Ultrasound-estimated bladder weight in healthy children.

Bladder weight in healthy children was determined ultrasonographically using a modified formula that takes into account the different shapes of the urinary bladder. Ultrasonographic examination of the bladder was performed on 92 healthy children (56 boys, 36 girls) with a 5-MHz transducer. Bladders were categorized into five groups according to shape, and three bladder diameters were measured. Ultrasound-estimated bladder weight (UEBW) was calculated according to the formula modified for bladder shape. Correction coefficients were used: 0.55 for round shape, 0.79 for ellipsoid, 0.92 for cuboid, 0.62 for triangular, and 0.78 for undefined shape. Twenty-three children had a round bladder (25%), 22 cuboid (24%), 21 ellipsoid (22.8%), 25 triangular (27.2%), and 1 child had an undefined bladder shape. Using linear regression analysis, a formula was derived for the calculation of normal values of the UEBW by age: UEBW (in grams) = A x 0.995 + 8.405 ( A=age in years). For simplicity in clinical use, the formula was modified to UEBW= A + 8.4. A statistically significant correlation was observed between UEBW and age ( r=0.78, p<0.05). UEBW correlates significantly with children's age. This simple formula is proposed for noninvasive calculation of normal UEBW by age that may be used for the objective and quantitative assessment of the degree of bladder wall hypertrophy. Further studies are needed to evaluate the potential of this method in the detection of pathological bladder conditions.