Background Performing spermatic cord block for scrotal surgery avoids the potential risks of neuraxial and general anaesthesia and provides long-lasting postoperative analgesia. A blindly performed block is often inefficient and bears its own potential risks (intravascular injection of local anaesthetics, haematoma formation and perforation of the deferent duct). The use of ultrasound may help to overcome these disadvantages. The aim of this study was to test the feasibility and monitor the success rate of a new ultrasound-guided spermatic cord block. Methods Twenty consecutive patients undergoing urologic surgery (subcapsular orchiectomy or vaso-vasostomy) were included in this prospective study. Using a linear ultrasound probe, the spermatic cord was identified by locating the spermatic artery and the deferent duct. A 23 G Microlance needle was advanced close to the deferent duct by avoiding vessel perforation, and local anaesthetic was deposited around the deferent duct under direct visualization. The primary outcome was the success rate of the block which was defined as surgery without any substitution of opioids, additional local anaesthetics, or sedatives. Results In 20 patients, 40 blocks were performed with a success rate of 95% (n=38). The failure rate was 5% (n=2) and no conversion to general anaesthesia was needed. The mean duration of the block was 14.1 h (sd 6.9). Conclusions The use of ultrasound guidance to perform spermatic cord block is feasible and has a high success rate. Our new approach may become a suitable alternative to neuraxial or general anaesthesia especially in the ambulatory surgical setting. Registry: International Standard Randomised Controlled Trial Number Register; www.controlled-trials.com; Registry Nr.: ISRCTN4464781
