Pitfalls of contemporary ultrasonography are connected with two groups of possible risks. The first of them is a biological risk, resulting from interaction of ultrasound energy with tissue structures. The effectiveness of two main risk factors, heating and cavitation, is expressed by means of two safety indices – thermal (TI) and mechanical (MI) – which are displayed on the screen during examination. In this connection it is necessary to bear in mind the increasing sensitivity of some tissues to ultrasound resulting in certain ultrasound intensity constrains for obstetrics, paediatrics and ophthalmology. The implementation of the carefulness principle (ALARA) ensures that the total ultrasound energy is maintained below the level of its biological efficiency while diagnostic information is preserved. Moreover this type of risk is permanently monitored by several international organisations. However, less attention is devoted to non-biological risks consisting in erroneous examination or in incorrect interpretation of the final image. The reason consists in insufficient knowledge of topographic anatomy and in unskilled manipulation with the scan head. Finally, some guidelines for minimizing of possible risks in ultrasound imaging as well as in Doppler methods are introduced.

        Key words: ultrasonography – biological and non-biological risks – ALARA principle – safety indices