Ovarian cysts are extremely common. These fluid-filled sacs that form on or within the ovaries are usually harmless, temporary, and resolve without intervention. When a cyst is classified as “complex,” it simply means the structure is more intricate than a standard fluid-filled sac, indicating a need for a closer look and more detailed assessment. While this classification can cause worry, the vast majority of complex ovarian cysts are not cancerous and can often be safely managed without immediate surgery.
Defining Complexity: Simple vs. Complex Cysts
The distinction between a simple and a complex ovarian cyst relies entirely on its internal structure. A simple cyst is a purely fluid-filled sac with thin, smooth walls and no internal features. On an ultrasound, this appears anechoic, meaning it is uniformly black, reflecting no sound waves back to the probe. Simple cysts are often functional cysts, forming as a normal part of the menstrual cycle, and typically disappear within a few cycles.
A complex cyst, by contrast, contains something other than thin, clear fluid, giving it a mixed appearance on imaging. This complexity can manifest as internal walls, known as septations, which divide the cyst into multiple compartments. It might also contain solid areas, blood, or thick, mucous-like material, which makes the internal area appear brighter, or echogenic, on the ultrasound screen. This structural variation prompts classification as complex.
Specific Complex Cyst Types
The complex appearance of a cyst is caused by its specific contents. One common type is an endometrioma, which forms in individuals with endometriosis when tissue similar to the uterine lining grows on the ovary. These are often called “chocolate cysts” because they are filled with old, thick, brownish blood.
Dermoid cysts, technically known as mature cystic teratomas, are another frequent type that develops from germ cells present since birth. These cysts appear complex because they can contain various types of mature tissue, such as fat, hair, skin, or even teeth. Cystadenomas are complex masses that grow from the surface of the ovary and can become quite large, filled with either thin, watery fluid (serous) or a thick, sticky substance (mucinous).
Diagnostic Procedures and Evaluation
Once an ovarian cyst is identified, usually during a routine exam or imaging, the diagnostic process begins. Transvaginal ultrasound (TVS) is the primary tool used for assessment, providing high-resolution images of the cyst’s specific characteristics. Clinicians use TVS to measure the cyst’s size, assess the thickness of its walls, and look for specific features like septations or solid components.
Doppler flow studies are performed during the ultrasound to check for blood flow within solid areas or septations, as increased vascularity can be a feature of a malignant growth. If ultrasound findings are uncertain, a Magnetic Resonance Imaging (MRI) scan may be ordered. MRI offers superior soft tissue contrast, helping characterize internal contents, such as identifying fat in a dermoid cyst or old blood in an endometrioma.
Blood tests for the tumor marker CA-125 are used as part of the evaluation process. CA-125 is a protein that can be elevated in cases of ovarian cancer, but it is not a standalone diagnostic test. Levels can also be raised by common non-cancerous conditions, including endometriosis, pelvic inflammatory disease, and uterine fibroids. Therefore, this test is most useful when combined with imaging results and menopausal status to calculate a comprehensive risk assessment.
Management and Monitoring Strategies
The clinical approach for a complex ovarian cyst is individualized, determined by the cyst’s size, its appearance on imaging, and the patient’s symptoms and age. For many smaller, complex cysts that show features consistent with known benign types like endometriomas or dermoids, “watchful waiting” is often recommended. This involves monitoring the cyst with repeat ultrasound scans, typically scheduled every few months, to track changes in size or structure.
Surgical intervention is generally reserved for cysts that are causing persistent, severe symptoms or those that meet criteria suggesting a higher risk. These criteria often include a cyst size greater than 10 centimeters, persistent growth over several monitoring periods, or suspicious features such as thick, irregular walls or significant solid components with blood flow. Surgery is also performed if there is a risk of ovarian torsion, a painful twisting of the ovary.
The surgery is performed using a minimally invasive laparoscopic technique, which involves small incisions and a quicker recovery time. The goal is cystectomy—removing the cyst while preserving the ovary whenever possible. If the cyst is very large, the entire ovary may need to be removed, or a traditional open procedure called a laparotomy may be necessary.