The diagnosis of PUJO is often first suspected by using ultrasonography (USG). The presence of hydronephrosis on USG raises suspicion of PUJO. Hydronephrosis is the distension and dilation of the renal pelvis and calyces and is usually caused by obstruction of the free flow of urine from the kidney.
All patients with hydronephrosis, defined by a renal pelvic diameter greater than or equal to 5mm are investigated for PUJO.
All patients undergo USG for determining the anteroposterior renal pelvis diameter, thickness of the renal cortex, presence of concomitant ureteric dilatation on the same side and evaluation of the opposite kidney and the urinary bladder.
A micturating cystourethrogram (MCU) is performed as part of the initial investigations to rule out associated vesicouretric reflux.
In a number of infants with PUJO, hydronephrosis is spontaneously resolving without apparent signs of loss of renal function.
Therefore, currently close surveillance of PUJO is the norm (patients are started on prophylactic antibiotics to prevent urinary infections) and surgical intervention is indicated only in case of worsening renal pelvic dilatation, thinning of the cortex of the affected kidney and occurrence of urinary infections secondary to PUJO.