Paediatric Imaging

Hydronephrosis

increase in size of the renal collecting system. It is often associated with hydroureter. Increase in size of the renal pelvis and calyces is most commonly caused by partial or complete obstruction at pelviureteric junction (PUJ). This is usually congenital in nature and can be caused by an aberrant renal vessel or intrinsic abnormality at the pelvic ureteric junction. The renal pelvis often bears the brunt of the dilatation being relatively more distended than the calyces although the amount of calyceal dilatation in all forms of PUJ obstruction is variable. Vesicoureteric junction obstruction causes ureteric dilatation as well as hydronephrosis. Bladder neck or urethral obstruction can cause hydronephrosis due to reflux. Bladder wall thickening in posterior urethral valves can also cause obstructive hydronephrosis. Hydronephrosis can also be caused by vesicoureteric reflux. Presenting symptoms are most commonly abdominal pain, loin pain, urinary tract infection or an abdominal mass.

The functioning renal cortical mass may be well preserved or extremely thin. Ultrasound is the means of demonstrating renal size, renal cortical thickness and the degree of pelvic and calyceal dilatation. Many cases of hydronephrosis are first seen in utero. Excretory urography will demonstrate the renal cortex and degree of calyceal and pelvic dilatation as long as function is reasonably preserved. Delayed films may be necessary to allow contrast to accumulate within the calyces and to demonstrate the collecting system appropriately. If function is reasonably preserved isotope renography with diuretic enhancement will quantify renal function and the degree of obstruction. Reflux can be confirmed by micturating cystourethrography or radionuclide cystography.

DWP