F. Hansen et al., PRESSURE-FLOW STUDIES - AN EVALUATION OF WITHIN-TESTING REPRODUCIBILITY - VALIDITY OF THE MEASURED PARAMETERS, Neurourol. urodyn., 16(6), 1997, pp. 521-532
The within-examination variation in selected test parameters in repeal
ed pressure-flow studies was determined in a retrospective study of co
nsecutive pressure-flow examinations in 105 patients. It was further e
valuated to see whether then was a systematic change in the measured p
arameters during retesting. To see if variation and reproducibility we
re influenced by the procedure of investigation, i.e., transurethral o
r suprapubic, patients were grouped according to the method employed.
Finally, the effect of detrusor instability on the measurements was ev
aluated. Using the Abrams-Griffiths nomogram, patients were classified
as obstructed, equivocal, or unobstructed. The test-retest variations
in classification were evaluated. We found a systematic variation in
P-det.Qmax, P-det.Open, and Q(max) during testing, indicating a physio
logical effect of repeated pressure-flow studies resulting in a less o
bstructed second voiding. Accordingly, 69% of the patients who shifted
group of classification during retesting shifted to a group of lesser
obstruction at the second voiding. Still, 88% of patients remained in
the same group of classification of bladder outlet obstruction. Withi
n- and between-patient variations and reproducibility of the test resu
lts were not influenced by the procedure of investigation, i.e., the t
ransurethral or suprapubic method. However, we found variations sugges
ting a decrease in urethral resistance and bladder contractility from
test to test in the transurethral group, whereas variations suggesting
an isolated decrease in bladder contractility were seen in the suprap
ubic group. Detrusor instability per se does not seem to cause any sys
tematic changes during repeated testing. (C) 1997 Wiley-Liss, Inc.