thesis
Resistive Index in Obstructive Uropathy
- Publication date
- 3 March 1999
- Publisher
- The diagnosis of urinary tract obstruction is a difficult and
perplexing problem particularly in children. Pyelocalyectasis is seen not
only in obstruction but also in other conditions, such as residual
dilatation afler relief of obstruction, vesicoureteral reflux and
pyelonephritis. Grey-scale ultrasonography is of little value in this
clinically impOliant distinction. The standard excretory urography
(IVU), even with diuretic augmentation, does not permit the objective
diagnosis or exclusion of urinary tract obstruction. The Whitaker test is
considered by some authors to be the gold standard for the diagnosis of
obstructive pyelocalyectasis but it is invasive and therefore has not
gained wide use. Moreover, the intrinsic urine output of the kidney
contributes an unknown volume to the total amount of fluid being
infused, particularly in children, and the potential for false-positive
results should be considered whenever the urine output of the
corresponding kidney is high. Finally, the results are not always
reproducible or consistent with surgical findings.
Nowadays, diuretic renography is the most widely accepted
non-invasive procedure to diagnose obstruction. However, it has the
disadvantages of being expensive, using ionising radiation and having a
10% -15% rate of false-positive and indeterminate results (Kass et aI.,
1985). Magnetic resonance imaging (MRI) (Thumher et aI., 1989) and
various biochemical indicators of the response of the kidney to
obstructive damage (Carr et aI., 1994) have recently been investigated.
However, the clinical significance of such new approaches remains to be
determined.