The mechanism of congenital hydronephrosis with reference to the factors influencing surgical treatment.

THE MODERN TENDENCY towards conservative surgery in the treatment of hydronephrosis has aroused new interest in the problem of defining the primary cause of the idiopathic or congenital type of this disease. Early exploration of the condition is now common practice and provides an opportunity for the study of the pelvi-ureteric region before stasis and infection have rendered the renal pelvis inert and before the cause and the effect of the pelvic dilatation are largely confused. Such opportunity prompted these investigations into the dynamics of the upper urinary tract in congenital hydronephrosis and allowed for the movement patterns which were observed to be correlated with the gross and microscopic appearances of the pelvi-ureteric junction. The observations have been made upon thirty-five patients with hydronephrosis which could not be attributed to any definite cause such as calculus, tumour or lower urinary tract obstruction. A series of controls was obtained from seven patients who were subjected to nephrectomy for early renal disease, supplemented by specimens obtained from healthy pigs immediately after slaughter. The pig was chosen in support of the normal pattern because the musculature of its upper urinary tract is similar to that in man, and conducts the same average volume of urine each day. The movements of the intact renal pelvis and upper ureter have been studied during cinepyelography or at operation, and many of the pelviureteric segments which were excised either at nephrectomy or pyeloplasty were perfused in a physiological bath so that their contractions could be observed under controlled conditions. All the material has been examined histologically with particular reference to the arrangement of the muscle fibres at the pelvi-ureteric junction. It has obviously not been possible to apply all the techniques to each of the cases and statistics will not feature in any of the argument. The purpose of the lecture is to animate the pathology of congenital hydronephrosis and to demonstrate in terms of abnormal contractions those various aetiological factors which have previously been described.