Eight-year-old boy with diffuse intermittent abdominal complaints in recent years, attributed to acute banal processes. No personal or family history of interest. No urinary infections or other urinary symptoms.

Coinciding with an episode of abdominal pain in the right hemiabdomen, an abdominal ultrasound was performed, which revealed mesenteric adenitis and mild dilatation of the right renal pelvis, with suspected stenosis of the UPU. Urine sediment and urine culture were normal.

The abdominal pain disappeared spontaneously, but the patient was referred to Paediatric Nephrology for follow-up.

In the control ultrasound, while asymptomatic, dilatation of the urinary tract with mild-moderate dilatation of the right renal pelvis was still visible, so an isotopic renogram was requested (suspicion of pyeloureteral junction stenosis). The renogram confirmed obstructive ectasia in the right kidney. The renal scintigraphy study showed an increase in right renal size, with evident hypocaptation along the medial border, signs of dilatation of the tract, with a renal function of 58.8% in the left kidney and 41.2% in the right kidney.

Given the dilatation of the urinary tract due to obstructive causes, the patient was referred to paediatric urology for surgery. A nephrostomy catheter was placed for a few months to recover and prevent deterioration of renal function5,6. After removal of the nephrostomy catheter, imaging, clinical and analytical controls continued to be carried out, with progressive normalisation.