Appendix graft as a ureter substitution in recurrent ureter stenosis in horse -shoe kidney; a case report

A horseshoe kidney is the most common renal fusion anomaly and occurs in 0.2% to 0.3% of the population. Horseshoe kidneys are fused by the formation of an isthmus between the lower poles of the left and right kidneys during development. The insertion of the ureter in the renal pelvis is displaced super-laterally, probably as the result of incomplete renal rotation, and is associated with a significant rate of ureteropelvic junction (UPJ) obstruction.
We report a patient with single kidney at right side with obstruction in upper ureter. Before the surgery our plan was transureteroureterostomy according to failure of previous surgeries, dismembered pyeloplasty and ureterocalicostomy, but after mobilizing the proximal ureter we noticed that transureteroureterostomy was impossible because of short fibrotic ureter. Other choices such as Boari flap technique with psoas hitch is impossible because of small fibrotic bladder, so we decided to use appendix as ureter substitute.
According to our experience and previous studies, we can use appendix as a ureter substitution in refractory proximal and middle ureter stenosis, but in our case we anatomized proximal ureter to appendix instead of anastomosis of pelvic to appendix.