Can Urodynamics or Imaging Findings in Infants with Spina Bifida Predict Future Need for Bladder Augmentation?

By: Lauren E. Corona, MD; Ted Lee, MD, MS; Julian Wan, MD; Courtney S. Streur, MD, MS | Posted on: 01 Apr 2022

As the life expectancy of individuals with spina bifida (SB) has improved, urological complications have emerged as a major cause of morbidity and mortality.1,2 Early and lifelong urological care is necessary to optimize outcomes. Currently, it is unknown if any parameters measured during infancy are predictive of poor urological outcomes later in life.

In this context, we performed a retrospective review of patients with SB at our institution to determine if abnormal finding on index cystometrogram (CMG) and voiding cystourethrogram (VCUG) during infancy predicted the need for augmentation cystoplasty for the indication of a persistently elevated detrusor leak point pressure/end fill pressure (DLPP/EFP) ≥40 cmH2O later in life. A total of 97 patients with at least 8 continuous years of followup (mean 16.7 years) between 1984 and 2017 were included.3 Infants with SB at our institution undergo CMG, VCUG and renal ultrasound (RUS) during infancy. Newborns are started on clean intermittent catheterization (CIC) with or without antimuscarinics at birth if in retention or at the time of first CMG demonstrating elevated bladder pressures or detrusor sphincter dyssynergia. RUS and CMG are repeated every 1 to 2 years until puberty. Patients who continued to have high-risk bladders (defined as DLPP/EFP ≥40 cmH2O) on repeat studies despite maximum medical therapy with CIC and antimuscarinics underwent augmentation. Patients who underwent augmentation for other indications were not included in the augmentation group.

In all, 17/97 (17.5%) patients underwent augmentation. On index studies, 33/97 (34%) had a DLPP/EFP ≥40 cmH2O and 30/97 (31%) had VUR (50% grades 1–2, 50% grades 3–5). Of those with an abnormal index CMG, 10/33 (30%) ultimately underwent augmentation. Of those with VUR on index VCUG, 9/30 (30%) ultimately underwent augmentation. Of the 17 patients who underwent augmentation, 7/17 (41%) did not have DLPP/EFP ≥40 cmH2O on index CMG and 8/17 (47%) did not have VUR on index VCUG. Descriptive statistics revealed that patients with high-risk bladder on index CMG or VUR during infancy were more likely to undergo augmentation, which were subsequently found to be independent predictors on binomial logistic regression (p=0.02, p=0.03, respectively; tables 1 and 2). Other potential predictive factors analyzed were gender, level of lesion, hydronephrosis in infancy, initiation of CIC in infancy, and initiation of antimuscarinics in infancy. These were not associated with future augmentation.

Table 1. Patient characteristics

Variable Conservative Management Augmentation Cystoplasty p Value
Total No. pts 80 17
No. gender (%):
 Female 38 (47.5) 8 (47.1) 0.98
 Male 42 (52.5) 9 (52.9)
No. level of lesion (%):
 Thoracic 7 (8.8) 2 (11.8) 0.87
 Lumbar 42 (52.5) 10 (58.8)
 Lumbosacral 22 (27.5) 3 (17.6)
 Sacral 9 (11.2) 2 (11.8)
DLPP/EFP ≥40 cm H2O on index CMG, high-risk bladder (%) 23 (28.8) 10 (58.8) 0.02
No. hydronephrosis before 1 year (%):* 17 (21.2) 3 (17.6) 0.74
 SFU grades 1–2  10 / 17 (58.8)  2 / 3 (66.7) 0.99
 SFU grades 3–4  7 / 17 (41.2)  1 / 3 (33.3)
No. presence of VUR before 1 year (%): 21 (26.3) 9 (52.9) 0.03
 Grades 1–2  10 / 21 (47.6)  5 / 9 (55.6) 0.69
 Grades 3–5  11 / 21 (52.4)  4 / 9 (44.4)
No. CIC (%): 68 (85) 17 (100) 0.04
 Noncompliance  12 / 68 (17.6)  3 / 17 (17.6) 1.00
No. anticholinergics (%) 66 (82.5) 16 (94.1) 0.11
*Hydronephrosis SFU grades 1 or 2 versus grades 3 or 4 is not associated with augmentation cystoplasty.
Low versus high grade of vesicoureteral reflux is not associated with augmentation cystoplasty.
All patients with elevated DLPP/EFP greater than 40 cm H2O or vesicoureteral reflux during infancy started on CIC. DLPP/EFP: Detrusor leak point pressure/end fill pressure; CMG: Cystometrogram; VUR: vesicoureteral reflux; CIC: clean intermittent catheterization.

