What are the congenital ureteral anomalies and the recommended diagnostic work‑up and management strategies for patients of any age?

Congenital Ureteral Anomalies: Diagnosis and Management

Overview of Ureteral Anomalies

Congenital ureteral anomalies encompass a spectrum of disorders including ureteral duplication, megaureter, ectopic ureter, ureterocele, ureterovesical junction obstruction, and congenital ureteric stenosis, which require risk-stratified imaging and individualized surgical intervention based on severity and associated complications. 1

The most common ureteral anomalies detected include: 1, 2, 3

• Ureteral duplication/duplex collecting system - occurs in <1% of the general population but up to 8% in children with urinary tract infections 4
• Megaureter - dilation of the ureter with or without obstruction 1, 4
• Ectopic ureter - ureter opening outside the normal trigone location 4, 3
• Ureterocele - cystic dilation of the distal ureter 1, 3
• Ureterovesical junction obstruction 1
• Congenital ureteric stenosis - rare but serious anomaly with obstruction at one or more ureteral levels 5

Clinical Presentation

Pediatric Presentation

• Antenatal detection via prenatal ultrasound showing urinary tract dilation (UTD), which occurs in approximately 1% of pregnancies 1
• Urinary tract infections, particularly febrile UTIs in infants and young children 1, 6
• Continuous urinary incontinence in girls with ectopic ureter opening in the vagina, septum, or urethra below the sphincter mechanism 4
• Epididymitis symptoms in boys when ectopic ureter opens into the genital tract 4
• Obstructive symptoms including hydronephrosis and potential uremia 5

Adult Presentation

• Bladder outlet obstruction symptoms in rare cases of ureteral duplication presenting in adulthood 7
• Recurrent UTIs 6
• Incidental findings on imaging for other indications 3

Diagnostic Work-Up

Initial Imaging Strategy

For antenatal UTD detection: 1

• Prenatal ultrasound at 18-22 weeks gestational age has 91% sensitivity for detecting UTD 1
• Anteroposterior renal pelvis diameter (APD) measurement: normal is <4 mm before 28 weeks and <7 mm after 28 weeks gestation 1
• Postnatal renal and bladder ultrasonography (RBUS) timing depends on severity of antenatal findings 1

For postnatal evaluation: 1, 6, 8

• Renal and bladder ultrasound is the first-line imaging modality due to low cost, wide availability, and absence of ionizing radiation 3
• Look for: hydronephrosis, hydroureter, duplex collecting systems, ureterocele, bladder wall thickening, and renal parenchymal abnormalities 1

Advanced Imaging

Voiding cystourethrography (VCUG): 6, 9, 8

• Indicated for: bilateral high-grade hydronephrosis, duplex kidneys with hydronephrosis, ureterocele, abnormal bladder appearance, or history of febrile UTIs 8
• Not routinely indicated for isolated mild renal pelvis dilatation without these features 8
• Useful for detecting vesicoureteral reflux and posterior urethral valves in male infants 6, 9

Renal scintigraphy (MAG3 scan): 6, 8

• Consider when: hydronephrosis persists or worsens on follow-up ultrasound, renal parenchymal thinning develops, or symptoms of obstruction occur 8
• Evaluates differential renal function and drainage 6

CT urography or MR urography: 3

• Reserved for complex cases requiring detailed anatomic delineation of the collecting system, vascular anatomy, and adjacent structures 3
• CT urography may be considered when malignancy is suspected 9

Risk Stratification by Severity

Mild UTD (APD <10 mm): 1, 8

• 64-75% spontaneous resolution rate 1
• Low risk of significant underlying pathology 8
• High likelihood of spontaneous resolution 8

Moderate to Severe UTD (APD ≥15 mm): 1

• Greater risk of ureteropelvic junction obstruction and posterior urethral valves 1
• Higher likelihood of requiring surgical intervention 1
• Worsening between second and third trimesters increases surgical risk 1

Management Strategies

Conservative Management

For mild, isolated renal pelvis dilatation: 8

• No immediate intervention required for APD <10 mm 8
• Ultrasound follow-up in 1-6 months initially 8
• Continue monitoring every 6-12 months if dilatation persists but remains stable 8
• Long-term surveillance: kidney ultrasound at least once every 2 years to monitor for "flow uropathy" 8

Antibiotic prophylaxis considerations: 1, 6

• Recommended for patients at increased risk of UTI based on severity of UTD and presence of vesicoureteral reflux 1, 6
• Trimethoprim-sulfamethoxazole is the most commonly used agent 1
• Alternative agents include nitrofurantoin, cefadroxil, or amoxicillin-clavulanate 1

Surgical Intervention

Indications for urology referral: 8, 5

• Evidence of obstruction on functional imaging 8
• Decreasing differential renal function 8
• Development of obstructive symptoms 8
• Symptomatic presentation with uremia (serum creatinine >1 mg/dL) 5
• Recurrent febrile UTIs despite prophylaxis 6

Surgical options depend on specific anomaly: 4, 5, 3

• Ureteral duplication: may require heminephrectomy, ureteroureterostomy, or ureteral reimplantation 4
• Congenital ureteric stenosis: ureteroureteral anastomosis, ureteric reimplantation, or ureteral substitution 5
• Megaureter: ureteral tapering and reimplantation 4
• Ureterocele: endoscopic incision or open surgical excision with ureteral reimplantation 3
• Ectopic ureter: ureteral reimplantation or upper pole nephrectomy in duplex systems 4, 3

Special Considerations

Associated anomalies are common: 5

• 76% (13 of 17) of children with congenital ureteric stenosis had one or more associated anomalies 5
• Most significant: contralateral multicystic dysplastic kidney 5
• Others include: ureteropelvic junction obstruction, megacalyx, vesicoureteral reflux, urogenital sinus abnormalities, and anorectal malformations 5

Long-term outcomes: 5

• Children with solitary functioning kidney are at risk of uremia in later life 5
• Satisfactory urinary drainage can be established in most cases with appropriate surgical intervention 5
• Uremia resolves in the majority of children after successful reconstruction 5

Critical Pitfalls to Avoid

• Do not delay postnatal imaging in severe bilateral UTD in males due to risk of posterior urethral valves requiring urgent intervention 1, 9
• Do not perform VCUG routinely for isolated mild hydronephrosis without additional risk factors, as this exposes children to unnecessary radiation and catheterization 8
• Do not misdiagnose congenital ureteric stenosis as simple ureteropelvic junction obstruction or primary megaureter, as it is a more serious anomaly requiring different surgical approach 5
• Do not overlook ectopic ureter in girls with continuous urinary incontinence despite normal voiding patterns 4
• Do not assume adult presentation is benign - ureteral anomalies presenting in adulthood can cause significant diagnostic and therapeutic challenges 7