Bladder Volume Assessment in Pediatric Patients With Neurogenic Bladder: Is Ultrasound an Accurate Method?

Abstract

Objective: To define the accuracy of ultrasound to determine bladder volume in pediatric patients with neurogenic bladder (NB).

Methods: Retrospective analysis of children with NB in treatment with urethral clean intermittent catheterization.

Exclusion criteria: bladder surgeries, and catheterization through a channel different than urethra. Bladder volume was measured with ultrasound using the formula: anteroposterior bladder diameter by side to side diameter by distance from dome to outlet tract by 0.523 (cm³). In the same act, the patient was performed urethral catheterization and the drained volume was measured in millimeters. Finally, postvoid residual volume (PVR) was assessed with ultrasound.

Results: We performed 318 measurements in 299 patients, mean age was 9.95 years (standard deviation: 4.6), 59% were female. Most frequent etiologies of NB were myelomeningocele and lipomyelomeningocele. Mean ultrasound-determined bladder volume was 213.9cm3 (range: 20-899 cm³) and mean bladder volume drain through catheterization was 336.4 mL (range: 30-1480 mL; P : .0001). In 67.3% of the patients (n: 214) PVR was not significant, and their mean ultrasound volume was 212.7 mL and the volume evacuated by catheterization was 339.9 mL (P : .0001). In all age groups ultrasound-determined bladder volume was statistically lower than catheterized bladder volume (P : .0001). The mean percentage error of the ultrasound-determined bladder volume was 15.58% ± 44.09. Linear regression analysis and Bland-Altman plot showed low agreement between both measurement techniques.

Conclusion: In children with NB, ultrasound-determined bladder volume was statistically lower than catheterized bladder volume measured at the same moment, and this relation persisted regardless of sex, age, and the presence of PVR.