Abstract
Background: Preoperative bladder urine culture (PBUC) analysis
has become a standard application before any stone surgery. When growth
is detected in PBUC, it is contraindicated to perform flexible
ureterorenoscopy (f-URS). The results of the PBUC susceptibility test do
not correlate well with those of the renal pelvic urine culture (RPUC)
analysis. Previous studies have demonstrated the positivity of RPUC as
an important marker for the development of infections after endoscopic
operations. In the current study, we aimed to evaluate the consistency
between PBUC and RPUC and to identify preoperative markers associated
with a positive RPUC.
Methods: 129 patients who underwent f-URS on renal and proximal
ureteral stones in two centers between 2015 and 2020 were prospectively
recorded in a database and retrospectively analyzed. PBUC was obtained
from all the patients preoperatively, and RPUC was taken at the
beginning of the f-URS operation. The results of the two cultures were
compared.
Results: There was growth in PBUC in 25 (19.4%) patients and
RPUC in 35 (27.1%) patients. Possible predictive markers in predicting
a positive RPUC were evaluated using multivariate logistic regression
analysis. Preoperative urine density at the renal pelvis [odds ratio
(OR): 0.848, p<0.001p=0.001 ), and lower calyceal stone
localization (OR: 0.033, p=0.017 ) were determined as independent
predictive factors for a positive RPUC. The ability of pelvis urine
density to predict positive RPUC positivity was evaluated using the
receiver operating characteristic analysis, in which the area under the
curve value was determined to be 0.858 (0.780-0.936). The cut-off value
of pelvis urine density in the prediction of RPUC positivity was 4.5, at
which it had80% sensitivity and 77.7% specificity.
Conclusions: PBUC may not represent true colonization. Although
bladder urine culture is negative before the operation, patients with
preoperative hydronephrosis and low pelvis urine density may have RPUC
growth.
Keywords: Flexible ureterorenoscopy, urine culture, Urinary
tract infection, pelvis urine culture