Physiology and evaluation of ureteropelvic junction obstruction.

Ureteropelvic junction (UPJ) obstruction is not a single anatomic entity but rather a set of processes with multiple causes. In the obstructed system, histologic changes are apparent that have implications for healing. The role of crossing vessels In UPJ obstruction and its treatment is of growing interest. Various methods are available to assess the functional characteristics of the UPJ, of which the diuretic renogram, Whitaker perfusion test, and Doppler ultrasound resistive index may be the most useful. The treatment must be individualized according to the patient's symptoms, the status of renal function, and the potential complications of intervention.