Ovarian cysts are common during pregnancy. These fluid-filled sacs on or within the ovaries are often benign and frequently discovered during routine prenatal ultrasounds. While the presence of a cyst can be concerning for expectant mothers, most do not cause significant problems. Ovarian masses are diagnosed in approximately 0.5% to 1% of pregnancies, with many resolving on their own.
Types of Ovarian Cysts During Pregnancy
Functional cysts are the most common type of ovarian cyst during pregnancy, forming as a normal part of the menstrual cycle. Follicular cysts develop when a follicle containing an egg fails to rupture and release the egg, instead continuing to grow. Corpus luteum cysts, another functional type, form after ovulation when the follicle that released the egg fills with fluid instead of shrinking. These cysts are a normal part of early pregnancy, producing progesterone to support it until the placenta takes over, and usually resolve by the middle of the second trimester.
Other benign non-functional cysts can also be present. Dermoid cysts, also known as mature cystic teratomas, arise from reproductive cells and can contain various tissues like hair, skin, or teeth. These cysts are generally benign, though they can rarely become cancerous. Serous or mucinous cystadenomas are other benign types that grow on the outer surface of the ovary, filled with watery or mucinous material, and can sometimes grow quite large.
Less common types of cysts, such as endometriomas and theca-lutein cysts, may also be found. Endometriomas, often called “chocolate cysts,” occur in individuals with endometriosis, a condition where uterine-like tissue grows outside the uterus, forming cysts filled with old blood. Theca-lutein cysts are usually bilateral and result from exaggerated hormonal stimulation, often associated with elevated levels of human chorionic gonadotropin (hCG). They are seen in conditions like gestational trophoblastic disease or multiple gestations, though rarely in uncomplicated singleton pregnancies.
Symptoms and Diagnosis
Many ovarian cysts during pregnancy are asymptomatic, causing no noticeable symptoms. These cysts are frequently discovered during routine prenatal ultrasound examinations, a standard part of obstetric care.
When symptoms occur, they can include pelvic pain, which might be a dull ache or a sharp, sudden sensation on one side of the lower abdomen. Other potential symptoms include a feeling of abdominal fullness, pressure, or bloating. Less commonly, vaginal bleeding or pain during bowel movements may be experienced.
Ultrasound is the primary and safest diagnostic tool for evaluating ovarian cysts during pregnancy. A transvaginal ultrasound provides detailed images, allowing providers to assess the cyst’s size, location, and internal characteristics, such as whether it is fluid-filled or contains solid components. This imaging helps determine the nature of the cyst and guides subsequent management decisions.
Managing Ovarian Cysts in Pregnancy
For most small, asymptomatic ovarian cysts that appear benign on ultrasound, a “watchful waiting” approach is recommended. Many functional cysts, especially corpus luteum cysts, resolve by 16 to 20 weeks of gestation.
Cysts are monitored through serial ultrasounds to track any changes in their size or characteristics. If a cyst is larger than 5-6 cm or has complex features, follow-up imaging is advised around 16 weeks of gestation to allow for potential resolution.
Surgical intervention is considered for specific scenarios, such as cysts that are large (e.g., over 10 cm), rapidly growing, or exhibit suspicious features that might indicate a rare malignancy. Surgery may also be necessary if the cyst causes significant symptoms or complications like torsion or rupture. If surgery is needed, it is performed during the second trimester, usually between 16 and 20 weeks, to minimize risks to both the pregnant individual and the fetus. Surgical options include minimally invasive laparoscopic surgery or open abdominal surgery, depending on the cyst’s size and characteristics.
Potential Complications
While most ovarian cysts during pregnancy are benign and resolve without issues, some can lead to complications. One such complication is ovarian torsion, where the ovary twists around its blood supply, causing sudden and severe abdominal pain, often accompanied by nausea and vomiting. Ovarian torsion is a medical emergency that requires immediate surgical intervention to restore blood flow to the ovary.
Another potential complication is cyst rupture, where the fluid-filled sac breaks open. This can cause sudden, sharp pain in the lower abdomen, and in some cases, internal bleeding, which may manifest as dizziness or weakness. Although often self-limiting for benign cysts, severe cases may require medical attention. Hemorrhage within the cyst can also occur, leading to pain and enlargement.
Although rare, there is a possibility of malignancy, especially for cysts with suspicious features on imaging. Very large cysts might also physically obstruct the birth canal, potentially necessitating a Cesarean section for delivery. However, most benign cysts do not negatively impact the overall pregnancy outcome or mode of delivery.