The impact of pelvic floor contraction on urethral mobility and urogenital hiatus size in pelvic floor ultrasound

Aim The aim of the study was to assess the effect of pelvic floor contraction on urethral mobility and the size of the urogenital hiatus, as well as to compare two ultrasonographic approaches for the assessment of urethral mobility: transperineal with a transabdominal probe and transvestibular with a transvaginal transducer.Materials and methods Modified Oxford Scale (MOS) was used for clinical evaluation of muscle contraction. The parameters obtained in both ultrasound approaches were assessed for all six Oxford grades. The values of Delta H, Delta D and vector, measured at rest and on pelvic floor muscle contraction, were used to evaluate urethral mobility parameters in both ultrasound methods. Patients with a history of urogynecological surgery, pelvic radiotherapy, significant pelvic prolapse (grade 2 or grater in at least one compartment), as well as those with unilateral or bilateral complete avulsion of the puborectalis muscle were excluded.Results A total of 272 women were included in the analysis. A statistically significant correlation was found between the contraction force and urethral mobility parameters Delta H and vector-positive and Delta D-negative, obtained in both ultrasound approaches. However, no correlation was demonstrated between the contraction force and changes in the analyzed hiatal parameters. The Bland-Altman analysis showed a high agreement of both measurement methods.Conclusions The force of pelvic floor muscle contraction, as measured with the Oxford Scale, correlated with urethral mobility in both ultrasound examinations. Assessment of urethral mobility using the three assessed parameters (Delta H, Delta D, vector) allows for the most comprehensive analysis. Only minor differences were found in the analyzed urethral mobility parameters between both ultrasonographic approaches. The impact of pelvic floor muscle contraction on the size of the urogenital hiatus was not confirmed.