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Purpose: Urinary tract infection (UTI) has been identified as the most common hospital-acquired infection in the United States. Studies have shown that UTIs are significantly more common after colorectal surgery, especially rectal surgery, compared with other procedures. We hypothesized that the use of ureteral stents in rectal surgery would be associated with a higher risk of UTI. We also sought to examine other risk factors for UTI after rectal surgery
Methods:
All patients undergoing rectal resection at a tertiary care medical center from 2005 to 2010 were identified using ICD-9 procedure codes. Patient and procedure variables, UTI within 30 days of surgery, urinary retention (defined by reinsertion of a Foley catheter), major complications, and length of stay (LOS) were identified on retrospective chart review. UTI was defined as a positive urine culture with >105 colonies/ml urine with no more than 2 species of organisms and one of the following: fever >38 degrees C, urgency, frequency, dysuria, or suprapubic tenderness. Prolonged LOS was defined as > 75th percentile and was >10 days in this cohort. Comparisons between groups were made with Student t tests and Fisher exact tests (alpha = 0.05). Multivariable analysis of significant factors (p<0.2) was performed with stepwise logistic regression. All statistical analyses were performed using SAS 9.2 (Cary, NC).
Results:
We identified 223 patients during the study period with age range of 18 to 96 (median 63). There were 110(49%) males. Ureteral stents were used in 36 cases (16%). The majority of patients had rectal cancer as the primary diagnosis (52%), followed by inflammatory bowel disease (26%), and rectosigmoid cancer (5%). UTI occurred in 9%, and urinary retention occurred in 21%. UTI rates were the same in stent and no stent groups (9% vs. 9%, p=1). In multivariate analysis, females older than 65 (OR 5.2, 95% CI 1.63-16.64), higher estimated blood loss (OR 1.9, 95% CI 1.07-3.37), and a diagnosis of depression (OR 4.7, 95% CI 1.58-14.0) were independently associated with UTI (model c=0.78). UTI+ patients were more likely to have a prolonged LOS (p=0.04) and be discharged to a rehab facility (p=0.01), but not more likely to have associated major complications (p=1).
Conclusion: Ureteral stents are not associated with a higher rate of UTI in patients undergoing rectal resection. Females older than 65, a higher estimated blood loss, and a diagnosis of depression were found to be independent significant predictors of UTI. We have no clear explanation for why depression would be associated with UTI and it should be studied further in postoperative patients.
RIsk Factors for UTI in Rectal Surgery Patients

Variable, n(%)	UTI+ (n=20)	UTI- (n=204)	p-value
Age, mean y (SD)	59.7(16.2)	52.6(15)	0.05
Female	14(70)	96(48)	0.10
Female age >65	6 (30)	17(8)	0.01
BMI >30	5(25)	69(30)	0.80
ASA class >3	9(45)	62(35)	0.359
Rectal Cancer	7(35)	110(54)	0.16
Inflammatory bowel disease	6(30)	53(26)	0.79
Depression	7(35)	20(10)	0.005
Diabetes mellitus	4(20)	19(9)	0.13
Laparoscopic surgery	3(15)	25(12)	0.72
Ureteral Stent	3(15)	33(16)	1.0
EBL* cc(95%CI)	509 [340-760]	330 [290-376]	0.05
Operative duration >300 min	12(60)	69(38)	0.06
Urinary retention	6(30)	41(20)	0.39

*EBL was analyzed after logarithmic transformation (ln) to create a normal distribution