抄録
One hundred and thirty-seven unilateral kidneys of 70 children (ranging from 6 months to 15 years old) were examined sonographically with a water load stress test with diuretics administration. The renal regions were scanned longitudinally and transversely. The maximum AP (antero-posterior) diameter of the renal pelvis with transverse views of the kidney was recorded. Scanning studies were performed three times in each child as follows, the first scan was done 30 minutes after oral water load, the second scan, about 30 minutes after oral administration of diuretics (furosemide 0.5 mg/kg). After the second scan children were forced into urination. The third scan was performed about 10 minutes after urination. The variations of the AP diameter of the renal pelvis in three different conditions were observed. Nineteen unilateral kidneys of 18 children whose diagnosis of upper urinary tract obstruction was made by intravenous urograms (IVUs), renograms with diuretics and clinical course had a positive response to a simple water load and a water load with diuretics. The increasing rate of the renal pelvic AP diameter of 19 renal units after diuretics administration ranged from. 21% to 114% (mean 58%) and was significantly high compared with non-obstructive renal units. Of 19, renal pelvic AP diameter of 6 renal units in which the increasing rate was less than 50% exceeded 20mm after administration of diuretics, despite the relatively low increasing rate. The renal pelvic AP diameter of those obstructive renal units remained unchanged or increased after urination. The renal pelvic AP diameter of 69 normal renal units in IVUs did not exceed 10mm after a water load without diuretics and of 69, those of 3 renal units exceeded 10 mm after a water load with diuretics.
Sonographic evaluation of upper urinary tract obstruction using a water load stress test with diuretics administration was as follows: the renal unit filled with the following 1) or 2) condi-tions may be upper urinary tract obstruction (sensitivity 95%, specificity 98%, accuracy 97%).
1) The AP diameter of the renal pelvis should exceed 10mm after hydration without diuretics and simultaneously the increasing rate of the renal pelvic AP diameter should be more than 50%; there should be no decreasing of AP diameter after urination.
2) The renal pelvic AP diameter should exceed 10 mm after a simple water load, if the increasing rate of the renal pelvic AP diameter is less than 50%, the AP diameter should exceed 20 mm after hydration with diuretics and there should be no decreasing of AP diameterafter urination.
The renal sonography in a water load with diuretics is an indispensable functional screening test to examine patients who are suspected of suffering from obstructive uropathy and are placed on the post-operative follow-up study. This method proved to be one of the most versatile techniques for patients who undergo frequent invasive techniques in the course of a clinical follow-up as this technique remains non-invasive and causes fewer clinical symptoms.
