Urethral pressure profile:: Is it affected by position?

The aim of this study was to investigate the difference between sitting and standing passive urethral pressure measurements, and to determine the accuracy of urethral pressure profilometry in each position. Urethral pressure profilometry was performed in the sitting and standing position in 98 women. Stress incontinence due to urethral sphincter incompetence was demonstrated in 59 of whom 6 also had detrusor instability. The others were normal volunteers (7), women with a normal cystometrogram (23), and women with detrusor instability (9). MUCP tended to be higher in the standing than the sitting position but this did not reach statistical significance. Urethral lengthening appeared to occur on standing with a mean increase of FUL of 5 mm on standing. For both FUL and MUCP, there was a wide variation in the difference between sitting and standing values. There was poor reproducibility of measurements of MUCP and FUL in the standing position, limiting its clinical applicability. The difference between sitting and standing MUCP and FUL was not affected by age, parity, weight, height, BMI, or oestrogen status. In women with genuine stress incontinence, there was less difference between sitting and standing MUCP, but this explained only a small part of the variability. The increase in FUL in the standing position was unaffected by diagnosis.