This is a study of patients undergoing gynecologic surgery who require post-operative catheterization to determine if prophylactic antibiotic treatment decreases the risk of post-operative urinary tract infection in these patients.

Study Population Participants will be recruited from all patients who are planning to undergo gynecologic surgery by an attending surgeon in the Division of Urogynecology at Duke University Medical Center (DUMC). After enrollment and randomization, the participants will take the study drug once daily to start on post-operative day one and continue until the participant has stopped catheterizing for up to one week after surgery. The participant will also complete a daily diary for one week after surgery to record any catheterization and any study drug or additional antibiotic medication taken. We will then follow patients for a total of three weeks after surgery to monitor for treatment for UTI. At three weeks after surgery the observation period for the participant is complete.

Sample Size Under the assumption of 80% power and an alpha error of 0.05, we would need 156 subjects to demonstrate a 66% reduction in risk of UTI (i.e. from 28% to 10%) in those undergoing prophylactic antibiotic treatment. Therefore, we aim to recruit a total of 175 participants to account for participant dropout.

Study Definitions For our study purposes, post-operative catheterization will be defined to include patients who are hospitalized post-operatively with an indwelling Foley catheter as well as patients discharged with either intermittent self-catheterization (ISC) or indwelling Foley catheter. The decision to catheterize will be determined by type of surgical procedure, need for inpatient stay and void trial results. Void trials will be conducted as follows: the bladder is backfilled with 300cc normal saline, the catheter is removed and the patient is prompted to void immediately and, after voiding is complete, a (PVR) post-void residual volume is measured. The patient passes the void trial if she voids over 200cc in total volume or if her PVR is less than 100cc.

Our primary outcome of treatment for UTI within the first three weeks after surgery is to be defined clinically. A patient will be considered to have received treatment for UTI if she receives any antibiotic therapy for clinically suspected or culture-proven urinary tract infection (i.e. empirically given upon development of urinary symptoms or prescribed based on urinalysis or urine culture results) within the first three weeks after surgery.

Data Collection Demographic characteristics, operative data and post-operative data will be collected. Prior to discharge after surgery all patients will undergo a void trial per standard procedure unless they receive an indwelling Foley catheter for overnight hospitalization. Post-operatively all subjects will be given a catheterization diary to record days of catheterization and days of antibiotic therapy. All subjects will be instructed to call our clinical office to report any urinary complaints and/or treatment for UTI. Information will be collected from electronic medical records regarding any office visits, urine cultures performed or treatment for UTI during this post-operative period. Data will be entered into a de-identified study database for analysis by the PI and study coordinator who will be blinded to participant randomization.

Subject Randomization and Blinding Study participants will be randomized to prophylactic treatment versus no treatment via a computerized randomization scheme by the IDS at the time of enrollment. Patients will be blinded to treatment by the utilization of placebo tablets.

Adverse Events Nitrofurantoin is FDA approved for the treatment of UTI. We will be using a prophylactic dose and will monitor for any adverse events. Adverse events will be reported per protocol. A safety monitoring designee will perform reviews on a designated basis throughout the study.

Study Costs There will be no additional cost to the patient for their participation in this study. No additional laboratory testing will be performed as a result of participation.

Inclusion Criteria:

• Undergoing urogynecologic surgery
• Receive postoperative catheterization

Exclusion Criteria:

• Age less than 21 years old
• Pregnancy
• Allergy, contraindication or intolerance to Nitrofurantoin
• Do not speak English
• Dependent on trans-urethral catheter to accomplish voiding preoperatively
• Undergoing interstim device placement, urethral diverticulum surgery or fistula surgery
• Sustain intraoperative urinary tract injury requiring postoperative catheterization

163 participants were randomized, 82 to nitrofurantoin and 81 to placebo. Four randomized participants were excluded from the final analysis. One in the placebo group was excluded, as she had previously been included in the study during a prior surgery. Three participants in the nitrofurantoin group were excluded due to protocol deviations.

20 months

Limitations of our study include recall bias and selection bias. Our findings have limited applicability to elderly patients undergoing pelvic reconstructive surgery.