Assessment of abdominal, diaphragm, and pelvic floor muscle function during respiratory tasks using transabdominal ultrasound in women with and without postpartum stress urinary incontinence.

OBJECTIVES To compare the function of abdominal, diaphragm, and pelvic floor muscles during respiratory tasks among women with postpartum stress urinary incontinence (PPSUI), postpartum continent women, and healthy nulliparous women. DESIGN A cross-sectional study. SETTING The Department of Obstetrics at a tertiary hospital in Shenzhen, China. PARTICIPANTS A total of 162 women, including 54 women with PPSUI, 54 postpartum continent women, and 54 healthy nulliparous women. MAIN OUTCOME MEASURES Pelvic floor muscle activity, diaphragm excursion and thickness, and abdominal muscle activity were assessed at rest, during maximum deep respiration and during maximum voluntary cough using transabdominal ultrasound. RESULTS Women with PPSUI showed significantly smaller transversus abdominis thickness change at the end of maximum deep expiration [26 (17) %] compared to postpartum continent women [59 (19) %, P < 0.05] and healthy nulliparous women [62 (20) %, P < 0.05]. They also exhibited greater pelvic floor muscle activity at the end of maximum deep expiration [5.4 (2.0) mm] than postpartum continent [3.2 (1.5) mm, P < 0.05] and healthy nulliparous women [3.0 (1.4) mm, P < 0.05]. In addition, diaphragm excursion during maximum deep respiration was smaller in the PPSUI group [44.8 (8.0) mm] compared to the healthy nulliparous group [57.1 (6.9) mm, P < 0.05]. CONCLUSION Women with PPSUI exhibited reduced thickness change of abdominal muscles, limited diaphragm excursion, and increased pelvic floor muscle activity during tasks that increase intra-abdominal pressure. These findings suggest that impaired core muscle coordination may contribute to postpartum stress urinary incontinence. CONTRIBUTION OF THE PAPER.