When urine cannot drain from the kidney to the bladder due to a blockage, obstruction or backflow of urine from bladder, the kidney swells. This swelling is known as hydronephrosis. Swelling can occur in one or both kidneys, and may or may not be accompanied by symptoms including pain in the side, back, abdomen or groin, nausea and fever. Painful urination, an urgent need to go or to go more frequently, incomplete urination and incontinence are other common symptoms.

Often, hydronephrosis is caused by an underlying illness or health issue, including:

• Urinary tract infection
• Blood clot
• Kidney stone
• Birth defect
• Scar tissue (from a previous surgery)
• Pregnancy
• Enlarged prostate
• Tumor or cancer (bladder, cervical, colon or prostate)

Once the underlying cause is determined, an appropriate treatment plan can be prescribed to address the health issue.

Kidney swelling can be detected in several ways. Imaging tests such as ultrasound, x-rays, computerized tomography (CT) and magnetic resonance imaging (MRI) allow physicians to view the kidneys. A cystoscopy can provide a view inside the bladder and urethra. Blood and urine tests may also be conducted to check kidney function.

Once the underlying cause of hydronephrosis is identified, it is treated to alleviate swelling in the kidneys. Infections are treated with antibiotics. Kidney stones may pass on their own or need surgical removal.

In cases where severe blockage causes hydronephrosis, excess urine may be drained from the bladder using a catheter, or directly from the kidney using a nephrostomy (a thin tube used to drain the kidney).

Hydronephrosis should be treated as soon as possible to avoid permanent kidney damage. Severe cases of hydronephrosis can lead to kidney failure. With prompt treatment, though, most people recover fully from hydronephrosis.