Urinary tract infections commonly occur in people with vesicoureteral reflux. A urinary tract infection (UTI) doesn't always cause noticeable signs and symptoms, though most people have some.

These signs and symptoms can include:

• A strong, persistent urge to urinate
• A burning sensation when urinating
• Passing frequent, small amounts of urine
• Blood in the urine (hematuria) or cloudy, strong-smelling urine
• Fever
• Pain in your side (flank) or abdomen
• Hesitancy to urinate or holding urine to avoid the burning sensation

A UTI may be difficult to diagnose in children, who may have only nonspecific signs and symptoms. Signs and symptoms in infants with a UTI may also include:

• An unexplained fever
• Diarrhea
• Lack of appetite
• Irritability

As your child gets older, untreated vesicoureteral reflux can lead to:

• Bed-wetting
• Constipation or loss of control over bowel movements
• High blood pressure
• Protein in urine
• Kidney failure

Another indication of vesicoureteral reflux, which may be detected before birth by sonogram, is swelling of the kidneys or the urine-collecting structures of one or both kidneys (hydronephrosis) in the fetus, caused by the backup of urine into the kidneys.

Your urinary system includes your kidneys, ureters, bladder and urethra. All play a role in removing waste products from your body.

The kidneys, a pair of bean-shaped organs at the back of your upper abdomen, filter waste, water and electrolytes — minerals, such as sodium, calcium and potassium, that help maintain the balance of fluids in your body — from your blood.

Tubes called ureters carry urine from your kidneys down to your bladder, where it is stored until it exits the body through another tube (the urethra) during urination.

Vesicoureteral reflux can develop in two forms, primary and secondary:

• Primary vesicoureteral reflux. The cause of this more common form is a defect that's present before birth (congenital). The defect is in the functional valve between the bladder and a ureter that normally closes to prevent urine from flowing backward.

As your child grows, the ureters lengthen and straighten, which may improve valve function and eventually resolve the reflux. This type of vesicoureteral reflux tends to run in families, which indicates that it may be genetic, but the exact cause of the defect is unknown.

• Secondary vesicoureteral reflux. The cause of this form of reflux is most often from failure of the bladder to empty properly, either due to a blockage or failure of the bladder muscle or damage to the nerves that control normal bladder emptying.

Risk factors for vesicoureteral reflux include:

• Bladder and bowel dysfunction (BBD). Children with BBD hold their urine and stool and experience recurrent urinary tract infections, which can contribute to vesicoureteral reflux.
• Race. White children appear to have a higher risk of vesicoureteral reflux.
• Sex. Generally, girls have about double the risk of having this condition as boys do. The exception is for vesicoureteral reflux that's present at birth, which is more common in boys.
• Age. Infants and children up to age 2 are more likely to have vesicoureteral reflux than older children are.
• Family history. Primary vesicoureteral reflux tends to run in families. Children whose parents had the condition are at higher risk of developing it.

Siblings of children who have the condition also are at higher risk, so your doctor may recommend screening for siblings of a child with primary vesicoureteral reflux.

Kidney damage is the primary concern with vesicoureteral reflux. The more severe the reflux, the more serious the complications are likely to be.

Complications may include:

• Kidney (renal) scarring. Untreated UTIs can lead to scarring, also known as reflux nephropathy, which is permanent damage to kidney tissue. Extensive scarring may lead to high blood pressure and kidney failure.
• High blood pressure (hypertension). Because the kidneys remove waste from the bloodstream, damage to your kidneys and the resultant buildup of wastes can raise your blood pressure.
• Kidney failure. Scarring can cause a loss of function in the filtering part of the kidney. This may lead to kidney failure, which can occur quickly (acute kidney failure) or may develop over time (chronic kidney disease).