ABSTRACT
The ureteropelvic junction (UPJ) is the most common site of obstruction in the pediatric upper urinary tract. The UPJ is formed during the fifth week of embryogenesis. Conditions associated with UPJ obstruction include imperforate anus, congenital heart disease, esophageal atresia, and the VACTERL association, as well as other urologic anomalies including contralateral multicystic dysplastic kidney, vesicoureteric reflux, and renal ectopia including horseshoe kidney. The anastomosis should begin at the caudal end, where the lower lip of the renal pelvis meets the spatulated apex of the ureter. The authors prefer the transperitoneal route for pyeloplasty as it provides a much larger working space and better ergonomics, especially for fine intracorporeal suturing. In horseshoe kidneys, the ureter often inserts high into the renal pelvis; a longer, more caudally placed anastomosis is needed. In some situations, the gap is too long to bridge by mobilizing the kidney and distal ureter.
