3. Whitaker, R. H.: Equivocal pelvi-ureteric obstruction. Brit. J. Urol., 47: 771, 1975. 4. Kesavan, P. and Fowler, R.: Vesicoureteric reflux and ureterovesical obstruction. Urology, 10: 105, 1977. 5. Whitaker, R. H.: Reflux induced pelvi-ureteric obstruction. Brit. J. Urol., 48: 555, 1976. 6. Whitaker, R.H.: Urodynamic assessment ofureteral obstruction in retroperitoneal fibrosis. J. Ural., 113: 26, 1975. EDITORIAL COMMENT The contributions in this evaluation and subsequent management of patients with distortion of the collecting systems are real ones.
However, the question still remains whether obstruction always is a static one or whether there is not an intermittency to some situations of hydronephrosis. I wonder if, on occasion, a situation requiring ultimate repair might not be delayed unduly if the pressure flow studies were applied at the time of normalcy of outflow. LP. REPLY BY AUTHOR Undoubtedly, there is the occasional intermittent hydronephrosis in which obstruction cannot be precipitated by this method. We find that only an IVP during an attack of pain will then give the diagnosis. This exception detracts little from the obvious advantage of a dynamic approach to the problem of upper tract obstruction.