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

BACKGROUND

Patients with spina bifida are at risk for developing bladder and renal deterioration secondary to increased bladder storage pressures.

OBJECTIVES

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.

METHODS

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 <20 cm H2O at 50% maximal cystometric capacity (MCC) on UDS was used as a measure of safe storage pressures on UDS; conversely, detrusor pressure >20 cm H2O 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.

RESULTS

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) > 20 cm H2O were sensitive for Pdet >20 cm H2O at 50% MCC. Maximal bladder pressure >20 cm H2O was the most sensitive among home manometry measures (sensitivity 100%, specificity 70%, AUC 0.92 for Pdet >20 cm H2O 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 <20 cm H2O had SFU grades 3-4 hydronephrosis; conversely, individuals with maximal home bladder pressure >20 cm had a wide range of hydronephrosis grades.

CONCLUSION

None of the patients with maximal home bladder pressure <20 cm H2O had grade 3-4 hydronephrosis. Home measurements of maximal bladder pressure, bladder pressure at maximum catheterized volume and mean bladder pressure of >20 cm H2O were all sensitive for Pdet >20 cm H2O 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.