Introduction
A minority of women with a subjective complaint of stress urinary incontinence will have negative urodynamic stress incontinence (USI) findings.

Aim
To test clinical and ultrasound measures as predictors of an unexpected absence of USI. We hypothesised that unexpectedly negative USI would be more common in young women with good pelvic floor and urethral function.

Methods
A retrospective study analysing 398 data sets from women attending a urogynaecology clinic for evaluation of lower urinary tract and pelvic floor dysfunction. Clinical, urodynamic and translabial ultrasound data were tested as possible predictors of negative USI findings.

Results
Women with unexpectedly negative USI findings were younger, had less anterior compartment prolapse and had a higher maximum urethral pressure. Measures of pelvic floor muscle function were not predictive.

Conclusions
Women with unexpectedly negative USI are younger and have better urethral function, but voluntary pelvic floor muscle function seems unrelated to this phenomenon.