Roentgen evaluation of distal urethral obstruction.

Abstract

Distal urethral obstruction by definition is a pathological diminution of the lumen or of the distensibility of this canal. About 20 per cent of urologic disorders in children are stated to be congenital stenosis of the urethra, with most of them located at the meatus (3). Tudor and his associates (11) declare this the most common obstruction in the male child, whereas Burns et al. (1) and Keitzer and Benavent (6) judge the occurrence equal in both sexes and often overlooked in little girls. Burrows, using micturition cystourethrography, found meatal stenosis in 44 girls and 2 boys in a total of 496 children (2). Inspection, bougie calibration, and roentgenology are employed to detect meatal stenosis, and its diagnosis has become quite popular (2), so much so that Heslin (5) recommends routine calibration in children being circumcised or undergoing tonsillectomy. Knappenberger (7) advises that systematic interval urethral dilatations prevent infective urethral stenosis or stricture and have definite clinical value in the treatment of recurrent urinary tract infections in girls. Roentgen features considered indicative of meatal stenosis are urethral dilatation, meatal narrowing, and splaying of the opaque material after it has passed through the meatus. Lyon and his co-workers (8, 9) call attention to another type of urethral obstruction in females which they describe as distal urethral stenosis. They find this in 90 per cent of little girls with recurrent urinary tract infections. Bougie à boule calibration is indicated as necessary to detect the lesion in some patients, but they also describe four roentgen patterns of this type of obstruction in which the distal urethral segment shows narrowing of 0.5–1 cm, with or without dilatation above it. Doubt of the validity of the roentgen features of meatal and distal urethral stenosis arose in our experience because of (a) a lack of normal standards of urethral caliber and (b) the presence of these features in children in whom inspection and urethral calibration obviously showed no obstruction. Furthermore, there were children in whom meatal stenosis or distal urethral stenosis was diagnosed by inspection and/or bougie calibration, but without the roentgen features of such obstruction, or forced and intermittent voiding, bladder trabeculation, vesicoureteral reflux, or documented urinary tract infection. Therefore, a study of the distal urethra was undertaken to establish normal standards and to evaluate the roentgen features considered diagnostic of meatal and distal urethral stenosis. The purpose of this communication is to report the results of this study. Material Voiding cystourethrography was performed in 478 children, 287 females and 191 males.