Pathophysiology of ureteropelvic junction obstruction. Clinical and experimental observations.

The preceding discussion has identified many of the frustrating difficulties in the definition, diagnosis, and determination of the significance of obstruction in hydronephrosis. Unfortunately, doubts have been raised about the indications for surgical intervention, which is so often needed to prevent renal deterioration. Are the newer diagnostic tests seriously flawed; should we be relying more heavily on anatomic studies such as intravenous and retrograde pyelography and operating purely for pelvic enlargement and characteristic radiographic appearances? Absolutely not. All upper urinary tract (ureteropelvic) obstructions are not the same. Obstruction is not a single disease process, and its outcome cannot be predicted purely by anatomic appearance. Most cases of suspected obstruction are straightforward, and the correct diagnosis can be arrived at easily, but the difficult cases remain a diagnostic challenge. In these, we must use newer diagnostic tests freely but not merely as triggers for surgical intervention; they are not that accurate. Instead, they should be used to obtain as much physiologic information as possible to help categorize the suspected obstruction and predict its potential for obstructive injury. Only in this way can we hope to prevent progressive renal deterioration and to ensure that surgical reconstruction is both necessary and effective.