STUDY OF THE ARTIFACTS INDUCED BY LINEAR-ARRAY TRANSVAGINAL ULTRASOUND SCANNING IN URODYNAMICS

In patients with incontinence problems, endovaginal urodynamic ultraso nography is a technique which easily complements manometric examinatio n by permitting a precise study of peri-urethral soft tissue. Use of a linear array probe under standardised conditions gives, at present, t he best results. To validate the technique, it is, however, important to understand the artefacts it provokes. Thirty-four patients underwen t urethral profilometry at rest and during effort with and without the ultrasonographic probe. In the patients studied, none of the classica l urodynamic parameters were modified. However, in cases of narrow vag inas (distance between the arcuate ligament and the ultrasonographic p robe less than 12 mm), a small increase in the maximum urethral closur e pressure (5 cm H2O) could be observed. The angle between an intra-ur ethral cotton swab and the horizontal plane was measured at rest and d uring maximum coughing effort, both with and without the ultrasonograp hic probe. A significant reduction of the angle was observed at rest a nd during effort. However, since linear regression is particularly eff ective in modelling these two artefacts (R2 = 0.8 and 0.7), they can b e considered as constants and are not bothersome in clinical practice. Abdominal ultrasound was used in 10 patients during the introduction of the endovaginal ultrasonographic probe to study its impact on the b ase of the bladder. A clear increase in the posterior urethro-vesical angle was observed, which was shown to be a function of the degree of probe insertion in the vagina. As this artefact was variable and could not be controlled, this angle should no longer be measured using this technique. Linear endovaginal ultrasonography does perturbe vesico-ur ethral anatomy, but not in a way problematic to the clinician. It does not provoke significant compression phenomena, but does compromise me asurement of the posterior urethro-vesical angle. Despite this, it rem ains a good complement to urodynamic examination.