Vesi­coure­teral reflux (VUR): urine flowing back to the kidney

What is reflux?

Normally, urine flows in only one direction, from the kidney down the ureter to the bladder. The ureter passes through the bladder wall as a slanted tunnel, and as the bladder fills, this tunnel is squeezed shut and acts as a valve. When the tunnel is short or weak, urine flows backward toward the kidney. This is called vesicoureteral reflux (VUR).

Reflux itself does not cause pain. The problem is that germs that get into the bladder can reach the kidney with the urine and cause a febrile kidney infection (pyelonephritis). Repeated infections can leave scars in the kidney.

Reflux is found in about one third of children who have had a febrile urinary tract infection.

Grades

Reflux is divided into five groups by the grade seen on the VCUG:

Grade	What is seen
I	Urine goes back only into the ureter and does not reach the kidney
II	It reaches the renal pelvis, with no dilation
III	The pelvis and ureter are mildly to moderately dilated
IV	Moderate dilation, the shape of the calyces starts to change
V	Severe dilation, the ureter is tortuous, the calyces have lost their shape

The higher the grade, the lower the chance it will resolve on its own and the higher the risk of kidney scarring.

Causes

• Primary reflux. A congenitally short ureteral tunnel. This is the most common type. It tends to run in families.
• Secondary reflux. Caused by high pressure in the bladder: posterior urethral valves, neurogenic bladder, severe bladder and bowel dysfunction.

How is it found?

• Hydronephrosis is seen on ultrasound during pregnancy or after birth,
• the child has a febrile urinary tract infection,
• the child is checked because reflux runs in the family.

The main test that confirms the diagnosis is the VCUG (voiding cystourethrogram). A DMSA scan is done to see whether there is scarring in the kidney.

Treatment

The goal of treatment is not to eliminate reflux at any cost, but to prevent febrile infections and new kidney scars. That is why the plan is individual for each child.

Toilet habits and constipation

Holding urine during the day, putting off going to the toilet, and constipation make reflux worse and open the way to infection. Treating these sometimes stops the infections on its own. More details: bladder and bowel dysfunction.

Antibiotic prophylaxis

A low dose of antibiotic is given once a day, in the evening. It reduces the number of febrile infections, especially in babies and in high-grade reflux.

Monitoring

In children with mild reflux who have not had infections, monitoring without prophylaxis is also possible. In this case the parent must know to get a urine test right away if there is a fever.

Surgical treatment

Surgical treatment is discussed in these situations: febrile infections keep coming back despite prophylaxis, new kidney scarring develops, or high-grade reflux does not resolve as the child grows.

• Endoscopic injection. A special gel is injected under the opening of the ureter through a cystoscope. There is no incision, and the child often goes home the same day. Success after one injection is about 70–90%, depending on the grade of reflux.
• Ureteral reimplantation. A long tunnel is created for the ureter using an open, laparoscopic or robotic approach. Success is above 95%.