Randomised controlled pilot trial to assess effect of electrical stimulation of weak pelvic floor muscles

Pelvic floor muscle training (PFMT) has level 1A scientific evidence for the treatment of urinary incontinence and pelvic organ prolapse. Past studies, however, have often excluded women with very weak pelvic floor muscles (PFM). The aim was to investigate the hypothesis that intravaginal electrical stimulation (iES) improves PFM strength more than PFMT in women with weak PFM, and to use these results to calculate sample size required for a future large randomised controlled trial (RCT).

This assessor-blinded pilot RCT had a two arm, parallel design with computer-generated Randomisation. Both groups were offered 12 one-to-one physiotherapy sessions over a 6-month period. The iES group received individual tailored electrical pulse parameters. The PFMT group received PFM exercises, with the addition of facilitation techniques at therapy sessions. A power calculator was used to calculate sample size.

Fifteen women were recruited. Eight were randomised to iES and 7 to PFMT. Two subjects dropped out of the iES group. Median age was 49 years (range 36-77) and parity 2.1 (range 1-3). Both groups showed increases in PFM strength measured by manometery (iES 12.3, SD 12.0 vs PFMT 10.0, SD 8.1) cmH₂O. There was no significant difference between groups. With a power of 0.80 we need a sample size of 95 women in each group to detect a difference between groups.

There was no significant difference between the groups in improvements in PFM strength. To detect a difference, we would have required 95 women in each group.