Vesicoureteral Reflux (VUR)
Summary
Vesicoureteral Reflux (VUR) is the retrograde flow of urine from the bladder up the ureters into the kidneys. It affects ~1% of children and is found in 30-50% of children presenting with febrile UTIs. The primary defect involves the Vesicoureteral Junction (VUJ) which normally acts as a one-way flutter valve. Failure of this valve exposes the kidney to high bladder pressures and infected urine, leading to Pyelonephritis and permanent Renal Scarring (Reflux Nephropathy). The ultimate sequelae are Hypertension and Chronic Kidney Disease (CKD). Spontaneous resolution is common in low grades. [1,2]
Key Facts
- Grading (International Reflux Study):
- Grade I: Reflux into ureter only (no dilation).
- Grade II: Into kidney but no dilation.
- Grade III: Mild dilation of ureter/pelvis.
- Grade IV: Moderate dilation + blunting of calyces.
- Grade V: Gross dilation + tortuosity (Megaureter look).
- Primary vs Secondary:
- Primary: Congenital shortness of the intravesical ureter tunnel.
- Secondary: Obstruction (PUV), Neurogenic Bladder (Spina Bifida), or dysfunctional voiding.
- Water Hammer Effect: In severe reflux, the kidney is hammered by high pressure urine with every void, causing mechanical damage even without infection.
Clinical Pearls
The Boy Rule: VUR is usually more common in girls (primary). If you find severe hydronephrosis/reflux in a newborn boy, you MUST rule out Posterior Urethral Valves (PUV). This is a medical emergency requiring catheterisation.
Reflux Nephropathy: The combination of VUR + UTI is what causes scars. Sterile reflux rarely causes scars (unless excessively high pressure). Hence, the goal of treatment is keeping the urine sterile.
Sibling Risk: Siblings of a child with VUR have a 30% risk of having it too. Screening ultrasound is often recommended.
Incidence
- 1% of the healthy paediatric population.
- 30-50% of children with symptomatic UTI.
- Race: More common in Caucasians than African-Americans.
The Valve Mechanism
- The ureter normally enters the bladder wall at an angle, creating a submucosal tunnel. As the bladder fills/contracts, the muscle compresses this tunnel, closing it.
- In VUR: The tunnel is too short or enters perpendicularly, so compression fails.
- Resolution: As the child grows, the tunnel elongates, leading to spontaneous resolution (80% of Grade I/II resolve by age 5).
Symptoms
- Blood Pressure: Mandatory in all renal patients.
- Abdomen: Palpable bladder (PUV/Retention)? Enlarged kidneys?
- Spine: Check for sacral dimple/tuft (Spina Bifida Occulta/Neurogenic bladder).
Imaging Flowchart
- Ultrasound (KUB): First line. Shows hydronephrosis (dilation) but cannot diagnose reflux directly. A normal US does not rule out VUR.
- MCUG (Micturating Cystourethrogram): Gold Standard. Contrast injected via catheter. Fluoroscopy taken during voiding. Shows grade of reflux and anatomy (urethra).
- Indication: Atypical/Recurrent UTIs under 6 months, or family history.
- DMSA Scan: Nuclear medicine (Technetium). Binds to proximal tubules.
- Purpose: Detects cortical scars (photopenic defects) and differential function (e.g., Left 20% / Right 80%). Done 4-6 months after acute infection.
- MAG3 Scan: Distinguishes obstruction from non-obstructive dilation.
Management Algorithm
DIAGNOSED VUR
↓
ANTIBIOTIC PROPHYLAXIS
(Trimethoprim / Nitrofurantoin)
+ BOWEL MANAGEMENT
↓
┌───────────┴───────────┐
NO UTIs BREAKTHROUGH UTIs
(Surveillance) or NEW SCARS
↓ ↓
Annual US / DMSA SURGERY
Wait for growth │
(Spontaneous resolution) │
┌─────────┴─────────┐
DEFLUX REIMPLANT
(Injection) (Open/Robotic)
1. Conservative (Medical)
- Goal: Prevent infection while waiting for outgrowth.
