The diagnosis of pelviureteric junction obstruction.

The distinction between a dilated upper urinary tract which is obstructed and a dilated but unobstructed system is of fundamental importance. This differentiation may be difficult to make with methods of diagnosis currently available. Standard intravenous urography provides good morphological information about the collecting system but is unreliable in the assessment of urodynamic upper tract function and renal parenchymal function. Pressure/flow studies may provide useful urodynamic information but the method has certain disadvantages. Standard probe renography is unreliable in differentiating upper urinary tract stasis from obstruction. A quantitative method of diuretic urography and a new quantitative gamma-camera renal radionuclide investigation are described and the results of these investigations are compared with urodynamic studies in patients with upper urinary tract obstruction at the level of the pelviureteric junction.