High-Resolution ultrasound of the pudendal nerve: Normal anatomy

Introduction: In this study we aimed to determine whether high-resolution ultrasound (US) can identify the pudendal nerve and its terminal branches. We also attempted to identify the best approach for visualizing these structures. Methods: Normal anatomy of the pudendal nerve was evaluated in 3 cadavers and 20 healthy volunteers proximally at the level of the ischial spine and distally with low-frequency (2–5-MHZ) and high-frequency (12–7-MHZ and 17–5-MHZ) transducers. Two musculoskeletal radiologists performed the examinations and evaluations. Volunteers were placed in 3 different positions, which allowed different approaches (posterior, medial, and anterior transperineal). A 0–3 scale was used to assess nerve visibility. Results: Visualization of the pudendal nerve at the ischial spine was best when using a medial approach (P < 0.004); the terminal branches were seen best with the anterior approach (P < 0.002). Conclusion: High-resolution ultrasound (US) can identify the pudendal nerve and its terminal branches. Muscle Nerve 47:403-408, 2013