Home bladder pressure measurements correlate with urodynamic storage pressures and high-grade hydronephrosis in children with spina bifida

Abstract

Patients with spina bifida are at risk for developing bladder and renal deterioration secondary to increased bladder storage pressures. To determine the association of home bladder volume and pressure measurements (home manometry) to: 1) detrusor storage pressures on urodynamics (UDS); and 2) the presence of Society of Fetal Urology (SFU) grades 3-4 hydronephrosis on renal bladder ultrasound in patients with spina bifida. Data were prospectively collected on patients with spina bifida and neurogenic bladder requiring clean intermittent catheterization. Patients used a ruler and typical catheterization equipment to measure bladder pressures and volumes at home. Home measurements were compared to UDS detrusor pressures and SFU hydronephrosis grade. Detrusor pressure <20cmH2O at 50% maximal cystometric capacity (MCC) on UDS was used as a measure of safe storage pressures on UDS; conversely, detrusor pressure >20cmH2O was used a measure to capture both unsafe storage pressures and those with potential for unsafe storage pressures. Receiver-operator characteristic curves and area under curve (AUC) were calculated to depict the association between home manometry variables with detrusor pressures on UDS and SFU grades 3-4 hydronephrosis. Included were 52 patients with a median age of 10.3 years (interquartile range 6.3-14.4 years). Three home manometry measurements (maximum bladder pressure, bladder pressure at maximum catheterized volume, and mean bladder pressure)>20cmH2O were sensitive for Pdet >20cmH2O at 50% MCC. Maximal bladder pressure >20cmH2O was the most sensitive among home manometry measures (sensitivity 100%, specificity 70%, AUC 0.92 for Pdet >20cmH2O at 50% MCC on UDS; sensitivity 100%, specificity 62%, AUC 0.89 for SFU grade 3-4 hydronephrosis). None of the patients who had maximum home bladder pressure <20cmH2O had SFU grades 3-4 hydronephrosis; conversely, individuals with maximal home bladder pressure >20cm had a wide range of hydronephrosis grades. None of the patients with maximal home bladder pressure <20cmH2O had grade 3-4 hydronephrosis. Home measurements of maximal bladder pressure, bladder pressure at maximum catheterized volume and mean bladder pressure of >20cmH2O were all sensitive for Pdet >20cmH2O at 50% MCC on UDS. Home manometry is an inexpensive and simple technique to identify patients at risk for and to monitor individuals at high risk of upper tract dilation, without incurring significant cost or morbidity.