Twenty RCTs and three case series were included in the review (n=2,649 patients).
Peripheral nerve blocks (11 RCTs of adults, three RCTs of children and two case series): Seven RCTs of adults for upper extremity blocks reported a non-significant difference in failed block between ultrasound-guided blocks and controls. Four RCTs reported a non-significance difference in onset of surgical anaesthesia. Four RCTs of adults for lower extremity and low body blocks reported no difference in failed blocks between ultrasound-guided blocks and controls. One RCT of children reported that ultrasound-guided blocks were significantly associated with a longer duration of analgesia compared with controls. Two RCTs of children reported a significant lower volume of local anaesthetic needed for ultrasound-guided blocks in comparison with controls. Two case series reported greater than 98% success rate in ultrasound-guided peripheral nerve blocks.
Central neuraxial blocks (six RCTs and one case series): Two RCTs reported that there were no differences in failed blocks between ultrasound-guided blocks and controls. One RCT reported that ultrasound-guided blocks were significantly associated with a lower rate of postpartum headache and backache compared with controls. One case series reported that the epidural space was located with the first puncture attempt for almost all patients.
No serious complications were reported in any study.