Hydronephrosis: Causes, Symptoms, and Treatment
Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Hydronephrosis?
A urologist, a doctor who treats the urinary tract, often treats hydronephrosis, and a nephrologist, a doctor who treats kidney disease, may be involved too. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is hydronephrosis?
Hydronephrosis is swelling of a kidney because urine backs up. It is not a disease itself. It happens because of another problem that blocks the flow of urine. It can affect one kidney or both kidneys. The blockage and swelling can happen suddenly or build up slowly.
Symptoms
Some people have no symptoms.
When symptoms do happen, they can include:
- Pain in the lower back, side (flank pain), or belly.
- Nausea and vomiting.
- Fever.
- Painful urination, or needing to urinate more often.
- Blood in the urine.
- Less urine than usual in adults.
- A urinary tract infection (UTI), an infection of the urinary system.
In children, a belly lump may be a sign. In a baby, signs are often found before birth on a pregnancy ultrasound. An older child who gets repeat urinary tract infections should also be checked for blockage.
Causes and who gets it
Hydronephrosis is usually caused by another illness or risk factor.
Causes include:
- Kidney stones.
- Scarring that blocks a ureter after past infections, surgeries, or radiation treatments.
- An enlarged uterus during pregnancy.
- Birth defects of the urinary system.
- Vesicoureteral reflux, which is urine flowing back from the bladder toward the kidney.
- An enlarged prostate that is not cancer.
- Cancers or tumors in the ureter, bladder, pelvis, or belly.
- Blood clots.
- Problems with the nerves that supply the bladder.
How doctors diagnose it
Doctors talk with you, do a physical check-up, and order blood and urine tests. The condition is found on an imaging test, which takes pictures of the kidneys and bladder. These include an ultrasound, a CT scan, an MRI, an intravenous pyelogram (IVP), or a renal nuclear scan. Some doctors also use a cystoscope, a special telescope, to look at the bladder.
Treatment
Treatment depends on the cause of the kidney swelling. Doctors try to stop the kidney from swelling further. Options include:
- A stent, a small tube placed through the bladder and ureter so urine can flow from the kidney into the bladder.
- A tube placed into the kidney through the skin so blocked urine can drain into a bag.
- Antibiotics for infections, and medicines to ease pain.
- Surgery to correct the blockage or reflux.
- Removal of any stone that is causing the blockage.
People with long-term hydronephrosis may need antibiotics to lower the risk of a UTI. The key to treatment is to get it addressed as soon as possible to avoid permanent kidney damage. When treated quickly, most people recover from hydronephrosis. Severe hydronephrosis can lead to kidney failure, which needs dialysis or a kidney transplant.
When to see a doctor
Contact your health care provider if you have ongoing flank pain or fever, or if you think you may have hydronephrosis. People who have only one kidney, a weakened immune system, or a kidney transplant need treatment right away. Without treatment, the affected kidney may be permanently damaged.
Call 911 or go to the emergency room if you have trouble breathing, chest pain, fainting, severe belly pain or pressure, vomiting that is severe or will not stop, or a sudden change in mental state, especially with a fever.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Such a doctor can review your symptoms, help arrange tests, and refer you to a urologist or kidney doctor, and follow up with you afterward.
Common questions
Is hydronephrosis a disease?
No, hydronephrosis is not a disease itself. It is kidney swelling that happens because of another problem, such as a blockage.
Can hydronephrosis damage the kidneys?
Yes, it can. If it is not treated, the affected kidney may be permanently damaged. Kidney failure is rare if the other kidney is working normally. However, kidney failure will occur if there is only one working kidney.
Can hydronephrosis happen without symptoms?
Yes, hydronephrosis often causes no symptoms. Doctors may find it on an imaging test.
Can pregnancy cause hydronephrosis?
Yes, it can. An enlarged uterus during pregnancy can block a ureter.
Sources
- MedlinePlus - Hydronephrosis of one kidney
- National Kidney Foundation - Hydronephrosis
- MedlinePlus - Bilateral hydronephrosis
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
