An ovarian cyst is any collection of fluid, surrounded by a very thin wall, within an ovary. Any ovarian follicle that is larger than about two centimeters is termed an ovarian cyst. Such cysts range in size from as small as a pea to larger than an orange.
Most ovarian cysts are functional in nature and harmless (benign).
Ovarian cysts affect women of all ages. They occur most often, however, during a woman's childbearing years.
Some ovarian cysts cause problems, such as bleeding and pain. Surgery may be required to remove cysts larger than 5 centimeters in diameter.
Ovarian cysts may be classified according to whether they are a variant of the normal menstrual cycle, called a functional cyst, or not.
Functional cysts form as a normal part of the menstrual cycle. Such cysts may include:
Follicular cyst, the most common type of ovarian cyst. In menstruating women, a follicle containing the ovum (unfertilized egg) will rupture during ovulation. If this does not occur, a follicular cyst of more than 2.5 cm diameter may result.
Thecal cysts occur within the thecal layer of cells surrounding developing oocytes. Under the influence of excessive hCG, thecal cells may proliferate and become cystic. This is usually on both ovaries.
A hemorrhagic ovarian cyst, probably originating from a corpus luteum cyst. The coagulating blood gives the content a spider web-like appearance.
Benign ovarian cysts are common in unsymptomatic premenarchal girls and found in approximately 68% of ovaries of girls 2-12 years old and in 84% of ovaries of girls 0-2 years old. Most of them are smaller than 9 mm while about 10-20% are larger macrocysts. While the smaller cysts mostly disappear within 6 months the larger ones appear to be more persistent.
If the cause is endometriosis, then periods may be heavy, and intercourse painful.
A 2cm left ovarian cyst as seen on ultrasound
An Axial CT demonstrating a large hemorrhagic ovarian cyst. The cyst is delineated by the yellow bars with blood seen anteriorly.
Ovarian cysts are usually diagnosed by either ultrasound or CT scan, with additional endocrinological tests.
Follow-up imaging for women of reproductive age with small simple or hemorrhagic cyst is generally not required.
There are several systems for scoring of the risk of an ovarian cyst of being an ovarian cancer, including RMI (risk of malignancy index), LR2 and SR (simple rules). Sensitivities and specificities of these systems are given in tables below:
Risk of malignancy index
A widely recognized method of estimating the risk of malignant ovarian cancer based on initial workup is the risk of malignancy index (RMI).
It is recommended that women with an RMI score over 200 should be referred to a center with experience in ovarian cancer surgery.
A warm bath, or heating pad, or hot water bottle applied to the lower abdomen near the ovaries can relax tense muscles and relieve cramping, lessen discomfort, and stimulate circulation and healing in the ovaries.
Combined methods of hormonal contraception such as the combined oral contraceptive pill – the hormones in the pills may regulate the menstrual cycle, and prevent the formation of follicles that can turn into cysts.(American College of Obstetricians and Gynecologists, 1999c; Mayo Clinic, 2002e) However, a Cochrane review in 2011 concluded oral contraceptives are of no benefit in treating already present functional cysts.
Also, limiting strenuous activity may reduce the risk of cyst rupture or torsion.
Cysts that persist beyond two or three menstrual cycles, or occur in post-menopausal women, may indicate more serious disease and should be investigated through ultrasonography and laparoscopy, especially in cases where family members have had ovarian cancer. Such cysts may require surgical biopsy. Additionally, a blood test may be taken before surgery to check for elevated CA-125, a tumor marker, which is often found in increased levels in ovarian cancer, although it can also be elevated by other conditions resulting in a large number of false positives.
For more serious cases where cysts are large and persisting, doctors may suggest surgery. This may involve removing the cyst, or one or both ovaries. Features that may indicate the need for surgery include:
A rupture of an ovarian cyst is usually a self-limiting, and only requires expectant management and analgesics. The main symptom is abdominal pain, but can also be asymptomatic. The pain may last from a few days to several weeks.
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