What Do VUR Grades (1–5) Mean?

The grade of VUR is determined with a VCUG (voiding cystourethrogram). Contrast material is instilled into the bladder through a thin catheter; on the images taken during filling and voiding, the extent to which the contrast rises into the ureter and kidney, and how dilated the system is, are assessed.

In grade 1, urine flows back only into the ureter, does not reach the kidney, and the ureter is not dilated. In grade 2, urine rises all the way to the kidney's collecting system (the renal pelvis and calyces); however, neither the ureter nor the kidney is dilated, and the sharp tips of the calyces are preserved.

In grade 3, the ureter and the kidney's collecting system are mildly to moderately dilated; the sharp tips of the calyces are slightly blunted. In grade 4, dilation is moderate, the ureter begins to become tortuous, the calyceal angles are lost, but the impressions of the renal papillae can still be made out. In grade 5, the ureter is markedly dilated and tortuous, the collecting system is severely dilated, and papillary impressions are no longer visible.

The most important message for families is this: grade is a risk indicator, not a treatment prescription. Two children with the same grade can be managed very differently. A 3-year-old who has never had an infection and has healthy kidneys may be followed with grade 3 reflux under observation alone, while even grade 2 reflux may call for intervention in a baby who develops a febrile infection while on antibiotic prophylaxis and is found to have scarring on DMSA.

In primary reflux, the expected direction is downward: with growth, the tunnel lengthens, and the grade falls, or the reflux disappears, on follow-up imaging. This process takes years; resolution is commonly seen within the first 2–3 years for low grades, and it is slower for high grades.