- Prophylaxis: Low dose Trimethoprim or Nitrofurantoin at night.
- Bowel/Bladder: Treat constipation aggressively (rectum compresses bladder causing dysfunction). Double voiding.
- Duration: Usually until toilet trained (age 4-5) or resolution.
2. Surgical
- Indications: Breakthrough febrile UTIs despite antibiotics, New scarring on DMSA, Grade IV-V (unlikely to resolve), Parental preference (antibiotic fatigue).
- Endoscopic Injection (STING): Injecting a bulking agent (Deflux - Dextranomer/Hyaluronic acid) beneath the ureteric orifice to lift it and create a valve effect.
- Success: 70-80%. Minimally invasive. Day case.
- Ureteric Reimplantation (Cohen/Lich-Gregoir): Operative replumbing of ureters to create a longer tunnel.
- Success: 98%.
- Drawback: Invasive, haematuria, spasms.
- Reflux Nephropathy: Focal scarring -> focal segmental glomerulosclerosis (FSGS).
- Hypertension: Renin-mediated.
- CKD: Can progress to End Stage Renal Failure requiring transplant.
- Pregnancy: Women with reflux nephropathy have higher risk of pre-eclampsia.
- Grade I-II: >80% spontaneous resolution.
- Grade III: 50% resolution.
- Grade IV-V: Rarely resolve.
- Hypertension: Requires lifelong monitoring.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| NG111 | NICE (UTI in Children) | Restricts MCUG to infants less than 6m with atypical/recurrent UTI. Focus on acute treatment. Prophylaxis controversial (RIVUR vs NICE). |
| EAU/ESPU | European Urology | Prophylaxis recommended for high grades or uncircumcised boys. |
Landmark Trials
1. RIVUR Trial (2014)
- Question: Does antibiotic prophylaxis help in VUR?
- Result: Prophylaxis reduced risk of recurrent UTI by 50%.
- Impact: Confirmed benefit of antibiotics (Trimethoprim-Sulfamethoxazole) in preventing symptomatic recurrence, though impact on scarring was less clear.
What is Reflux?
Normally, valves stop urine flowing backward from the bladder to the kidneys. In your child, these valves are leaky. When they squeeze to pee, some urine shoots back up to the kidney.
Is it dangerous?
If the urine is clean, it's usually fine. If the urine is infected (has bugs), the bacteria get a free ride straight to the delicate kidney tissue, causing a deep infection. This can leave permanent scars on the kidney.
Will they grow out of it?
Most likely, yes. As the bladder grows large, the valves tighten up naturally. We give mild antibiotics at bedtime to keep the urine clean while we wait for nature to do its work.
When do we operate?
If they keep getting kidney infections despite the medicine, or if we see new scars forming on the scan, we might inject a special gel (Deflux) to fix the valve mechanically.
Primary Sources
- NICE Guideline NG111. Urinary tract infection in under 16s: diagnosis and management. 2018.
- The RIVUR Trial Investigators. Antimicrobial Prophylaxis for Children with Vesicoureteral Reflux. N Engl J Med. 2014;370:2367-2376. PMID: 24795142.
- Tully K, et al. Vesicoureteral Reflux: A Review. JAMA Pediatr. 2015.
Common Exam Questions
- Paediatrics: "Child less than 6 months with recurrent UTI. Investigation?"
- Answer: US KUB + MCUG + DMSA (later).
- Urology: "Material used for STING procedure?"
- Answer: Deflux (Dextranomer / Hyaluronic Acid).
- Renal: "Cause of HTN in young adult with small scarred kidney?"
- Answer: Reflux Nephropathy.
- Embryology: "Origin of ureteric bud?"
- Answer: Wolffian (Mesonephric) Duct.
Viva Points
- Circumcision: Statistically significantly reduces UTI risk in boys with VUR by removing the reservoir of prepucial bacteria.
- Dysfunctional Voiding: Holding on (constipation/holding urine) creates high pressures that overcome the valve. Always treat bowels!
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.