Abstract
With reference to a series of 13 patients, the urographic signs seen in the conditions of acute, post-acute, chronic and acute-on-chronic obstruction are described. These are seen in a relatively pure form in patients with renal failure due to ureteric calculi. Patients in renal failure with acute, post-acute, or acute-on-chronic obstruction are anuric or oliguric; patients with chronic obstruction due to bilateral ureteric stones are polyuric. After removal of the stones the urine output returns to normal in cases of acute obstruction, is reduced in chronic obstruction but is increased in post-acute obstruction. A further case is described which illustrates the importance of recognizing post-acute obstruction unaccompanied by pain: The kidney may be completely obstructed and so be destroyed. The different types of obstruction are recognized by considering the nephrographic and pyelographic signs together with the presence or absence of pain.