Levator function and voluntary augmentation of maximum urethral closure pressure

Introduction and hypothesis The aim of the study was to test whether women with symptoms of pelvic floor dysfunction can augment maximum urethral closure pressure (MUCP) with a pelvic floor muscle contraction (PFMC) and whether augmentation is associated with structure and function of the levator ani muscle. Methods Between January and December 2009, 300 women attended a tertiary referral service for multichannel urodynamic testing and 4D pelvic floor ultrasound. The MUCP was obtained with a perfused fluid-filled catheter. Augmented MUCPs were obtained during directed PFMC. Levator contraction strength was assessed digitally, using the Modified Oxford Grading (MOS). Levator integrity was determined using tomographic ultrasound, and we also measured dimensions of the levator hiatus at rest and on PFMC, blinded against all clinical data. Results The MUCP was measured at a mean of 36 cm H₂O (range 2-111). Augmented MUCP was 42 cm H₂O on average (4-125). Of those who attempted augmentation (n0275), 80 produced a reduction in MUCP and were excluded, leaving 195. There was a significant correlation between MOS and augmentation (r=0.24, P=0.001).Women with an intact levator muscle were able to augment more effectively (P=0.038). Conclusions Urethral closure pressure can be augmented voluntarily by symptomatic patients, on average by about 20 %. The degree of augmentation is positively associated with levator contractility as measured by digital palpation and negatively with levator avulsion.