Characterization of the Pudendal Nerve with Transvaginal Ultrasonography

This is a feasibility study characterizing the ability of transvaginal ultrasonography to identify the pudendal nerve. The pudendal nerve is a sensory and motor nerve arising from the sacral plexus, innervating the perineum. Anesthesia of the pudendal nerve (pudendal nerve block) is used to assist during obstetrical procedures (forceps delivery, vaginal tear repair), to improve discomfort associated with vaginal delivery when time is not sufficient to place an epidural, and to reduce pain following certain urogynecological surgeries [1-4]. Pudendal nerve block is also used to manage chronic pain associated with pudendal neuralgia [5]. Today, the pudendal nerve block is typically accomplished through blind landmark techniques, thus limiting its success [6-7]. More recently, efforts have been made to attempt this procedure with ultrasound from a more external approach transglutially, however this method requires high level of technical skill and is associated with high failure rate when compared to a blind landmark technique [8-10]. Other methods of accomplishing pudendal nerve blocks include the use of fluoroscopy. However, these renders the procedure more costly and subjects the patient to the inherent risk of radiation [11]. To date, there has never been an attempt to determine if the visualization of the pudendal nerve would be possible using transvaginal ultrasound with existing technology; nor to perform this procedure transvaginally with the assistance of ultrasound.