Transducer Handling

In 1999, the American Institute for Ultrasound Medicine (AIUM) established terminology to describe transducer manipulation.  These terms do not include specification of direction (i.e. proximal, distal, and clockwise).  When combined, these maneuvers can be used to optimize an ultrasound image by accounting for anatomical variances within the tissue.  While these terms and manipulations may seem like common sense or second nature, they provide a standardized vocabulary that can be very useful when describing how a particular image was obtained.

In general, a transducer can be manipulated in five ways:

  • Sliding
  • Tilting
  • Rocking
  • Rotating
  • Compressing


Before starting a procedure, ensure the transducer is properly orientated (discussed later).  Apply sufficient gel to the end of the transducer.  Gel serves as a coupler between air and the skin.  Without it, the significant differences in acoustic impedance between the air and tissue would cause the sound to be reflected; preventing it from entering the skin.  Place the transducer flat against the patient’s skin for maximum contact, with the ulnar aspect of the hand at the base of the transducer resting on the patient, as seen below left.  If the transducer is held too high, as in the picture on the right, it will be difficult to maintain a stable and consistent image.   Be gentle, but firm; the sound will penetrate tissue regardless of the pressure applied.  Initially, the transducer should be held perpendicular to the skin.  After obtaining a preliminary picture, it can then be manipulated to optimize the image.

Many regional procedures can be complicated by small blood vessels which course over or near the nerves.  Sliding enables the practitioner to evaluate the anatomy and determine the best location where the block can be completed effectively, but safely.


Air artifact occurs when the entire transducer is not contact with the skin.  This can occur when the transducer “footprint” is larger than the body surface being scanned (such as the ankle or wrist), or at areas where the body is not completely flat.  Rocking the transducer in the direction of the artifact, creates the contact that is needed to generate an image.

Tilting                                                                   The greatest reflection of sound occurs when the transducer is perpendicular to the desired structure to be imaged.  As nerves travel distally through the body, they often move from deep within the tissue to more superficial areas.  When this occurs the nerves are often not parallel with the skin/transducer interface.  Tilting the transducer can help create an angle closer to 90 degrees that will improve the reflection of the nerve, making it more visible on ultrasound.

As noted previously with sliding, regional anesthesia is often complicated by small blood vessels that travel around and near the nerves we wish to block.  Rotating the transducer allows the provider to optimize the desired structure in the image on the same plane while minimizing or avoiding complicating ones.


When structures deep in the tissue are imaged, the strength of the sound wave is reduced due to attenuation.  Because the returning signals are weak,  images may have poor resolution, making a block  difficult to perform.  Compressing is used to decrease space from the skin to the desired structure being imaged, improving resolution.  However, compressing can also collapse veins and even small arteries increasing the potential for vascular puncture.


AIUM Technical Bulletin. Transducer manipulation. American institute of ultrasound medicine. J Ultrasound Med. 1999; 18:169-175.


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