Differences in urodynamic variables for vesicoureteral reflux depending on the neurogenic bladder type

Objective: To compare the urodynamic study variables at the onset of vesicoureteral reflux (VUR) between the overactive and underactive bladders in patients with spinal cord injury who presented with VUR.

Methods: A total of 28 (13 cases of detrusor overactivity and 15 detrusor underactivity) men were enrolled. We compared the urodynamic variables between the two groups; detrusor pressure and bladder compliance, the infused volume at the onset of VUR measured on a voiding cystourethrography and cystometric capacity, maximum detrusor pressure, and bladder compliance during filling cystometry were recorded.

Results: At the onset of VUR, the bladder volume and compliance, except for the detrusor pressure, showed a significant difference between the two groups. The detrusor pressure, bladder volume, and bladder compliance relative to the cystometric capacity showed a significant difference between the two groups. The detrusor pressure, bladder volume, and bladder compliance at the onset of VUR relative to the cystometric bladder capacity did not show any significant difference between the two groups.

Conclusion: There were differences in some variables at the onset of VUR depending on the type of neurogenic bladder. The VUR occurred at a lower capacity in neurogenic bladder with detrusor overactivity than in neurogenic bladder with detrusor underactivity at the same pressure. VUR occurred at a lower intravesical pressure compared to that known as the critical detrusor pressure (≥40 cm H2O) required for the development of VUR. The results of our study demonstrate that the detrusor pressure should be maintained lower than the well known effective critical detrusor pressure for the prevention and treatment of VUR.