Involuntary urine leakage has been observed during stress urethral pressure measurement in women with urodynamic stress incontinence (USI). However, to our knowledge, its clinical significance and urodynamic association remained undetermined. Therefore, the objective of this study is to elucidate the above differences between those with versus without involuntary urine leakage during the measurement of stress urethral pressure in women with USI.

Between July 2009 and December 2023, medical records, including urodynamic data, bladder dairy data and questionnaires, including patient perception of bladder condition (PPBC), urgency severity scale (USS), overactive bladder symptom score (OABSS), urogenital distress inventory (UDI-6), incontinence impact questionnaire (IIQ-7), and King's Health Questionnaire (KHQ), of all women with USI were reviewed to see if there was any involuntary leakage of urine during stress urethral pressure measurement.
STATA software was used for statistical analysis. The Wilcoxon rank sum test or the Chi-square test were used for statistical analysis, as appropriate. A p < 0.05 was considered statistically significant. Linear regression analysis was also performed with an adjustment of overactive bladder syndrome (OAB) to elucidate the real clinical and urodynamic associations about the leak during stress urethral pressure measurement.

A total of 481 women with USI were reviewed (Table 1). Except for the higher percentage of OAB and bladder oversensitivity, the percentage of stress urinary incontinence was similar in the leak and without leak groups (Table 1). 
Despite the fact that there was no difference in the PPBC, USS, OABSS, UDI-6, IIQ-7  and KHQ scores between the leak and without leak groups. However, the leak group has higher episodes of urgency, daytime frequency, incontinence, and nocturia derived from its 3-day bladder diary record, compared to the group without leak (Table 1). Furthermore, the leak group had a larger pad weight, a lower volume at strong desire to void, lower maximum urethral closure pressure, and a longer functional pressure profile length, compared to the group without leak (Table 1). 
Adjusted by OAB, the leak group still has higher episodes of urgency, daytime frequency, incontinence, and nocturia, lower volume at strong desire to void, a lower maximum urethral closure pressure, and a longer functional pressure profile length, compared to the group without leak (Table 2).

USI women with a leak in the measurement of stress urethral pressure have more severe objective lower urinary tract symptoms despite no subjective differences, compared to those without a leak. In addition, women with USI with a leak in stress urethral pressure measurement had a poorer urethral closure function and a smaller bladder capacity, despite a slightly longer functional profile length.

Women with USI with urine leakage in stress urethral pressure measurement appear to have more severe lower urinary tract symptoms, poorer urethral function, and smaller bladder capacity, compared to those without urine leakage.