Ureteropelvic Junction Obstruction
A ureteropelvic junction or UPJ obstruction is a narrowing of blockage at the point where the kidney meets the ureter.
This condition can be congenital or can be caused by stones or prior surgery. If it is congenital, it may be that a segment of the ureter is narrow or the muscle does not form correctly so urine does not flow, or it may be caused by a blood vessel crossing over the UPJ.
UPJ obstruction may cause abdominal or flank pain, especially after drinking a large volume of fluids as this causes stretching and dilation of the kidney. It may also lead to the development of kidney stones, infections, or even kidney failure from chronic obstruction.
UPJ obstruction can be treated by the placement of a ureteral stent, by a ureteroscopic procedure called an endopyelotomy, or by performing a pyeloplasty. During a pyeloplasty, which is often performed laparoscopically or robotically, the narrowed segment of ureter is resected and the healthy edges are sutured back together to relieve the obstruction.