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Background and Aims The pudendal nerve block has clinical applications in obstetric anesthesia, post-surgical perineal analgesia, and chronic perineal pain management. To conduct an anatomical study to evaluate the ultrasound-guided technique for blocking the pudendal nerve over the sacrospinous ligament (SPuB).Methods An anatomical study was conducted on fifteen cadaveric specimens (thirty pelvic girdles), in which the SPuB technique was performed under ultrasound guidance using a low-frequency convex transducer. Specimens were placed prone position, and the transducer was placed on the iliac bone in a superolateral oblique plane to identify the continuous bony structure. By sweeping the probe from superolateral to inferomedial, the continuous iliac bone, the beginning of the sciatic foramen, the greater sciatic notch, and the posteroinferior iliac spine were identified. At this point, the sacrospinous ligament was recognized, and by rotating the transducer into the sagittal plane, the sacrotuberous ligament was visualized superficially. Once the structures were identified, the probe was redirected to the sacrospinous ligament plane, and an in-plane lateral-to-medial puncture was performed with an 80-mm needle to inject 5 ml of a solution mixture (methylene blue + iodine). Three-dimensional (3D) reconstructions were obtained using computed tomography (CT), followed by sectional anatomy in five cadavers. Anatomical plane-by-plane dissection of each hemipelvis was carried out in ten cadavers.Results The 3D reconstruction obtained from CT demonstrated the contrast distribution from the lower sacral region in an oblique direction toward the posteroinferior iliac spine and the ischial tuberosity, partially covering the lesser sciatic foramen ( figure 1). In anatomical dissection and sectional anatomy, the distribution of methylene blue was observed within the plane formed by the sacrospinous and sacrotuberous ligaments, affecting the pudendal neurovascular bundle (figures 2 and 3).Conclusions The SPuB technique consistently affects the pudendal neurovascular bundle and is a simple and easily reproducible technique.Abstract EP097 Figure 1Three-dimensional (3D) reconstruction by computed tomography (CT) showing the contrast distribution after the application of the sacrospinous pudendal block (SPuB). Lateral left, posterior, and lateral right views of the bony pelvis are displayedAbstract EP097 Figure 2Sectional anatomy of the pelvis showing the distribution of methylene blue after the application of the sacrospinous pudendal block (SPuB). The magnified insets highlight the dye’s spread in the region of the pudendal neurovascular bundleAbstract EP097 Figure 3Anatomical dissection results after the application of the sacrospinous pudendal block (SPuB). The image shows methylene blue impregnation in the pudendal neurovascular bundle, delimited by the sacrospinous and sacrotuberous ligaments. The magnified inset highlights the dye’s spread along the pudendal nerve pathway