Ovarian cysts are fluid-filled sacs that grow inside or on top of one (or both) ovaries. A cyst is a general term used to describe a fluid-filled structure. Ovarian cysts are usually asymptomatic, but pain in the abdomen or pelvis is common.
The ovaries are reproductive organs in women that are located in the pelvis. One ovary is on each side of the uterus, and each is about the side of a walnut. The ovaries produce eggs and the female hormones, estrogen and progesterone. The ovaries are the main source of female hormones that control sexual development including breasts, body shape, and body hair. The ovaries also regulate the menstrual cycle and pregnancy.
Ovulation is controlled by a series of hormone chain reactions originating from the brain’s hypothalamus. Every month, as part of a woman’s menstrual cycle, follicles rupture, releasing an egg from the ovary. A follicle is a small fluid sac that contains the female gametes (eggs) inside the ovary. This process of releasing and egg from the ovary an into the Fallopian tube is known as ‘ovulation’.
Ovarian Cyst Risk Factors
The following are potential risk factors for developing ovarian cysts:
- History of previous ovarian cysts
- Irregular menstrual cycles
- Polycystic ovarian syndrome
- Early menstruation (11 years or younger)
- Tamoxifen therapy for breast cancer
Types of Ovarian Cyst
Functional Ovarian Cysts
There are two types of functional ovarian cysts: follicle cysts and corpus luteum cysts.
Follicular cysts contain a follicle that has failed to rupture and filled with more fluid instead. Corpus luteum cysts occur when the follicle ruptures to release the egg, but then seals up and swells with fluid. Corpus luteum cysts can be painful and cause bleeding. When bleeding occurs in a functional cyst, it is known as a hemorrhagic cyst.
Complex Ovarian Cysts
Other types of ovarian cysts may be associated with endometriosis, polycystic ovarian syndrome (POS) and other conditions. Polycystic ovaries occur when the ovaries are abnormally large and contain many small cysts on the outer edges.
Non-cancerous growths that develop from the outer lining tissue of the ovaries are known as cystadenomas. A cyst can also develop when uterine lining tissue grows outside the uterus and attaches to the ovaries; this is known as an endometrioma.
Ovarian Cysts During Pregnancy
Ovarian cysts during pregnancy are usually functional ovarian cysts discovered in the first trimester. Ovarian cysts during pregnancy tend to resolve on their own before childbirth.
Signs and Symptoms of Ovarian Cyst
Many times ovarian cysts do not cause symptoms. When symptoms do occur, they may include the following:
- Pain during intercourse or menstruation
- Abdominal fullness
- Unusual bleeding
- Weight gain
- Inability to empty the bladder completely
- Breast pain
- Aching in the pelvic region, lower back, or thighs
The following symptoms need immediate medical attention:
- Severe abdominal pain that comes on suddenly (may be a a sign of a ruptured ovarian cyst)
- Rapid breathing
- Abdominal pain that occurs with vomiting and a fever
Diagnosis of Ovarian Cyst
Pelvic and Transvaginal Ultrasound
Ovarian cysts are often detected during a pelvic exam. A pelvis ultrasound can allow the doctor to see the cyst with sound waves and help determine whether it is comprised of fluid, solid tissue, or a mixture of the two. A transvaginal ultrasound consists of a doctor inserting a probe into the vagina in order to examine the uterus and ovaries. The examination allows the doctor to view the cyst in more detail.
During laparoscopic surgery, a doctor will make small incisions and pass a thin scope (laparoscope) through the abdomen. The laparoscope will allow the doctor to identify the cyst and possibly remove or biopsy the cyst.
Serum CA-125 Assay
A cancer-antigen 125 (CA-125) blood test can help suggest if a cyst is due to ovarian cancer, but other conditions — including endometriosis and uterine fibroids — can also increase CA-125 levels, so this test is not specific for ovarian cancer. In some cases of ovarian cancer, levels of CA-125 are not elevated enough to be detected by the blood test.
The doctor may order a pregnancy test and assess hormone levels. Blood tests can also be performed to test for other hormones that may cause polycystic ovarian syndrome.
A fluid sample from the pelvis may be taken in order to rule out bleeding into the abdominal cavity. Culdocentesis is performed by inserting a needle through the vaginal wall behind the uterine cervix.