Static or Real-time
Ultrasound guidance or ultrasound-assisted procedures can be performed using ultrasound in one of two ways:
Static approach
With the static approach, anatomic structures are identified and an insertion position is identified with ultrasound. This may be marked on the skin. The cannulation then proceeds as it would without ultrasound and is not performed with the transducer imaging the needle being introduced or entering the vessel. Its use is merely to demonstrate the position of the vessel. In most instances this is sub-optimal, and not recommended.
Real time
In real-time, the ultrasound transducer is placed in a sterile covering and the procedure is performed with simultaneous ultrasound visualisation of the cannulation. This is recommended.
Ultrasound can be used simply to identify the vein position, or to aid cannulation.