Ureteral pressure flow studies in difficult diagnostic problems.

Before a ureteral operation is undertaken for dilated, non-refluxing ureters it is essential to determine whether obstruction is present, since an operation is unnecessary and can be hazardous if there is no obstruction or infection. Obstruction is most accurately diagnosed by perfusing the upper tract at a known flow rate and measuring the resulting pressure. This test was performed on 5 patients in whom there was doubt as to the presence of obstruction from the radiographic evidence. In 4 of the 5 patients low pressure was found, the obstruction was excluded and an operation was avoided. In the fifth patient the obstruction was confirmed and relieved. The pressure flow test is useful in the diagnosis or exclusion of obstruction in the upper urinary tract.