Hydronephrosis

Hydronephrosis is swelling of one or both kidneys caused by urine that can't drain properly. It's not a disease by itself — it's a sign of another problem, usually a blockage in the urinary tract, but sometimes a problem with urine flowing backwards from the bladder. If not relieved, the pressure can damage the kidney and affect its function.

Causes

In adults:

• Kidney or ureter stones — common, especially in hot-climate, dehydrated populations; India has a high stone burden
• Enlarged prostate (BPH) — in older men
• Pregnancy — mild hydronephrosis is common and usually resolves after delivery
• Tumours — of the bladder, prostate, cervix, or lymph nodes pressing on the ureter
• Retroperitoneal fibrosis
• Previous surgery or radiation scarring
• Neurogenic bladder

In children:

• Congenital abnormalities — pelvi-ureteric junction (PUJ) obstruction, posterior urethral valves, vesicoureteric reflux
• Many are detected before birth on antenatal ultrasound

Symptoms

Depends on how quickly it develops:

• Sudden obstruction (e.g. a stone) — severe pain in the flank or lower back, often radiating to the groin; blood in urine; nausea and vomiting
• Slow, gradual hydronephrosis — often no symptoms until late. May present as a dull ache, recurrent UTIs, or be picked up incidentally on ultrasound
• If infection develops (pyonephrosis) — high fever, severe pain, signs of sepsis. A surgical emergency.
• Hydronephrosis of both kidneys (usually from bladder outlet obstruction) — reduced urine output, swelling, signs of kidney failure

Diagnosis

• Ultrasound — first-line imaging, shows the dilated kidney clearly
• CT scan — identifies stones, tumours, and other causes precisely
• Blood tests — kidney function, electrolytes, signs of infection
• Urine tests
• Special tests — nuclear medicine scans (DTPA or MAG3) to assess kidney function and drainage; cystoscopy; urodynamics

Treatment

Treatment is directed at relieving the obstruction and protecting kidney function:

• Urgent drainage — a ureteric stent (placed through the bladder to the kidney) or a percutaneous nephrostomy (tube through the skin into the kidney). Essential for infected obstruction or rapidly worsening kidney function.
• Treating the cause — stone removal (ESWL, ureteroscopy, PCNL), prostate treatment, tumour management, surgery for congenital obstruction
• Antibiotics — if infection is present
• Pain relief — for painful obstructions
• In pregnancy — most cases resolve spontaneously; intervention only if severe

Outcomes depend on how long the obstruction has been there. A kidney obstructed for too long may lose function permanently, which is why prompt diagnosis and drainage matter. Nephrology and urology services are available through government medical college hospitals and private specialty centres in India.