Investigations are required to diagnose and know the severity of damage to the entire urinary system and must be carried out regularly and completely. The main radiological investigations are an Ultrasonography(USG) for kidneys ureters and bladder and a Voiding Cysto Urethrogram (VCU).

USG will show a large dilated bladder, thickening of the walls will suggest long standing and severe obstruction, there may be outpouchings called diverticuli that are diagnostic of severe obstruction. With bad obstruction, the ureters will also be dilated, elongated and tortuous filled with urine. The kidney pelvis will also be hugely dilated with a thinning of the parenchyma of the kidney, all this on one or both sides. This investigation does not give any idea of function only the dimensions and appearance of the organs being looked at. Bilateral dilated upper tracts prove an obstruction distal to the bladder and in boys the commonest is PUV.

Sonography of 2 patients with Valves

VCU - is the next investigation wherein a small tube is passed into the urethra of the child upto the bladder and the bladder is filled with a contrast liquid that is seen as white on a x ray picture. When the bladder is full one x ray is taken to look for the shape, size of the bladder. The distorted shape of the bladder with multiple outpouchings may be seen, there may or may not be a secondary reflux of urine from the bladder into the ureter(s) as described in Urinary Reflux chapter. Next the tube is removed from the bladder and the child is asked to pass urine and a second x ray is taken as the child is passing urine. This is the most important picture - this will show a dilated posterior urethra proximal to the valves, described as pear shaped; the valves are seen as negative shadows in the center of the urethra beyond which the urethral caliber is narrow. Reflux not previously seen may be now visualized on one or both sides. A third picture is taken after the child has passed urine and may show incomplete evacuation of the urine and residual contrast in the bladder.

Voiding Cystourethrogram of patients, left shows reflux in both ureters, right shows no reflux. Both show dilated urethra (yellow arrow) and small irregular bladder(white arrow)

Besides the radiological investigations routine blood tests including those to check the function of the kidneys are done to know the state of the kidneys at the time of diagnosis - but this will give only an overall picture of normal function of both kidneys together not individual ones. For this another radiological study - Radio Nuclear DTPA Scan of the kidneys is done. Here radioactive contrast is injected in the vein of the boy and pictures of the kidney are taken at intervals. This investigation will give exact individual percentile function of the kidneys, it will also show the obstruction in the bladder as well as a secondary one at the junction of the ureter and bladder if present. This can be used as a baseline study for serial scans after therapy to show an improvement of the percentile function of the kidneys. Other investigations are done t look for the complications associated with this entity - like electrolyte imbalances and infection of urine and also in the blood stream by sending both blood and urine for Culture studies and treating the infection first before specific therapy for the PUV.