[Unrecognized ureteral duplication (author's transl)]

The occult ureter in a duplex kidney should be recognized during the procedure time even if the intravesical orifice has not been visualized. In the opposite case it is possible to do some therapeutic errors. That is the reason why the authors report four new cases with five occult ureters in a duplex kidney. One is diagnosed during a second procedure for removing a stenosis on an unfortunate reimplantation with an acute renal failure. Four occult ureters were found during an intervention for a vesicorenal reflux on the functional ureter. The upper pouch was blind without any renal parenchyma in three cases and in two cases there was a little renal dysplasic parenchyma. In the four ureters where we have been able to observe the down pouch we have not seen an orifice in three cases and in one case the orifice was in ectopic position. Commentaries are done about the clinic context the similarities between this unrecognised ureter and ureterocele. Therapeutic approach is precised with the interest of an opacification during the procedure of all supplementary conduct discovered while the dissection of an ureter.