Obstructive vs nonobstructive dilatation of the renal collecting system in children: distinction with duplex sonography.

Resistive indices in the evaluation of infants with obstructive and nonobstructive pyelocaliectasis.

“…8,23 359 However, using dual criteria of an RI greater than 0.7 and a DRI = 0.08 between kidneys, Kessler and coworkers found a positive predictive value of 95% and a negative predictive value of 100% in the diagnosis of obstruction. 11 A limitation of their study was that they did not mention how many of their 36 children with hydronephrosis were infants. Gilbert and colleagues used the discriminatory criteria of RI = 0.7 in 28 kidneys with pyelocaliectasis; 60% of their 26 children were 1 year old or younger.…”

“…However, it can be fallible under certain circumstances. 11 The sensitivity and specificity of the Whitaker test for diagnosing obstructive uropathy are 93 and 91%, respectively. 13 The diuretic renal scan that has replaced in most cases the invasive Whitaker test may yield false-positive results if the diuretic is administered before maximal filling of the collecting system, if the kidney does not respond adequately to the diuretic, if bladder drainage during the study is inadequate, or if renal function is compromised.…”

“…Review of the literature also shows that sensitivity and accuracy of Doppler sonography for diagnosing obstructive uropathy not only depends upon whether RIs of obstructed kidneys are compared with normal kidneys or nonobstructed kidneys with pyelocaliectasis but also on whether IVP, Lasix renography, the Whitaker test, or surgery is used as a gold standard for diagnosing urinary obstruction. 4,5,[11][12][13][14][15]22,23 Once pyelocaliectasis is identified by conventional gray scale sonography, further studies are needed to establish the diagnosis of urinary obstruction. However, no reliable diagnostic gold standard exists for diagnosing obstructive uropathy.…”

“…However, using the same adult criterion of an RI of 0.7 or greater, Kessler and colleagues documented high sensitivity (95%) and specificity (85%) in 36 children under 20 years old, 11 and Gilbert and associates in a study of 26 children 10 years old or younger with unilateral hydronephrosis obtained a 100% sensitivity and 85% specificity in the diagnosis of urinary obstruction. 12 We undertook a prospective study of infants with significant pyelocaliectasis to evaluate the accuracy of the RI in the differentiation of obstructive from nonobstructive uropathy and to select an appropriate threshold for the detection of urinary obstruction in this population.…”

“…[4][5][6][7] Renal RIs are normally higher in children compared to adults up to the age of 10 years, with the highest values in infants under the age of 1 year. [8][9][10][11][12] Received October 17, 1998, from Loyola University Medical Center Diagnosing obstructive uropathy by renal resistive indices calculated from duplex Doppler sonographic waveforms has been supported as well as challenged in the radiology literature relating to adults. Despite reports of normally higher resistive indices in children as compared to adults, two studies have documented high sensitivity and specificity of renal Doppler sonography in the diagnosis of obstructive uropathy in children, using the same discriminatory criterion of a resistive index of 0.7 or greater as used in adults.…”