On the initial nephrogram images, a large amount of uptake was noted in the right kidney (this is known as a "prompt nephrogram"); however, on the left side, a delay of uptake into the kidney parenchyma was observed (known as a "delayed nephrogram"). (Please note that the initial film obtained in the first minute of the nephrogram is not available.) A delayed nephrogram is pathognomonic for an obstruction. It does not, however, show exactly where the obstruction is located.
Figure 1, a 5-minute delayed film, demonstrated a persistent nephrogram in an enlarged left kidney and delayed excretion of contrast into a dilated collecting system; the right kidney appeared normal. In addition, on other delayed films (Figures 2 and 3), a massively dilated pelvicalyceal system with blunting of the calyces was noted on the left. A cut-off point at the ureteropelvic junction (UPJ) was also noted on that side, without visualization of the left ureter. All of these changes were consistent with localization of the obstruction to the UPJ on the affected side. The left ureter was not seen to opacify on the delayed films. The right pelvicalyceal system, however, was well-defined, and the calyces showed normal sharp cupping (Figure 2). The right ureter appeared thin or delicate, and a column of contrast was noted to reach down to the bladder; this ruled out any right-sided obstruction (Figure 2). The postvoiding film showed almost complete emptying of the bladder. By that point, the contrast had relatively cleared (with some residual contrast still in the collecting system) from the right kidney collecting system; the left side, however, was still full of contrast (Figure 3). These findings were consistent with a radiographically established UPJ obstruction.
The ultrasonography (images not available) in this patient showed dilatation of the left pelvicalyceal system, with hydronephrosis of the left kidney and thinning of the cortex. The right kidney and bladder were normal. No abnormalities were seen in the liver, gall bladder, pancreas, or spleen. A renal scan was also performed (images not available), which showed a nonobstructed right kidney with normal function. The left kidney showed hydronephrosis and impaired function suggestive of UPJ obstruction. The total glomerular filtration rate (GFR) was measured at 123.35 mL/min, with a right-kidney GFR of 69.33 mL/min (within normal limits) and a left-kidney GFR of 54.02 mL/min (below normal). The split functions of the kidneys were noted to be 56% for the right kidney and 44% for the left kidney.
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Cite this: Arun Phophalia, Madhu Phophalia. Fever, Pain, and Failure to Thrive in a 9-Year-Old Boy - Medscape - Dec 16, 2015.