In ultrasound terminology, what does the term "hypoechoic" refer to?

The term "hypoechoic" refers to an area that reflects fewer sound waves compared to the surrounding tissues. In ultrasound imaging, different tissues reflect sound waves differently, resulting in varying levels of echogenicity. Hypoechoic areas will typically appear darker on the ultrasound image than the surrounding tissues, indicating lower levels of sound reflection.

This term is often used to describe certain types of tissues or pathological conditions, such as a fluid-filled structure or certain types of tumors that do not reflect as many sound waves as adjacent tissues. Understanding the echogenicity of structures is crucial in diagnostic sonography, as it helps in differentiating between various tissues and potential abnormalities.