What defines a "complex cyst" on an abdominal ultrasound?

A "complex cyst" on an abdominal ultrasound is characterized by having both solid and cystic components. This definition is crucial because it indicates that the cyst may not be a straightforward fluid-filled structure. In medical imaging, the presence of solid components within a cyst can suggest the need for further evaluation, as it may indicate potential pathology such as infection, hemorrhage, or neoplasia.

In contrast, entirely fluid-filled structures are classified as simple cysts, which generally have a distinct anechoic appearance on ultrasound and are typically considered benign. A solid mass with no fluid content would not be classified as a cyst at all, and thus falls outside the definition. Similarly, a simple mass with minimal echogenicity may not have the necessary components to be considered complex. Understanding these definitions helps in distinguishing between the types of lesions encountered in the abdomen and emphasizes the need for careful interpretation of ultrasound findings.