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Hydronephrosis (Swollen Kidney)
Hydronephrosis is swelling of a kidney because urine cannot drain properly and backs up. It is a sign of a blockage or backflow, not a disease on its own.
Causes & risk factors
- A kidney stone blocking urine flow
- Enlarged prostate in men
- A narrowing (stricture) in the urinary tract
- A tumour pressing on the ureter
- Backflow of urine (reflux), including in pregnancy
Common symptoms
- Back or side pain
- Abdominal pain
- Nausea and vomiting
- Painful urination
- Fever if infected
- Reduced urine output
Tests & diagnosis
- Ultrasound of the kidneys
- CT scan
- Urine test
- Creatinine
- Kidney function (RFT)
Treatment & management
- Relieving the blockage — treating the stone, prostate or stricture
- Draining the kidney (stent or nephrostomy) if urgent
- Treating any infection promptly
- Fixing the underlying cause to protect the kidney
- Monitoring kidney function afterwards
When to see a doctor urgently
- Severe pain with fever — urgent (infected, blocked kidney)
- Being unable to pass urine
- Reduced urine output with swelling
- Persistent flank pain
Not a diagnosis. MedDroid gives general educational information about hydronephrosis (swollen kidney). It cannot examine you, diagnose or prescribe — always confirm with a qualified doctor.
Frequently asked questions
Is hydronephrosis dangerous?
It can damage the kidney if the blockage is not relieved, and becomes an emergency if the trapped urine gets infected. Prompt treatment usually protects the kidney.
What causes urine to back up?
Anything blocking flow — a stone, an enlarged prostate, a narrowing or a tumour — or backflow (reflux). Finding and treating the cause resolves the swelling.
Explore more
Sources & further reading
- World Health Organization (WHO)
- MedlinePlus — U.S. National Library of Medicine
- Ministry of Health & Family Welfare, India
- Indian Council of Medical Research (ICMR)
Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.