What is the management approach for a patient with a duplicated collecting system, potentially with associated conditions such as vesicoureteral reflux or ureterocele, and a history of recurrent urinary tract infections?

Management of Duplicated Collecting System with Recurrent UTIs

Initial Diagnostic Workup

Obtain a voiding cystourethrography (VCUG) to evaluate for vesicoureteral reflux (VUR), as duplex kidneys with hydronephrosis have a significantly higher likelihood of VUR and warrant this investigation. 1

• Renal ultrasound serves as the primary imaging modality to identify the duplex system and assess for hydronephrosis, ureterocele, or parenchymal abnormalities 2
• VCUG is specifically recommended for duplex kidneys with hydronephrosis, ureterocele, ureteric dilatation, or history of febrile UTIs, as VUR likelihood is substantially elevated in these scenarios 1
• Contrast-enhanced voiding urosonography (ceVUS) represents an alternative to VCUG with comparable diagnostic accuracy 1
• Consider DMSA scan to assess for renal scarring and determine individual kidney function, particularly when guiding treatment decisions 1
• CT urography or MR urography should be obtained when complex anatomy requires detailed definition before surgical planning 2

Medical Management Strategy

Initiate continuous antibiotic prophylaxis (CAP) for all children under 5 years with documented VUR in the setting of a duplex system and recurrent UTIs. 1, 2

• This recommendation carries strong evidence and applies regardless of VUR grade in children aged 1-5 years 1
• For infants diagnosed within the first year of life, treat all symptomatic patients with CAP regardless of reflux grade or presence of focal uptake defects 1
• Evaluate thoroughly for lower urinary tract dysfunction (LUTD) or bladder and bowel dysfunction (BBD) in all toilet-trained children, as this doubles the risk of UTI recurrence and must be addressed before treating VUR. 1
• Management of BBD may be as impactful as antibiotic prophylaxis in preventing recurrent infections 1

Surgical Intervention Criteria

Offer surgical reimplantation or endoscopic correction to patients experiencing frequent breakthrough infections despite prophylaxis. 1, 2

Grade-Based Surgical Approach:

• For persistent high-grade reflux (grades IV-V): Offer ureteral reimplantation, as this provides superior outcomes compared to endoscopic correction for higher grades 1, 2
• For lower-grade reflux (grades I-III): Endoscopic correction with bulking agents may be attempted first, though success rates are significantly lower in duplex systems (50%) versus single systems (73%) 2
• For children >1 year with high-grade reflux and abnormal renal parenchyma: Offer surgical repair 1
• Surgical correction should be offered if parents prefer definitive therapy over conservative management 1

Ureterocele-Specific Management:

• Children with prenatally detected ureterocele face high UTI risk (31-57%) despite prophylactic antibiotics 3
• Consider early endoscopic perforation of ureterocele, as post-perforation UTI incidence drops to only 14% 3

Risk Stratification Factors

Select management based on a comprehensive assessment of multiple prognostic factors, with particular attention to gender and VUR grade. 1

Key decision-making factors include:

• Grade of reflux: Higher grades (IV-V) require more aggressive intervention 1
• Gender: Females with moderate-to-high grade VUR in duplex systems present more often with complications and should be treated differently than males 4
• Renal parenchymal abnormalities: Presence of focal uptake defects on radionuclide scan 1
• Bilateral involvement 1
• Ipsilateral renal function 1
• Patient age: Different thresholds apply for infants versus older children 1
• Clinical course and frequency of breakthrough infections 1

Critical Management Pitfalls

Low-grade VUR (grades I-II) in duplex systems has similar outcomes to single systems and can be managed conservatively, but moderate-to-high grade VUR requires different treatment. 4

• Hydronephrosis does not always indicate obstruction; it may represent reflux, distended bladder, or postobstructive dilation requiring bladder decompression and repeat imaging 2
• Absence of hydronephrosis does not exclude ureteral pathology in duplex systems 2
• Ensure adequate hydration before functional studies, as dehydration may mask obstruction 2
• Breakthrough infections are frequently non-E. coli infections (82%), which may require different antibiotic coverage 3
• In high-risk patients with existing renal impairment, a more aggressive multidisciplinary approach is mandatory. 1

Follow-Up Protocol

Perform annual renal ultrasound to monitor both kidneys for disease progression, renal growth, and complications. 2

• Annual urinalysis with culture if indicated 2
• Functional imaging (MAG3 renal scan or MR urography) should be considered if obstruction is suspected or to establish baseline differential function before intervention 2
• Monitor for spontaneous resolution in low-grade cases, though severe VUR in duplex systems shows no resolution at mean 42-month follow-up 4

Immediate Action for Febrile Breakthrough Infections

Provide immediate parenteral antibiotic treatment for any febrile breakthrough infection. 1

• This represents a strong recommendation requiring urgent intervention 1
• Consider that 57% of UTIs in this population occur as breakthrough infections despite prophylaxis 3