Summary

A congenital type of ureterovesical junction obstruction may be present in the fetus or at any stage during childhood, more commonly associated with urinary tract infections and other secondary causes. We present the case of a 6-year-old boy who suffered from colic and side pain, which was worsening monthly. He suffered from a giant hydroureteronephrosis resulting from idiopathic ureterovesical junction obstruction, with no clinical or laboratory signs of urinary tract infection or other secondary causes of obstruction. Indications for surgery were a decrease in kidney function (<40%) at scintigraphy, severe hydronephrosis (>30 mm), and the coexistence of symptoms (colic pain). After surgery, kidney function returned to almost completely normal. Unexpectedly an obstruction may become symptomatic late in infancy, especially in patients with normal prenatal ultrasound screening and postnatal life, as was the case for our patient in whom the only clinical sign was pain at flank.