may have a palpable adnexal mass. The cyst contents may be hemorrhagic, so-called « chocolate cyst, » appearing as homogeneous low-level echoes with occasional acoustic shadowing on ultrasound. Surgical cystectomy is the treatment of choice. Ovarian cancer is a risk in patients with long-term endometriomas, particularly if they are bilateral and diagnosed in postmenopausal women. Endometrioid and clear cell ovarian cancers can arise in association with endometriosis and can potentially be mistaken for a primary endometrioid or clear cell cancer of the ovary. Tumor and cyst removal is the treatment of choice in early disease. Hysterectomy and bilateral salpingo-oophorectomy may be indicated in severe cases when fertility is no longer desired.