Ultrasound images of The duplex system pediatric

The duplex system is one of the more common congenital anomalies, occurring in up to 9% of referrals.14 It stems from aberrant budding of the Wolffian duct in utero, and can take a variety of forms, from complete duplication with two kidneys, each with a separate ureter, to a partial duplication involving the kidney only. Complete duplication predisposes to reflux, particularly into the lower moiety and subsequently to infection. The upper pole moiety of a duplex kidney is more prone to obstruction either secondary to a ureterocoele or, less commonly, with an obstructed ectopic ureter. In the former case the obstructed upper moiety may be associated with a dilated ureter which can be followed to the bladder where a ureterocoele, that is, a cystic dilatation of the distal ureter, may be seen within the bladder at the ipsilateral vesicoureteric junction (Fig. 9.5 B, C and D). The ureterocoele may extend into the urethra, causing bladder outlet obstruction which, if severe, may result in bilateral hydronephrosis. In the absence of any dilatation, it may be difficult to demonstrate the duplex kidney on ultrasound. Generally, the kidney is longer than normal and two discrete, hyperechoic sinus echoes can be seen. Ectopic insertion of the upper pole ureter in a duplex system is a cause of urinary incontinence in girls. It may not be possible to follow an ectopic ureter to its distal end, even
when dilated, but one may be able to demonstrate that the ureter is passing distally to the bladder.

Ultrasound images Normal neonatal kidney, showing lobulated outline, hyperechoic cortex, increased corticomedullary differentiation and reduced renal sinus echoes.