Vesicoureteral reflux (VUR) is a condition where urine flows backward from the bladder into the ureters, which are the tubes connecting to the kidneys. This reverse flow occurs due to a malfunction in the valve that should keep urine moving in one direction. The condition is most often identified in infants and young children, affecting an estimated 1-3% of this population, and is often discovered during investigations for other issues.
Causes and Symptoms of Vesicoureteral Reflux
Vesicoureteral reflux is categorized into two types: primary and secondary. Primary VUR is the most common form and is congenital, meaning children are born with it. It occurs because the tunnel where the ureter enters the bladder is too short, preventing the valve-like mechanism from closing properly.
Secondary VUR is less common and results from other urinary tract issues, such as a blockage at the bladder outlet or problems with nerves controlling bladder emptying. Conditions like dysfunctional voiding, where a child infrequently empties their bladder, can also contribute to VUR. In these cases, increased pressure within the bladder can overwhelm a functional valve.
The most common indicator of VUR is a recurrent urinary tract infection (UTI), and about 30% to 40% of infants and toddlers with a UTI are found to have VUR. Symptoms of a UTI in a child can include a persistent fever without another clear cause, pain or burning during urination, and cloudy or strong-smelling urine. Other signs that may point to VUR include new wetting accidents in a potty-trained child, abdominal pain, or poor weight gain.
Diagnosis and Grading
When VUR is suspected after a child experiences a UTI, doctors recommend imaging tests to confirm the diagnosis. The primary diagnostic tool is a voiding cystourethrogram (VCUG). This procedure involves placing a catheter into the bladder to fill it with a contrast liquid visible on X-rays. As the bladder is filled and emptied, the images show if the liquid flows backward into the ureters and kidneys.
A kidney and bladder ultrasound is another diagnostic tool. This non-invasive test uses sound waves to create images of the urinary tract, allowing doctors to check kidney size and shape. It can reveal swelling (hydronephrosis) or scarring from past infections and can sometimes detect issues before birth.
Once VUR is confirmed, it is assigned a grade from 1 to 5 to describe its severity. Grade 1 is the mildest, where urine refluxes only partway up the ureter. In Grade 2, urine reaches the kidney but does not cause swelling. Grade 3 shows mild swelling of the ureter and the part of the kidney that collects urine. Grade 4 involves moderate swelling of the ureter and kidney, and the ureter appears crooked. Grade 5 is the most severe, with significant swelling and twisting of the ureter and substantial enlargement of the kidney’s collecting system.
Medical Management and Treatment
The treatment strategy for vesicoureteral reflux depends on the grade of the condition and the child’s overall health. For lower-grade VUR (Grades 1-2 and sometimes 3), the approach is often active surveillance, as mild reflux can resolve on its own as a child grows. This involves regular check-ups and urine tests to monitor for infections.
To prevent UTIs and potential kidney damage during monitoring, doctors may prescribe a low-dose daily antibiotic. This prophylactic use is intended to keep the urine sterile. This reduces the risk that refluxing urine will carry bacteria to the kidneys and cause an infection (pyelonephritis).
For higher-grade VUR, persistent cases, or when a child has febrile UTIs despite antibiotics, surgery may be recommended. One minimally invasive option is an endoscopic procedure where a bulking agent is injected near the ureteral opening to help it close. A more definitive surgery is ureteral reimplantation, where a surgeon creates a new, longer tunnel for the ureter within the bladder wall to correct the valve.
Potential Complications
The primary concern with vesicoureteral reflux is the potential for long-term kidney damage. When urine with bacteria flows backward from the bladder, it can lead to kidney infections (pyelonephritis). These infections are more serious than bladder infections and may cause high fever and back pain.
Repeated kidney infections can cause permanent scarring of the kidney tissue. This scarring can impair the kidney’s ability to filter waste and regulate blood pressure. Significant renal scarring can contribute to high blood pressure (hypertension), even in childhood.
In severe cases, extensive kidney scarring from VUR can lead to a decline in overall kidney function. This may progress to chronic kidney disease, which requires more intensive medical management.