Bladder neck mobility evaluated by vaginal ultrasonography.

Factors involved in monitoring bladder neck mobility were studied by means of vaginal ultrasonography. Thirty-three continent, 28 incontinent and 39 patients who had undergone surgery for incontinence were examined in the supine and sitting positions during rest, the Valsalva manoeuvre and withholding urine. Bladder neck mobility can be described as a semicircular movement with the tip of the symphysis pubis as the centre and a line from the tip to the bladder neck as the radius (BS). Movement can be measured by 2 independent factors: BS distance and size of the angle between the BS line and the midline of the symphysis, at rest, during the Valsalva manoeuvre and withholding urine. The continent controls were characterised by a 90 degrees angle at rest, a long BS (2.4 cm) and a fixed bladder neck. The incontinent patients had a shorter BS (2.1 cm), angles at rest of approximately 100 degrees--the angle increased with the grade of incontinence--and a mobile bladder neck. If 2 of the 3 criteria (angle at rest > or = 95 degrees, BS < or = 2.3 cm and mobility > or = 20 degrees) are regarded as diagnostic of incontinence, diagnostic sensitivity was 84% and specificity 82%. In the surgical group, patients who failed to respond to treatment had a shorter BS, larger angles and greater bladder neck mobility than their successfully treated counterparts.