Urethral pressure reflectometry vs urethral pressure profilometry in women: a comparative study of reproducibility and accuracy

Objective To compare urethral pressure reflectometry (UPR), a new and simple technique for simultaneous measurements of cross-sectional area (CA) and pressure in the female urethra, with urethral pressure profilometry (UPP). Patients, subjects and methods The study included 143 women (105 patients and 38 healthy volunteers); the UPR was measured using a very thin polyurethane bag in the urethra; a pump applied pre-selected pressures stepwise to the bag and for each step the CA was measured by acoustic reflectometry. Measurements were made during both inflation and deflation. The women were examined supine both while relaxed and during 'squeeze', and while upright and relaxed. The following variables were measured; the opening and closing pressure, the opening and closing elastance and the hysteresis. For UPP we used the perfusion technique with the patient supine and relaxed. All the women were assessed twice with both UPR and UPP at the same setting (short-term reproducibility) and 17 patients were assessed with both methods on two different days (long-term reproducibility). Results The mean pressures were 51.7 and 52.9 cmH(2)O for the UPR and UPP, respectively (not significant) at a CA of 5.1 mm(2); the limit of agreement between the methods was -19.4 to +17.0 cmH(2)O (mean and 2 SD). The Pearson coefficient was - 0.16 (not significant). The variability (2 SD) of two consecutive measurements was significantly less with UPR (9.5 cmH(2)O) than UPP (13.8 cmH(2)O; P < 0.001). For the opening and closing pressures the coefficient of variation (CV) was 5.9-11.6%; for the elastances the CV was 14.3-31.2% and for the hysteresis the CV was 12.9-49.1%. In test-retest measurements, the variability of the UPR values (2 SD, 8.7 cmH(2)O) was significantly less than for UPP (15.4 cmH(2)O; P < 0.05). The discomfort of UPR was statistically less than for UPP or than a standard gynaecological examination. Conclusions Compared at the same CA, UPR measured the same pressure as UPP but the UPR was more reproducible. With the patient relaxed the opening and closing pressure, opening and closing elastance and the hysteresis can be measured while supine and upright; while squeezing, the opening pressure and elastance can be measured.