How Safe Is Ultrasound

Ultrasound has been shown to be relatively safe, but no imaging method which deposits additional energy into the body should be considered entirely risk free.

When the decision to make a diagnostic image is made, the physician should always make a conscious judgement about whether the potential benefits of the imaging procedure are greater than any potential risk. As kinetic energy is introduced into tissue, there is potential for both thermal and mechanical damage to cells.

Fractional increases in tissue temperature occur and varying degrees of cell damage have been observed.  While there is no evidence that ultrasound has resulted in actual harm, the fact that these effects may occur should be borne in mind.  For this reason, it is considered good practice to avoid extensive periods of scanning in one patient, unnecessary repeats, unwarranted foetal exposure etc.

Anyone undertaking diagnostic ultrasound examinations should comply with the British Medical Ultrasound Society guidelines for the safe use of ultrasound equipment. A link to the guidelines can be found in the Web resources page in the Session Summary.

A further potential hazard of ultrasound is the risk of cross infection. Transducers should be cleaned after each patient with a non-alcohol based cleaning fluid or wipe.  Alcohol based cleaners should be avoided as, over time, these will dissolve the thin protective layer that covers the transducer crystals and will invalidate any warranty.

Learning bite

Particular care should be taken when scanning:

• An embryo less than eight weeks after conception
• The head, brain or spine of any foetus or neonate
• An eye (in a subject of any age)

N.B. The use of Doppler is normally contraindicated in each of the above