How do you know when to choose a higher or lower frequency probe on
ultrasound?

Choosing the right probe frequency comes down to balancing detail and depth. Higher frequency probes give excellent resolution for superficial structures, but the beam loses energy quickly—a process called attenuation—so the image fades as you go deeper.

Lower-frequency probes penetrate farther with less signal loss but sacrifice some fine detail. A simple rule of thumb is to use the highest frequency that still lets you reach the structure you want to see. Once you’re scanning around 6–8 cm deep, you may notice the image softening or dropping out, which is your cue to switch to a lower-frequency probe. This trade-off helps you pick the right tool for both clarity and depth.