Can Vesicoureteral Reflux Present as Bilateral Hydronephrosis with Abrupt Narrowing at the VUJ on CT Urography?
No, vesicoureteral reflux (VUR) does not typically present with abrupt narrowing at the vesicoureteral junction (VUJ) on CT urography—this imaging finding suggests obstruction rather than reflux. VUR is a functional disorder where urine flows retrograde from the bladder into the ureters/kidneys, and it does not cause anatomic narrowing at the VUJ 1.
Key Imaging Distinctions
VUR Imaging Characteristics
- VUR is diagnosed by voiding cystourethrography (VCUG), not CT urography, as VCUG demonstrates retrograde flow of contrast from bladder to ureter during the voiding phase 1.
- On imaging, VUR causes dilation without obstruction—the ureter and collecting system dilate due to refluxed urine, but there is no anatomic narrowing or stenosis 1.
- When VUR is severe (grades IV-V), bilateral hydronephrosis can occur, but the VUJ appears patulous and incompetent, not narrowed 1.
Abrupt VUJ Narrowing Suggests Alternative Diagnoses
- Abrupt narrowing at the VUJ on CT urography indicates obstructive pathology, not reflux 1.
- Differential diagnoses for bilateral VUJ narrowing include:
- Bladder outlet obstruction causing secondary bilateral ureteral obstruction (prostatic hyperplasia, urethral stricture, posterior urethral valves in males) 1, 2
- Pelvic malignancy encasing or compressing both distal ureters 1, 2
- Retroperitoneal fibrosis causing bilateral ureteral encasement 1, 2
- Bilateral ureteral strictures from prior instrumentation, radiation, or ischemia 1
- Neurogenic bladder with high-pressure voiding causing functional obstruction 1, 2
Critical Clinical Pitfall
The presence of contrast in a dilated collecting system on CT does not prove the kidney is functioning—it may represent refluxed contrast from the bladder rather than renal excretion 3. This phenomenon can mimic functioning kidneys on CT urography when severe VUR is present, but the key distinguishing feature is that VUR shows no anatomic narrowing at the VUJ 3.
Appropriate Diagnostic Workup for Your Imaging Finding
When CT urography demonstrates bilateral hydronephrosis with abrupt VUJ narrowing:
- Immediate evaluation is mandatory because bilateral obstruction eliminates contralateral kidney compensation and can cause irreversible nephron loss even with normal initial creatinine 4, 5, 2.
- VCUG should be performed to definitively exclude or confirm VUR, particularly in male patients where posterior urethral valves must be ruled out 1, 2.
- MAG3 renal scan with diuretic is the gold standard for confirming true obstructive uropathy versus non-obstructive dilation 4, 5, 2.
- Cystoscopy with retrograde pyelography may be needed to define the exact level and nature of bilateral ureteral obstruction 1.
Why This Distinction Matters Clinically
- VUR management focuses on preventing recurrent UTIs and renal scarring through antibiotic prophylaxis or surgical correction 1.
- Bilateral obstructive uropathy requires urgent decompression (bilateral ureteral stents or percutaneous nephrostomy) to prevent permanent renal damage 2.
- Misdiagnosing obstruction as reflux delays life-saving intervention, while misdiagnosing reflux as obstruction leads to unnecessary invasive procedures 4, 2.