Hydronephrosis is swelling of one or both kidneys. Kidney swelling happens when urine can't drain from a kidney and builds up in the kidney as a result. This can occur from a blockage in the tubes that drain urine from the kidneys (ureters) or from an anatomical defect that doesn't allow urine to drain properly.
Hydronephrosis can happen at any age. Hydronephrosis in children may be diagnosed during infancy or sometimes during a prenatal ultrasound before the baby is born.
Hydronephrosis doesn't always cause symptoms. When they occur, signs and symptoms of hydronephrosis might include:
- Pain in the side and back (flank pain) that may travel to the lower abdomen or groin
- Urinary problems, such as pain with urination or feeling an urgent or frequent need to urinate
- Nausea and vomiting
- Failure to thrive, in infants
Causes of Hydroenephrosis Treatment
Normally, urine goes from the kidney to the tube that drains the kidney (ureter), to the bladder and then out of the body. But, sometimes urine backs up or remains inside the kidney or in the ureter. That's when hydronephrosis can develop.
Some common causes of hydronephrosis include:
- Partial blockage in the urinary tract. Urinary tract blockages often form where the kidney meets the ureter, at a point called the ureteropelvic junction. Less commonly, blockages may occur where the ureter meets the bladder at what's called the ureterovesical junction.
- Vesicoureteral reflux. Vesicoureteral reflux happens when urine flows backward through the ureter from the bladder up into the kidney. Normally, urine flows only one way in the ureter. Urine flowing the wrong way makes it difficult for the kidney to empty properly and causes the kidney to swell.
Less-common causes of hydronephrosis include kidney stones, a tumor in the abdomen or pelvis, and problems with nerves that lead to the bladder.
What are the symptoms of hydronephrosis?
Normally, urine flows through the urinary tract with minimal pressure. Pressure can build up if there’s an obstruction in the urinary tract. After urine builds up for an extended period, your kidney can enlarge.
Your kidney may become so engorged with urine that it starts to press on nearby organs. If it’s left untreated for too long, this pressure can cause your kidneys to lose function permanently.
Mild symptoms of hydronephrosis include urinating more frequently and an increased urge to urinate. Other potentially severe symptoms you may experience are:
- pain in the abdomen or flank
- pain when urinating
- incomplete voiding, or bladder emptying
- a fever
Interrupting the flow of urine increases your chances of getting a urinary tract infection (UTI). This is why UTIs are one of the most common complications of hydronephrosis. Some signs of a UTI include:
- cloudy urine
- painful urination
- burning with urination
- a weak urine stream
- back pain
- bladder pain
- a fever