Insufficient submucosal length of the ureter relative to its diameter causes inadequacy of the valvular mechanism. This is precipitated by a congenital defect/lack of longitudinal muscle of the intravesical ureter resulting in an ureterovesicular junction (UVJ) anomaly.
In this category the valvular mechanism is intact and healthy to start with but becomes overwhelmed by raised vesicular pressures associated with obstruction, which distorts the ureterovesical junction. The obstructions may be anatomical or functional. Secondary VUR can be further divided into anatomical and functional groups as follows:
Anatomical: Posterior urethral valves; urethral or meatal stenosis.
These causes are treated surgically when possible.
Functional: Bladder instability, neurogenic bladder and non-neurogenic neurogenic bladder Urinary tract infections may cause reflux due to the elevated pressures associated with inflammation.
* Grade I – reflux into non-dilated ureter
* Grade II – reflux into the renal pelvis and calyces without dilatation
* Grade III – mild/moderate dilatation of the ureter, renal pelvis and calyces with minimal blunting of the fornices
* Grade IV – dilation of the renal pelvis and calyces with moderate ureteral tortuosity
* Grade V – gross dilatation of the ureter, pelvis and calyces; ureteral tortuosity; loss of papillary impressions