hydronephrosis

Hydronephrosis is dilation of the renal pelvis and calyces due to urine accumulation from obstruction or impaired drainage. It can be unilateral or bilateral and may be acute or chronic; chronic obstruction can cause thinning of renal parenchyma and loss of function.

Causes include obstructive etiologies such as kidney stones, ureteral strictures, tumors, blood clots, pregnancy-related compression, and retroperitoneal fibrosis; vesicoureteral reflux and bladder dysfunction; congenital anomalies such as UPJ obstruction; and functional obstruction from neurogenic bladder.

Most cases are asymptomatic and found incidentally. Symptoms, when present, may include flank pain, urinary symptoms, fever with infection, or a palpable mass in advanced disease.

Diagnosis: ultrasound is first-line, showing dilation and possibly cortical thinning. CT urography or MRI provides anatomy; diuretic renography assesses drainage and function. Urinalysis and cultures help detect infection; renal function tests assess kidney status.

Management: treat the underlying cause and relieve obstruction. Mild cases may warrant observation; acute obstructive cases with infection require urgent drainage (catheter or percutaneous nephrostomy). Endoscopic stone or stricture treatment, ureteral stenting, or surgical procedures such as pyeloplasty may be used. Bilateral obstruction or compromised renal function requires prompt intervention.

Prognosis varies with duration and severity; early relief of obstruction helps preserve renal function.