Table 2. Binomial logistic regression for predictors in infancy for future augmentation cystoplasty

Odds Ratio 95% CI p Value
High-risk bladder on index CMG 3.89 1.26–11.99 0.02
VUR 3.51 1.14–10.85 0.03

Despite the importance of preserving renal function for improved morbidity and mortality in this population, there are limited data on early predictors of poor renal and urologic outcomes in the SB population. The ongoing Centers for Disease Control and Prevention-funded UMPIRE study is prospectively working to both systematically monitor renal outcomes and develop guidelines for the urological management of infants and children with SB.4 They have shown that baseline renal imaging is normal in the majority of SB patients (56% of infants had normal RUS and 85% had no VUR).5 Our cohort similarly had low rates of hydronephrosis (79% with normal RUS) and of VUR (70% with normal VCUG) on initial imaging. Importantly, they have clearly demonstrated the poor interrater reliability of interpreting urodynamics.6 The majority of patients in our study were followed by a single urologist, minimizing this important limitation.

This study demonstrates that while initial unfavorable findings on index CMG and VCUG are associated with an increased likelihood of future augmentation, they are not entirely predictive. Of those who underwent augmentation, 12/17 had an unfavorable finding on index imaging, while 5/17 did not. Conversely, 46/58 (79%) patients with an initial unfavorable finding did not require augmentation by last followup. Clearly, some high-risk bladders stay “bad,” some improve, and some low- and intermediate-risk bladders “go bad.” The reason for this remains unclear, possibly related to progression or improvement of neurologic disease, urological insults such as urinary tract infections (UTIs), and medical and surgical management. What medical and surgical intervention initiated at what point could improve outcomes for high-risk bladders or prevent bladders from becoming high risk? Hopefully the long-term findings from the UMPIRE study will be able to address these important questions.

The value of surgery as an outcome has been heavily debated in the pediatric urology community. Surgery cannot be strictly objectified as the influences of health beliefs, family support and motivation, and surgeon attitudes all contribute to such decisions and are difficult, if not impossible, to measure. In the urological literature, the use of pyeloplasty as an outcome for ureteropelvic junction obstruction is especially controversial as there is large variation in the indication for (eg for obstruction only vs obstruction with diminished function) and timing of intervention. Acknowledging the limitation of using surgery as an outcome in this study, in the absence of a better alternate outcome, we have mitigated its impact. While bladder reconstruction rates vary across centers,7 our data represent a single institution with a standardized management protocol and largely a single surgeon experience. Additionally, we only included those patients who underwent augmentation for a specific, (relatively) objective indication of DLPP/EFP ≥40 cm H2O. Finally, while there is great merit to this academic debate, the “outcome” of greatest interest to the families we care for is whether the child will require a major, life-altering surgery due to a high-risk bladder. Other alternatives such as chronic kidney disease would be a poor substitution due to limitations in estimating renal function in children with SB.8 An increase in UTI is similarly problematic in this population with only recent standardization of its definition.6,9

Our findings suggest that a high-risk bladder on index CMG and/or VUR in infancy are predictive of future augmentation in patients with SB. More importantly, we conclude that the majority of infants with SB, even in the setting of a high-risk bladder and/or VUR in infancy, will safely avoid augmentation with conservative management, stressing the importance of close monitoring and adherence to bladder management. The decision to proceed with augmentation should be viewed in the context of additional outcomes including infection, renal disease and changes in bladder dynamics. Ongoing efforts to study these predictors with rigorously designed standardized clinical pathways should be encouraged and supported.4

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