Precise urodynamic assessment of meatal and distal urethral stenosis in girls

Pressure/flow studies of micturition and urethral calibration have been carried out in some 100 girls, mean age 8.5 years, suffering from enuresis and/or recurrent urinary tract infections. By means of special urodynamic methods, including micturition with a thick urethral catheter that exaggerates the effect of urethral narrowing, a urodynamic caliber can often be assigned to any anatomic narrowing. This urodynamic caliber is closely related to the distal urethral or meatal caliber obtained with the bougie A boule, showing that both are measures of the same narrowing. In 68% of the girls the distal urethra and meatus are so wide that there is no urodynamically detectable obstruction even when the thick (8 FG) catheter is present. When the effect of the catheter is allowed for, only 3.5% of the girls show real anatomic obstruction, a further 7% being borderline. In our material the few urethras with a bougie a boule calibration of 14 FG are all urodynamically obstructed, and those calibrating at 16 FG are sometimes so. It has previously been shown that in this group of stenoses the results of dilatation are better than average, supporting the conclusion that a real anatomic obstruction has been relieved.