What is the management approach for a patient with a duplex urological system?

Duplex Urological System: Etiology and Management

Etiology

Duplex collecting systems represent a common congenital anomaly of the urinary tract, affecting 0.7-4% of the population with higher incidence in females, resulting from incomplete fusion of ureteric buds during embryonic development. 1

• The condition can manifest as either partial or complete duplication of the collecting system 1
• Genetic factors play a role, though specific monogenic causes have been identified in related urological anomalies 2
• The Weigert-Meyer rule typically applies: the upper pole ureter inserts ectopically and medially (prone to obstruction/ureterocele), while the lower pole ureter inserts laterally and superiorly (prone to vesicoureteral reflux) 3
• Rare exceptions to this rule exist, such as lower pole obstruction from ectopic ureters 3

Clinical Presentations

Symptomatic duplex systems commonly present with recurrent febrile urinary tract infections, hydroureteronephrosis, vesicoureteral reflux, ureterocele, and urinary incontinence in females due to ectopic ureteric insertion. 4, 5

• Lower pole pelviureteric junction (PUJ) obstruction can occur 4
• Adult presentations are less common but documented, including cases diagnosed as late as the fifth decade 5, 1
• Ureteroceles may remain asymptomatic, particularly in adults 1

Diagnostic Evaluation

Renal and bladder ultrasound serves as the first-line postnatal evaluation tool, with voiding cystourethrography (VCUG) recommended for bilateral high-grade hydronephrosis, duplex kidneys with lower pole hydronephrosis and breakthrough febrile UTIs, or abnormal bladders with febrile UTI history. 2

• DMSA scanning provides optimal visualization of cortical tissue and differential kidney function 2
• Retrograde pyelography can confirm duplicated systems and identify ectopic ureteral insertions 3
• Assess for concurrent bladder and bowel dysfunction (BBD), as its presence with VUR doubles the risk of recurrent febrile UTI 2

Management Algorithm

Initial Conservative Approach

For asymptomatic ureteroceles without infection or obstruction, observation with periodic ultrasound monitoring is appropriate, avoiding unnecessary intervention. 6

• Monitor for development of upper tract changes, UTIs, or incontinence 6
• Continuous antibiotic prophylaxis (CAP) may be considered for high-grade VUR (grades III-V) to prevent first UTI, though this increases antibiotic resistance 2
• BBD rehabilitation should precede VUR treatment when both conditions coexist 2

Surgical Decision-Making: Bottom-Up vs Top-Down

Bladder reconstructive surgery (BRS) as the initial approach significantly reduces the need for subsequent procedures compared to heminephroureterectomy (21% vs 5% requiring additional surgery, p=0.048), particularly when both reflux and ureterocele are present. 4

Bottom-Up Approach (Preferred Initial Strategy)

• Endoscopic ureterocele incision or bladder reconstructive surgery addresses both ureterocele and reflux simultaneously 4
• Indicated for symptomatic patients with dilating VUR or ureterocele 4
• Common-sheath ureteral reimplantation can address both ureters when necessary 5
• No reported cases of urinary retention or need for intermittent catheterization post-procedure 4

Top-Down Approach (Reserved for Specific Indications)

• Heminephroureterectomy with ureterectomy is indicated when the affected moiety is non-functional or severely dysplastic 3
• Consider for severe upper pole obstruction with irreversible damage 3
• Higher rate of subsequent bladder-level surgery required (21% need additional BRS) 4
• When both reflux and ureterocele present, initial heminephroureterectomy significantly increases need for further surgery (p=0.01) 4

Alternative Approaches

• Upper pole ureteral ligation and ureteroureterostomy represent emerging "less is more" strategies that may avoid bladder reconstruction in select cases 6
• Ureterostomy provides temporary drainage in acute urosepsis scenarios, followed by definitive reconstruction once stabilized 3

Acute Management of Complications

For urosepsis with severe hydroureteronephrosis, immediate urinary diversion via ureterostomy or percutaneous nephrostomy takes priority, with definitive reconstruction deferred until infection resolves. 3

• Broad-spectrum antibiotics targeting common uropathogens (Klebsiella, E. coli) 3
• Imaging to assess functionality of affected moiety guides subsequent surgical planning 3

Key Clinical Pitfalls

• Avoid routine bladder reconstruction in all duplex system patients—recent evidence suggests a significant portion do not require ureteral reimplantation or bladder neck reconstruction 6
• Do not perform endoscopic incision for asymptomatic ureteroceles 4
• Recognize that ureteroceles can be diagnosed in adults despite being considered congenital, requiring high index of suspicion in patients with recurrent UTIs 1
• The presence of duplex systems in males, though less common, still warrants thorough evaluation for recurrent UTI and ureterocele 1

Monitoring and Follow-Up

Regular surveillance includes clinical assessment, renal ultrasound for upper tract changes, monitoring of growth parameters, blood pressure, and serum creatinine to evaluate spontaneous VUR resolution and preserve renal function. 2

• Height, weight, and blood pressure monitoring at each visit 2
• Serum creatinine and GFR assessment for renal status 2
• Evaluation for breakthrough febrile UTIs 2