Hydronephrose

Hydronephrose, or hydronephrosis, is the dilation of the renal pelvis and calyces caused by obstruction to urine flow or increased urine production. It can be unilateral or bilateral and may be present at birth or develop later. In adults, common causes include kidney stones, ureteropelvic junction obstruction, tumors, ureteral strictures, and functional disorders such as neurogenic bladder. In children, congenital UPJ obstruction and vesicoureteral reflux are frequent.

The dilation increases intrapelvic pressure, can compress renal tissue, and if prolonged may lead to thinning of the kidney parenchyma and reduced function.

Most hydronephrosis is asymptomatic. When present, symptoms can include flank or abdominal pain, urinary tract infection, hematuria, or an abdominal mass. In infants, irritability or poor feeding may occur.

Diagnosis usually starts with ultrasound, which shows dilation of the renal pelvis and calyces. Further evaluation with CT urography or MRI clarifies anatomy and cause. Nuclear medicine renography assesses drainage and differential renal function to guide management.

Management targets relief of obstruction and preservation of renal function. Some mild or unilateral cases with preserved function are observed. Obstructive etiologies may require endoscopic stenting or nephrostomy, surgical reconstruction, or, when function is lost, nephrectomy.

Prognosis depends on the cause and duration of obstruction and on renal reserve. Regular follow-up is advised, especially for congenital conditions or after intervention.