A new technique for assessing detrusor leak point pressure in patients with spina bifida

We report a new modification of the technique used to measure detrusor leak point pressure in patients with myelodysplasia and discuss its clinical implications.

We assessed detrusor leak point pressure during standard multichannel urodynamics in 77 patients with spina bifida. At leakage and in the absence of a detrusor contraction detrusor pressure is noted and the catheter is removed. With the cessation of leakage the catheter is reinserted and detrusor pressure is again noted. This cycle is repeated several times and the average difference is noted. In 23 patients there was no identifiable detrusor leak point pressure. The remaining 54 patients with a detrusor leak point pressure are included in this report. Also reviewed were renal ultrasound studies and voiding cystourethrograms for each patient.

Three groups of patients were identified: 1 (20 patients)-detrusor leak point pressure greater than 40 and less than 40 cm. water with the catheter in and out, respectively; 2 (29)-detrusor leak point pressure consistently less than 40 cm. water with the catheter in and out, and 3 (5)-detrusor leak point pressure consistently greater than 40 cm. water with the catheter in and out. There was a 5% incidence of upper tract changes in group 1 and a 40% incidence in group 3. All patients in group 2 had normal upper tracts.

A difference in upper tract changes was noted between groups 1 and 3, although in both groups detrusor leak point pressure was greater than 40 cm. water using standard measurement techniques and similar rates of upper tract changes would have been expected. Our modification may be a more accurate measurement of detrusor leak point pressure. It provides a better means of identifying patients at increased risk for renal deterioration and assessing outlet resistance.