Aims of Study
An ongoing study to determine the natural history
of men with lower urinary tract symptoms (LUTS)
has previously shown little deterioration in bladder
outlet obstruction (BOO) in patients treated conservatively,
and a long term reduction in BOO following TURP
(1). In order to describe the voiding function more
precisely, bladder outlet obstruction index (BOOI),
bladder contractility index (BCI) and bladder voiding
efficiency (BVE) were calculated. It has previously
been suggested that men with large residual urines
undergoing TURP have a failure of contractility,
possibly related to a widespread degeneration of
muscle cells and axons found in the elderly. However,
a large residual urine has subsequently been shown
to correlate with a high detrusor pressure at maximum
flow (pdetQmax), suggesting any decompensation by
the detrusor is not related to a fall in pdetQmax
(2). TURP has not been shown to improve detrusor
contractility in short term studies using the Hill
equation (3).
Methods
71 men treated conservatively and 126 men who
underwent a TURP for LUTS due to BOO were followed
up at least 10 years later (median 13 years). All
subjects were over 45 years of age, and underwent
pressure flow studies (PFS) initially and at follow
up, which included measurent of maximum flow rate
(Qmax), pdetQmax, voided volume (VV) and total bladder
capacity (BC) (voided volume + residual volume).
BOOI, BCI and BVE were calculated as:
BOOI = pdetQmax - 2Qmax
BCI = pdetQmax + 5Qmax
BVE = (VV/BC) x 100
Statistical analysis was performed using the
paired t-test for the normally distributed data,
and the Willcoxon signed ranks test for the BVE
data, as this was not normally distributed.
Results
The results are presented
in table 1 and 2 and show no change in the PFS measurements
for the conservative group, apart from a slight
reduction in BCI. There was a significant improvement
in all PFS measurements for the TURP group.
Table 1 Initial and follow
up PFS data for 71 men treated conservatively
|
|
Qmax
|
PdetQmax
|
BOOI
|
BCI
|
BVE
|
|
Initial PFS
|
9.8
|
85.4
|
66.2
|
134.1
|
89.9
|
|
Follow up PFS
|
9.2
|
80.1
|
62.1
|
125.8
|
84.7
|
|
P value
|
0.194
|
0.164
|
0.321
|
0.040
|
0.096
|
Table 2 Initial and Follow
up PFS for 126 men treated by TURP
|
|
Qmax
|
pdetQmax
|
BOOI
|
BCI
|
BVE
|
|
Initial PFS
|
7.5
|
100.5
|
85.7
|
137.9
|
76.8
|
|
Follow up PFS
|
12.2
|
45.3
|
22.8
|
107.1
|
91.4
|
|
P value
|
<0.001
|
<0.001
|
<0.001
|
<0.001
|
<0.001
|
Conclusions
The slight deterioration in BCI, without a
change in BOOI or BVE for the group treated conservatively,
suggests little change in voiding function, and
that untreated BOO does not lead to chronic retention.
The reduction in BCI and improvement in BVE
in the TURP group demonstrates a long term improvement
in voiding function. The change in BCI could represent
a long term improvement in contractility after TURP,
or could be due to a problem using this simple formula,
compared to more complicated methods of measuring
contractility.
References
1. Neurourol urodynam (1998)
Proceedings of the ICS. Abstract 51a and 51b.
2. Br J Urol (1987); 60:560-6
3. J Urol (1992); 148:1856-60
