**Question:** Reflux into grossly dilated ureter belongs to which grade of Vericoureteric Reflux?

**Core Concept:** Vericoureteric reflux (VUR) is a condition where urine flows back (refluxes) from the urinary bladder into the ureter and eventually into the kidney. This process is usually caused by a defect in the ureterovesical junction (UVJ).

**Why the Correct Answer is Right:** Grade 5 VUR refers to reflux into a grossly dilated ureter, meaning the ureter is significantly enlarged and impaired in its function due to the reflux. This grade is associated with significant risk for renal parenchymal damage, as the dilated ureter impairs urine flow and increases the risk of pyelonephritis and renal scarring.

**Why Each Wrong Option is Incorrect:**

A. Grade 4 VUR: Reflux into a non-dilated ureter, which does not pose the same level of risk for renal parenchymal damage.

B. Grade 3 VUR: Reflux into a non-dilated ureter, which is less severe than Grade 5 VUR and does not involve a grossly dilated ureter.

C. Grade 1 VUR: Reflux into a normal-sized ureter without significant renal parenchymal damage risk.

D. Grade 2 VUR: Reflux into a mildly dilated ureter, which is less severe than Grade 5 VUR and does not involve a grossly dilated ureter.

**Correct Answer:** **Grade 5** VUR, as it involves reflux into a grossly dilated ureter, posing a significant risk for renal parenchymal damage.