Ureteropelvic junction obstruction
 Discussion of Ureteropelvic junction obstruction
- Ureteropelvic junction obstruction (UPJO) is defined as functional or anatomic obstruction to urine flow from the renal pelvis into the ureter at their anatomic junction.
- If left untreated, results in symptoms, renal damage, or both.
- UPJO generally implies a congenital partial proximal ureteric obstruction detected in utero or in later life.
- The ureterovascular tangle is a term that embraces the renal pelvis, ureter, and adjacent vessels (both arterial and venous), all of which alone or in combination have been implicated as potential causes of UPJO.
- The Vasculature: In the context of UPJO, "crossing vessels" are those renal arteries or veins found in the region of the ureteric transition point.
- The Ureter: The normal ureter inserts at the inferior aspect of the renal pelvis at an oblique angle and with gradual taper. It has been noted that in the setting of UPJO, the ureter tends to have a more cephalad or acute insertion.
- Therapy: Characteristic symptoms with morphologic evidence of UPJO may indicate a need for therapy.
- Such symptoms include intermittent pain after drinking large volumes of fluid or fluids with a diuretic effect.
- Asymptomatic UPJO may be treated if there is evidence of asymmetric function or deterioration in renal function or hydronephrosis.
 Imaging Findings for Ureteropelvic junction obstruction
- Hydronephrosis to the level of the ureteropelvic junction.
Patient #1: CT images demonstrate left UPJ obstruction
 See Also
 External Links
 References for Ureteropelvic junction obstruction
- Leo P. Lawler, Thomas W. Jarret, Frank M. Corl, and Elliot K. Fishman. Adult Ureteropelvic Junction Obstruction: Insights with Three-dimensional Multi–Detector Row CT. RadioGraphics 2005 25: 121-134.