L’EtioIogie du reflux congenital et du méga-uretère primaire

Abstract

L’absence de reflux vésico-urétéral est normalement assurée par la tonicité de la musculature urétéro-trigonale dont nous décrivons l’anatomie. Ce mécanisme anti-reflux n’est pas uniquement un phénomène passif dû à l’action valvulaire de l’uretère sousmuqueux. L’altération ou l’insuffisance de la musculature urétérotrigonale conduit au reflux. L’étude histologique systématique de l’uretère terminal dans 30 cas de mégauretères primaires congénitaux, sans obstruction mécanique évidente, a démontré que la dilatation progressive est secondaire à une obstruction fonctionnelle de nature tissulaire: il s’agit le plus souvent d’une hypertrophie du tissu collagène ou du tissu musculaire ou encore de dysembryoplasies de la paroi urétérale; le méga-uretère congénital primaire n’est pas secondaire à une insuffisance ou une absence de cellules ganglionnaires parasympathiques comme on l’a cru longtemps.

Ultrastructural Characteristics of Collagen Tissue in Normal and Congenitally Dilated Ureter

“…In the narrow segment of the primary obstructive megaureter our findings agree with previous observations and with the concept of functional obstruction [2,5,9,10]. In the dilated portion, hypertrophic muscle generates a circular peristaltic wave which does not include the ure teral lumen, resulting in continuous urinary stasis and dilatation.…”

“…These elements combine in various forms and proportions to fulfil the functional needs of different organs [4], In the ureter, collagen forms a fibroproteinic structure among which the muscle bundles are found. Collagenous proliferation has been described in the ureteral wall of primary obstructive megaureter, refluxing megaureter and congenital ureteropelvic junction obstruction [2,3,[5][6][7], were obtained from 8 primary obstructive megaureters and 23 refluxing megaureters.The specimens were fixed in 5% glutaraldehyde in Milloning buffer. Transverse and longitudinal sections were prepared from each specimen.…”

La jonction urétéro-vésicale

“…From the functional standpoint, the propulsion of urine through the transparietal part of the ureter is dependent on the contraction of the circular and oblique muscle fibers lying in the immediately prevesical part of the ureter and is a direct function of the compliance of the terminal ureter. A frequent finding in cases of "primary" megaureter is the modification of the structure of the terminal ureter due to an increase of its connective tissue component [1,8,18,19,34,49,55]. These conditions lead to a disruption of the muscle nexus and decreased compliance of the terminal ureter.…”

Ultrasonographic anatomy and diagnosis of fetal uropathies affecting the upper urinary tract

“…These signs should allow one to distinguish this syndrome from obstruction distal to the bladder wherein the urinary tract dilatation is harmonious [Figs. 52,53,55,59]. Megalocystis is a practically constant finding in prune-belly syndrome (24/25 cases).…”

“…Its pathogenesis is a subject of debate [53,111]. An increase of the connective component of the terminal part of the ureter has often been found in primary megaloureter.…”