An Approach to Assessment of Female Urinary Incontinence Risk Using the Thickness of the Transverse Abdominal Muscle

Abstract

[Purpose] This study examined physical factors associated with urinary incontinence (UI) in women. We hypothesized that, women with UI would show decreased thickness of the transverse abdominal muscle (TA) during maximal co-contraction of both TA and the pelvic floor muscle (PFM) compared with women with no history of UI. [Subjects] The subjects were seventy-one women who were divided into two groups: the UI group and the No-UI group. [Methods] We evaluated the thickness of TA and obliquus internus muscle (OI) using ultrasound, and measured hand-grip strength. The thickness of TA was measured while subjects performed 5 tasks: (1) at rest, (2) maximal contraction of TA, (3) maximal contraction of PFM, (4) maximal co-contraction of both TA and PFM, and (5) bridging motion. [Results] The No-UI group had many subjects who had thicknesses of TA which the UI group had in the tasks 2, 3 and 4. In logistic regression analysis with UI as the dependent variable, the thickness of TA during maximal co-contraction was identified as an independent factor, and the cut-off value of the thickness of TA was 5.00 mm as determined by the Receiver-Operating-Characteristic (ROC) curve. [Conclusion] We demonstrated that the thickness of TA in maximal co-contraction of both TA and PFM is reliable and useful for evaluating the risk of UI in women.