Ovarian cysts are common fluid-filled sacs or masses that can develop on or within the ovaries. While many are benign and resolve without intervention, their presence often prompts medical evaluation. Ultrasound is a widely used imaging technique that helps visualize these cysts and assess their characteristics.
Understanding Ovarian Ultrasound
Ultrasound technology employs high-frequency sound waves to create images of internal body structures. A transducer sends these sound waves into the body; as they encounter tissues, they bounce back as echoes. These are processed by a computer to generate real-time images. Both transabdominal and transvaginal approaches are used for ovarian imaging. The transvaginal approach often offers clearer, more detailed images due to its closer proximity to the ovaries.
Typical Ultrasound Appearance of Ovarian Cysts
The appearance of an ovarian cyst on ultrasound varies significantly depending on its type and composition. Simple cysts, such as functional cysts, appear as fluid-filled, dark (anechoic) sacs with smooth, thin walls. These cysts often exhibit posterior acoustic enhancement, meaning the area behind the cyst appears brighter on the image due to the sound waves passing easily through the fluid. Follicular cysts, a type of functional cyst, typically appear unilocular (single compartment) and usually resolve on their own.
Corpus luteum cysts, which form after ovulation, can present with a more complex appearance on ultrasound. They may have thicker, sometimes crenulated, walls and can contain internal echoes due to blood or blood clots. Doppler ultrasound may reveal a characteristic “ring of fire” appearance, indicating rich blood flow around the periphery of the cyst. These cysts are common and often resolve spontaneously.
Endometriomas, sometimes called “chocolate cysts,” are ovarian cysts caused by endometriosis. They appear as “ground glass,” characterized by homogeneous low-level internal echoes. While usually unilocular, endometriomas can sometimes be multilocular. They generally do not show internal vascularity.
Dermoid cysts, also known as mature cystic teratomas, appear varied and complex due to containing different types of tissue like hair, fat, and even teeth. Common findings include a “Rokitansky nodule” or “dermoid plug,” which is a densely echogenic (bright) protuberance projecting into the cyst, often with acoustic shadowing behind it. Other signs can include fat-fluid levels, “floating spheres” (small echogenic structures), or a “dot-dash” pattern caused by hair within the cyst cavity.
Cystadenomas are a type of ovarian cyst, which can be serous or mucinous. Serous cystadenomas appear as simple, thin-walled, anechoic cysts, often unilocular but sometimes multilocular, filled with clear fluid. Mucinous cystadenomas tend to be larger and are usually multilocular, with numerous thin septations. The fluid within the locules may show varying degrees of echogenicity due to mucin content.
Key Characteristics Assessed on Ultrasound
Beyond identifying a cyst, specific characteristics observed on ultrasound help assess its nature and potential implications. The size of an ovarian cyst is a key factor, as larger cysts may warrant closer monitoring or further evaluation. For instance, simple cysts larger than 7 cm may prompt additional imaging or surgical consideration.
The appearance of the cyst’s walls and internal structure provides significant clues. Thin, smooth walls are generally associated with benign cysts, while thick or irregular walls can be a feature of more complex or potentially concerning lesions. The presence of septations is assessed; thin, few septations are less concerning than thick or numerous ones.
Any solid components or small growths (papulations) on the cyst wall are carefully examined. The presence of these solid areas, especially if they show blood flow on Doppler ultrasound, can raise suspicion. Doppler imaging helps evaluate vascularity, as increased blood supply within solid components can be an indicator of certain types of cysts. Additionally, the presence of free fluid in the pelvis (ascites) and how the cyst changes over time on follow-up scans are also important considerations in the overall assessment.
What Ultrasound Findings Mean
In most instances, an ovarian cyst detected on ultrasound is benign and may resolve without medical intervention. Functional cysts, which are the most common type, frequently disappear on their own within a few menstrual cycles. For simple, small, and asymptomatic cysts, a common approach is watchful waiting, where the cyst is monitored with follow-up ultrasound scans over several months to observe if it resolves or changes.
If a cyst has complex features, grows larger, or causes symptoms like pain, further testing may be recommended. This could include additional imaging like an MRI for more detailed characterization, or blood tests such as CA-125, which can be elevated in some ovarian conditions. Surgical intervention may be considered for cysts that are persistently symptomatic, very large, or exhibit suspicious features on ultrasound. It is important to remember that only a medical professional can provide an accurate diagnosis and determine the appropriate management plan based on all individual findings.