Poster 6: Pudendal Nerve Block Prevents Shortening of the Puborectalis Muscle

Abstract

OBJECTIVE: The objective of this study was to evaluate the effect of pudendal nerve blockade on the anterior–posterior (A-P) length of the urogenital hiatus. METHODS: Transperineal 3-dimensional ultrasound imaging of the pelvic floor was performed in 11 normal nulliparous women at rest and during maximal contraction of the pelvic floor muscles. Simultaneous electromyography (EMG) of the puborectalis muscle was measured using bipolar needle electrodes in arbitrary units (au). Pudendal nerve block (PNB) was performed transvaginally with 10 cc of 1% lidocaine on each side. The ultrasound images were repeated after PNB at rest and during squeeze. The A-P length was measured from the inferior–posterior edge of the pubic bone to the apex of the anorectal angle as identified in the sagittal view. RESULTS: Before PNB, voluntary squeeze significantly increases EMG activity in the PRM. After PNB, the EMG activity of the PRM is significantly reduced. Before PNB, the A-P length decreases significantly with squeeze. After PNB, the A-P length increases at rest and the squeeze-related shortening is decreased. CONCLUSIONS: Contraction of the pelvic floor muscles causes a shortening in the A-P length of the genital hiatus, and this is blocked by a traditionally performed pudendal nerve blockade.FIGURE 1