This study was conducted to evaluate the effects of a pelvic floor muscle (PFM) rehabilitation program on the striated urethral sphincter in women over 60 years with stress urinary incontinence (SUI). We hypothesized that the PFM rehabilitation program would also exercise the striated urethral sphincter and that this would be demonstrated by hypertrophy of the sphincter on magnetic resonance imaging (MRI). Women with at least weekly episodes of SUI were recruited. Participants were evaluated prior to and following a 12-week group PFM rehabilitation intervention with T2-weighted fast-spin-echo MRI sequences recorded in the axial plane at rest to assess urethral sphincter size. Data on SUI symptoms and their bother were also collected. No control group was included. Seventeen women took part in the study. The striated urethral sphincter increased significantly in thickness (21%, p < 0.001), cross-sectional area (20%, p = 0.003), and volume (12%, p = 0.003) following the intervention. The reported number of incontinence episodes and their bother was substantially reduced as well.
This study seems to show that PFM training for SUI also trains the striated urethral sphincter and that improvement in incontinence signs and symptoms is related to sphincter hypertrophy in older women with SUI. These findings support previous ultrasound (US) data showing an increase in urethral cross-sectional area following PFM training and extend the previous findings by more specifically assessing the area of hypertrophy and by demonstrating that older women present the same changes as younger women when assessed using MRI data.