Morphometry of the Pelvic Floor Muscles in Women With and Without Provoked Vestibulodynia Using 4D Ultrasound

INTRODUCTION: It has been suggested that pelvic floor muscles (PFMs) play an important role in provoked vestibulodynia (PVD) pathophysiology. Controversy in determining their exact contribution may be explained by methodological limitations related to the PFM assessment tools, specifically the pain elicited by the measurement itself, which may trigger a PFM reaction and introduce a strong bias. AIM: The aim of this study was to compare PFM morphometry in women suffering from PVD to asymptomatic healthy control women using a pain-free methodology, transperineal four-dimensional (4D) ultrasound. METHODS: Fifty-one asymptomatic women and 49 women suffering from PVD were recruited. Diagnosis of PVD was confirmed by a gynecologist following a standardized examination. All the participants were nulliparous and had no other urogynecological conditions. The women were evaluated in a supine position at rest and during PFM maximal contraction. MAIN OUTCOME MEASURES: Transperineal 4D ultrasound, which consists of a probe applied on the surface of the perineum without any vaginal insertion, was used to assess PFM morphometry. Different parameters were assessed in sagittal and axial planes: anorectal angle, levator plate angle, displacement of the bladder neck, and levator hiatus area. The investigator analyzing the data was blinded to the clinical data. RESULTS: Women with PVD showed a significantly smaller levator hiatus area, a smaller anorectal angle, and a larger levator plate angle at rest compared with asymptomatic women, suggesting an increase in PFM tone. During PFM maximal contraction, smaller changes in levator hiatus area narrowing, displacement of the bladder neck, and changes of the anorectal and of the levator plate angles were found in women with PVD compared with controls, which may indicate poorer PFM strength and control. CONCLUSION: Using a reliable and pain-free methodology, this research provides sound evidence that women with PVD display differences in PFM morphometry suggesting increased tone and reduced strength.