NONINVASIVE EVALUATION OF BLADDER COMPLIANCE IN CHILDREN USING ULTRASOUND ESTIMATED BLADDER WEIGHT

Purpose: In healthy children as well as those with urinary disturbance we determined ultrasound estimated bladder weight with the aim of rev ealing its possible usefulness as a measure of bladder compliance. Mat erials and Methods: We measured ultrasound estimated bladder weight in 71 healthy children with a mean age of 10.3 years, and determined a s tandard value. A total of 82 patients with a mean age of 9.6 years wit h urinary disturbance also underwent ultrasound estimated bladder weig ht measurement as well as conventional urological examinations, includ ing filling cystometry. Results: In healthy children ultrasound estima ted bladder weight increased with age, showing a significant linear co rrelation (r = 0.80, p <0.0001). Using the formula for linear correlat ion, 0.86 x patient age + 6.9 gm., we obtained an age matched estimate d weight. In 82 patients the percent deviation of the estimate from ag e matched values was calculated using the formula, (measured ultrasoun d estimated bladder weight -age matched ultrasound estimated bladder w eight)/age matched ultrasound estimated bladder weight x 100, and then correlated with bladder compliance. In 75 of 77 patients (97%) with c ompliance of 10 ml./cm. water or more the estimate was within 100% dev iation. In contrast, 4 of 5 patients (80%) with a low compliant bladde r (less than 10 ml,/cm. water) had an ultrasound estimated bladder wei ght greater than 100% deviation. When the estimate was within 100% dev iation, all but 1 patient (75 of 76, 98.7%) had compliance of 10 ml./c m. water or more compared to 33.3% (2 of 6) of those with an estimate greater than 100% deviation. As a result, with the use of a cutoff val ue of 100% deviation ultrasound estimated bladder weight predicted a l ow compliant bladder with a diagnostic accuracy as high as 96.3% (79 o f 82 cases).Conclusions: Ultrasound estimated bladder weight may be us ed to evaluate bladder compliance in children. It seems to be a suitab le noninvasive urodynamic test in children with suspected urodynamic a bnormalities.