What is the primary purpose of using a coupling gel in ultrasound?

The primary purpose of using coupling gel in ultrasound is to eliminate air between the transducer and the skin, facilitating sound wave transmission. This is essential because ultrasound waves travel best through liquid rather than gas; air can create an acoustic barrier that significantly impedes the passage of sound waves. The gel creates a continuous medium for the sound waves, helping them to transmit more efficiently from the transducer into the body and back.

While other options may address aspects of ultrasound procedures, they do not accurately represent the fundamental role of coupling gel. For instance, enhancing sound wave reflection or increasing the speed of sound waves does not occur with gel application; rather, the gel's presence is pivotal for minimizing reflections at the skin interface and improving the quality of the received signals. Protecting the skin is also not the primary function of the gel; it is more about ensuring effective acoustic transmission.