Objectives. To explore the urodynamic significance of abdominal straining during voiding in female subjects with lower urinary tract symptoms. Methods. We retrospectively reviewed a urodynamic database to identify the 180 patients who met the inclusion criteria for this study. None had a history of pelvic surgery, neuropathy, diabetes mellitus, or subjective complaints of voiding difficulty (poor stream, straining to void, hesitancy, or incomplete emptying). None had distortion or compression of the urethra or urodynamic findings of genuine stress incontinence, overactive detrusor, or hypersensitive bladder. All had undergone the pressure-flow study as part of a full urodynamic study to investigate the voiding mechanism. Of the 180 subjects, 100 women were premenopausal and 80 were postmenopausal. One half of the patients in each group had abdominal straining during voiding; the other half did not. Abdominal straining was defined as an increase in abdominal pressure of at least 10 cm H2O greater than baseline, regardless of duration and patterns. Differences in demographics, anatomy, and urodynamic study findings in those with and without abdominal straining were compared in each group. Results. In premenopausal women, the intravesical opening pressure differed significantly between those with and without abdominal straining (P = 0.011); in postmenopausal women, the significant urodynamic difference was the time to peak flow and minimal urethral resistance (P = 0.017 and 0.023, respectively). Menopause did not affect the voiding patterns. Conclusions. Although the clinical manifestation is devoid of voiding difficulty, straining at voiding in female subjects with lower urinary tract symptoms is significantly associated with the urodynamic parameters signifying urethral obstruction, and is a compressive effect in premenopausal women and a constrictive effect in postmenopausal women.
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