In medical ultrasound, a refraction shadow is an artifact caused by the bending of the ultrasound beam as it passes through an interface between two tissues with different speeds of sound. This bending or refraction redirects sound waves away from structures behind the interface, creating a hypoechoic or anechoic (dark) area on the image. It is often seen at the edges of curved structures, such as blood vessels or cysts, and can obscure underlying anatomy, leading to misinterpretation.
Recognizing refraction shadows is crucial for accurate ultrasound diagnosis. Sonographers and radiologists must differentiate these artifacts from true pathology, such as calcifications or solid masses that produce acoustic shadowing. Adjusting the angle of insonation or transducer position can help minimize this artifact, improving image clarity and diagnostic confidence in ultrasound examinations.
