Is Methenamine Prophylaxis for Urinary Tract Infection After Midurethral Sling as Effective as Antibiotic Prophylaxis?

Synthetic polypropylene mid-urethral slings (MUS) are the gold standard for treatment of stress urinary incontinence (SUI). The most common post-operative complications are urinary tract infection (UTI), bladder injury, bleeding, and mesh erosion. Amongst these complications, post-operative urinary tract infections are the most common complication with incidences up to 21-34%. With high incidences in post-operative UTI, previous studies have shown evidence for the use of prophylactic antibiotics after MUS placement. Previous studies have demonstrated prophylactic antibiotics after MUS placement decreased the incidence of post-operative UTI in the treated groups. While the use of post-operative prophylactic antibiotics may decrease the risk of post-operative UTI, it is essential to consider the broader implication of such antibiotic use.

Along with increased antibiotic use, there is an increase in multidrug resistant uropathogens. This has led to an increased emphasis on antibiotic stewardship to optimize patient care by minimizing the risk of developing antibiotic resistant organisms, preserving effectiveness of currently used antibiotics, and promoting appropriate prescribing practices. There are no studies evaluating post-operative UTI prophylaxis after MUS with methenamine.

Methenamine is a urinary antiseptic that acts when methenamine is converted to ammonia and formaldehyde, which denatures bacterial proteins and nucleic acids. There is no evidence of bacterial resistance to methenamine. Methenamine has been shown to be non-inferior to antibiotic prophylaxis in the setting of recurrent UTI. Methenamine has most commonly been used as long-term UTI prophylaxis treatment, but there are studies demonstrating benefit from short-term methenamine use for prophylaxis.

The investigator's aim is to evaluate whether methenamine is non-inferior to antibiotic prophylaxis after MUS procedure in preventing post-operative UTI.

Inclusion criteria

• Female
• Age ≥ 18
• Patients undergoing mid-urethral sling procedure

Exclusion criteria

• Medication intolerance or allergy to study medications
• Renal impairment with GFR <30
• Breast feeding
• Pregnancy
• Recurrent urinary tract infections
• Active urinary tract infection
• Immunosuppressive disease
• Interstitial cystitis