Ultrasound guidance for peripheral nerve blocks is increasing in popularity. The real-time visualisation of the nerve, the needle advancement and local anaesthetic deposition has been shown to decrease procedural times and increase block quality (1-4). Chan et al described that ultrasound-assisted sciatic nerve localisation is potentially valuable for sciatic nerve blocks (5). To anaesthetise the lower limb, the sciatic nerve block is commonly combined with femoral nerve block and relatively large doses of local anaesthetic are injected. Prudent selection of local anaesthetic concentration and volume is needed to decrease the risk of systemic toxicity (6).