[Scrotal ultrasound examinations in infants and toddlers]. 
Besides physical examination, ultrasonography is the most valuable diagnostic tool to assess the scrotum and testes in the case of an acute scrotum or scrotal pathology.  In infants and toddlers the examination can be challenging.  Due to the limited patient compliance, the small testicular size (< 0.5 ml), and low blood flow velocity (< 3 cm/s), it can be difficult to achieve a proper flow curve when assessing blood flow.  The examiner's skills are as important as adequate equipment (i. e., linear ultrasound probe, 12-14 MHz) and optimal program settings (Doppler scale < 3 cm/s, gate 1 mm).  However, if there is doubt, surgical exploration is unavoidable.