An individual is considered to have recurrent urinary tract infections (rUTIs) if they experience symptomatic UTI on two or more occasions within the preceding six months or three or more infections within the last 12 months. Urinary tract infections (UTIs) represent the most prevalent outpatient infection, with a lifetime incidence ranging from 50% to 60% among adult women. The incidence of rUTIs in women stands at 3%, translating to over 300,000 affected adult females annually in the UK (1). While acute UTIs are typically straightforward to manage, recurrent UTIs present a significant clinical challenge and have a considerable burden on affected individuals, leading to potentially serious clinical sequelae, decreased quality of life and increased healthcare costs. Video-urodynamic studies (vUDS) are the preferred diagnostic tool for identifying lower urinary tract dysfunction and assessing bladder storage and emptying function. However, descriptions of vUDS findings in patients with recurrent UTIs remain poorly elucidated, and the utility of these investigations is contentious due to the accepted risk of acute UTI as a complication of vUDS. This study aimed to compare vUDS findings of patients with and without a history of rUTIs.

This study was conducted as part of a service evaluation utilising the urodynamic database and performed as a retrospective case-control study of women with and without a self-reported history of rUTIs. The diagnosis of rUTIs was made using the standard recommended by the European Association of Urology (EAU) Guideline on Urological Infections, defined as two or more episodes of symptomatic UTIs within six months or three or more UTIs within 12 months (2). All vUDS were reviewed in standard fashion. Women over the age of 18 were included. Patients with known neurogenic lower urinary tract dysfunction were excluded. Demographics, past medical and surgical history, and urodynamic studies were compared between women with and without a self-reported history of rUTIs. Statistical analysis was performed using the Statistical Package for Social Science (SPSS) version 29.0

In total, 2070 cases were recorded within the urodynamic database. After excluding missing data and neurogenic lower urinary tract dysfunction, 2010 cases were included in our analysis. 240 (11.9%) had a history of rUTIs, and 1770 were UTI-free and deemed the control group. The mean age of each group was 51.9 years (range 18-88) and 52.9 years (range 18-92).  A homogeneous population with similar demographics and past medical and surgical history existed. Dyslipidaemia was statistically more common in women with a history of rUTIs, 11.9% versus 6%, OR 2.1 (1.3 – 3.5, 95% CI) (Table 1).

As demonstrated in Table 2, Qmax, MCC, Pdet opening, and Pdet Qmax were similar between both cohorts. Participants with a known history of rUTIs had higher PVR 46.63 +/- 89.4 SD versus 23.3  +/- 60.6 SD, p <0.001. During secondary analysis of urodynamic parameters (Table 3), women with a history of rUTIs were statistically more likely to have a PVR of greater than 50ml and 100ml, 30.9% versus 14.8%, OR 2.56 (1.89 – 3.50, 95% CI) and 15% versus 8.2%, OR 1.97 (1.32 – 2.93, 95% CI) respectively. Detrusor overactivity was recorded in 35.7% of cases, but no significant difference existed between cohorts. At cystourethrography, bladder morphology was abnormal in 15.4% compared to 14.5% in the non-rUTIs group. The documented abnormalities in bladder morphology are outlined in Table 4.

The study reveals a significant prevalence of lower urinary tract dysfunction among women with recurrent UTIs, with 35.7% exhibiting detrusor overactivity (DO). Repeated uninhibited detrusor contractions leading to inadequate blood flow can induce ischemia of the bladder mucosa, compromising the integrity of the urothelium.  This process potentially facilitates the penetration of uropathogens through the bladder barrier, thereby heightening susceptibility to rUTIs (3). Addressing DO through appropriate treatment could mitigate the frequent occurrences of elevated intravesical pressure resulting from uninhibited detrusor contractions, thereby reducing the likelihood of ischemia and potentially alleviating the burden of rUTIs. Moreover, the literature, albeit minimal, consistently suggests that an increased PVR volume is associated with rUTIs, a conclusion supported by our study. Our study expands upon these findings by demonstrating that even modest residual volumes, as low as 50ml and 100ml, pose a risk for rUTIs, suggesting that even minimal retained urine may serve as a reservoir for microbial proliferation.

This study, representing the largest cohort to date, elucidates the correlation between vUDS parameters in women with rUTIs and those without UTIs. The findings underscore the potential coexistence or contributory role of lower urinary tract dysfunction in rUTIs, emphasising the need for comprehensive vUDS assessment and tailored treatment of underlying pathology in affected women to mitigate the burden of rUTIs. Given the substantial overlap in lower urinary tract symptoms and acute bacterial UTIs, comprehensive investigation for alternative pathologies is essential as treatment approaches may vary. This is especially important when considering antibiotic stewardship, particularly in an era when the initiation of antimicrobial treatment for UTI can be based solely on symptoms without necessitating a positive urine culture. Considering vUDS is recognised as the most specific and accurate method for investigating potential lower urinary tract dysfunction, its inclusion in the diagnostic armamentarium for women with rUTIs merits re-evaluation in forthcoming guideline reviews. Should UDS be deemed necessary, consideration should be given to incorporating cystourethrography during the procedure, as 15.4% of the participants exhibited abnormal bladder morphology on imaging.

Butler, C. C., Hawking, M. K., Quigley, A. & McNulty, C. A. Incidence, severity, help seeking, and management of uncomplicated urinary tract infection: a population-based survey. Br J Gen Pract 65, e702–e707 (2015)
EAU Guidelines. Edn. presented at the EAU Annual Congress Paris 2024. ISBN 978-94-92671-23-3.
Bjorling, D. E., Wang, Z.-Y. & Bushman, W. Models of inflammation of the lower urinary tract. Neurourol Urodyn 30, 673–682 (2011).

Continence 12S (2024) 101457
DOI: 10.1016/j.cont.2024.101457