Ultrasound Study of the Ureters and Intrarenal Excretory Tract

Fig. 16.1

A stone in the subjunctional tract of the right ureter

Fig. 16.2

A stone in the lumbar tract of the left ureter. The ureteral ectasia continues beyond the stone (possible distal obstruction)

Fig. 16.3

Ultrasound study with diuretic test of the right ureter, secondary to a ureteral stone that is mobile inside the lumen. The patient underwent right ureterocystoneostomy with reimplantation of the ureter on the bladder dome and stenosis of the anastomosis

Fig. 16.4

Twinkle artifact, a stone in the left lumbar ureter

Ureteral malformations that can be seen with ultrasound scanning include:

Megaureter
Ureterocele
Duplication of the upper urinary tract (a duplex renal district)
Retrocaval ureter

In megaureter the ultrasound picture is generally aspecific, consisting of ureteral ectasia, associated or not with dilation of the pelvis and calyces. An ectatic ureter that suddenly narrows about 2–3 cm before the ureteral ostium is indicative of megaureter (Fig. 16.5).

Fig. 16.5

Picture of a megaureter in a pediatric patient, showing marked ureterohydronephrosis with narrowing of the terminal ureter about 3 cm from the ostium

By contrast, the ultrasound picture of ureterocele is surely diagnostic, showing a rounded transonic mass outlined by a thin echogenic wall, at the level of the ureteral ostium and protruding into the bladder lumen. In an ultrasound study of ureterocele, it is helpful to assess the bladder with only moderate-minor filling because if it is too distended, it could mask the ureter itself. Variations in the voIume of the ureterocele will be evident during ureteral peristalsis. There may be a concomitant ectasia of the entire upper urinary tract. Ureterocele may frequently be associated with a duplex upper urinary tract (ectopic ureterocele) often affecting the upper and less frequently the lower hemidistrict (Fig. 16.6).

Fig. 16.6

Right ureterocele

As regards the presence of a duplex upper urinary tract, ultrasound has poor sensitivity unless there is ectasia. Elements that may raise the suspicion of a duplex district are an enlarged kidney, with a complete parenchymal septum at the level of the median third or at the limit between the median and the superior third. Often there is a marginal groove at the level of the septum, and color Doppler will sometimes show a duplicated vascular pedicle. If the system is ectatic, a transonic mass can be seen at the upper pole of the kidney, due to ectasia of the upper district, from which the dilated ureter can be seen to emerge, often with an ectopic ostium (bladder neck, proximal urethra) (Fig. 16.7).