Pelvic floor muscle function differs between supine and standing positions in women with stress urinary incontinence:...

In women with stress urinary incontinence, how does pelvic floor muscle (PFM) function differ between supine and standing when assessed using manometry, vaginal palpation, dynamometry and electromyography?

An experimental crossover study.

A total of 101 women with stress urinary incontinence were included.

The PFM evaluations were performed and compared in supine and standing positions. The participants were assigned to either Group 1 (assessments in supine followed by standing) or Group 2 (assessments in standing followed by supine).

The primary outcome was the PFM pressure during the maximum voluntary contraction (MVC). Secondary outcomes were the measures of PFM pressure at rest; PFM function (PERFECT scheme); active and passive forces (dynamometry); and PFM electromyography (EMG) activity.

The mean MVC pressure was significantly lower in standing (MD -7 cmH₂O, 95% CI -10 to -4). The mean PFM resting pressure was higher in standing (7 cmH₂O, 95% CI 5 to 10). Three measures of PFM function derived from vaginal palpation were better in supine than in standing. The PFM active and the passive forces measured using dynamometry were higher in standing (0.18 kgf, 95% CI 0.16 to 0.20). The resting EMG activity was higher in standing than in supine (MD 3.6 μV, 95% CI 2.6 to 4.5), whereas EMG activity during MVC was higher in supine than standing (MD -8.7 μV, 95% CI -12.5 to -4.8).

The pressure and EMG activity during MVC, and PFM function were lower in standing. The resting pressure, the passive and active forces of the PFM and the resting EMG activity of the PFM were higher in standing.