In older children and adults, undiagnosed congenital or acquired UPJ obstructions may cause intermittent, severe flank pain following increased fluid or diuretic intake. In addition, patients may experience hematuria after mild trauma, the theory being that distention of the renal pelvis causes mucosal vessels to become more friable. The diagnosis of UPJ obstruction in this population is often first suggested on contrast-enhanced CT or ultrasound. In adults and children older than 3 months of age, diuretic renography using 99mTc-MAG3 nuclear tracer should be performed once negative urine cultures have been obtained because it permits precise measurement of renal drainage. If a crossing vessel is suspected, duplex ultrasonography, CT angiography, or magnetic resonance angiography may help guide further management.

TREATMENT

Surgical intervention for UPJ obstruction is indicated for increased hydronephrosis on ultrasound (initially performed every 1 to 3 months), symptoms, stones, infection, deterioration of renal function, or hypertension. Techniques for intervention are primarily minimally invasive, and common ones are described in detail in Plate 10-16x. A subset of neonates with suspected UPJ obstruction have spontaneous resolution, and efforts to prospectively identify these patients are ongoing.