ARDMS (American Registry for Diagnostic Medical Sonography) Practice Test

A simple cyst typically appears anechoic on ultrasound, meaning it does not produce echoes and appears completely dark on the ultrasound image. This characteristic is due to the fluid inside the cyst, which does not reflect the ultrasound waves. When surrounded by normal tissue, the absence of internal echoes confirms the fluid nature of the cyst, allowing for easy differentiation from solid masses or complex cystic structures that may contain debris or solid components.

In contrast, other echogenicities such as hyperechoic (brighter than surrounding tissues), hypoechoic (darker than surrounding tissues), or isoechoic (similar echogenicity to surrounding tissues) are indicative of different tissue compositions and structures, which do not describe a simple cyst's typical appearance. Simple cysts, being fluid-filled, are thus anechoic and are considered benign structures with clear borders on ultrasound imaging.