[The physiopathology of vesicoureteral reflux (author's transl)].

The tightness of the ureterovesical junction depends on all the structures composing the terminal and intra-mural ureter. The muscular, collagenic, and elastic fibers of the ureter constitute a mesh net which is stretched during bladder distention and closes the ureteric orifice as a valve. Congenital vesico-ureteric reflux results from a primary structural insufficiency of the terminal ureter or insufficiency of the bladder wall backing. As embryology shows primary reflux can be caused by a high ectopic implantation of the ureter. It results from the development of an ureteric bud appearing in a lower than normal position on the Wolffian duct. This results in a higher and more lateral opening of the ureteric orifice in the bladder which leads to a shorter intra-mural tunnel predisposing it to reflux. Secondary or acquired refluxes are associated with chronic obstructions (i.e. neurogenic bladder--lower urinary tract obstruction), and inflammatory lesions. Their pathogeneses are described and discussed. The maturation of the ureterovesical junction is considered a mechanism involving a reduced likelihood of secondary reflux. It may also, during the first years of life, palliate some minimal structural deficiencies of the intra-mural ureter, but growth and development are unlikely to normalize an ureter presenting at birth with a severe constitutional anomaly.