The incidence of urinary tract infections (UTI) is high in women and a proportion of women has recurrent UTI's. The standards in our country recommend referral to medical specialist care when UTI's recur more than 4 times per year or when UTI does not cure on usual antibiotics or recurs within a short interval. Medical specialist care guidelines are of the view that for patients referred with RUTI (cited from EAU-guideline): ... 'An extensive routine workup including cystoscopy, imaging, etc. is not routinely recommended as the diagnostic yield is low.' There is evidence for the very modest (positive and or negative) predictive value of cystoscopy or imaging in unselected women, however these modalities are recommended for specific indications. A recent study (1) (PMID: 30016804) included 12 studies for recurrent simple UTIs in a systematic analysis. These showed that (only) <1.5% of (656 reported total) women investigated with imaging or cystoscopy had life-threatening (0.15% (1) malignancy and few fistulae) pathology, but up to 67% had abnormal urodynamics; abnormal flowrate and or PVR. Only 2 studies in this review have reported the use of invasive urodynamics and especially DO has been an incident observation (≈50%) in small cohorts. Apart from these small studies the prevalence of lower urinary tract dysfunction in the cohort of women with RUTI is not reported. 
On the other hand: In the era of increased attention to the urinary tract micobiome and lower urinary tract (LUT) (dys)function the association of LUTD and ‘common’ recurrent urinary tract infections (RUTI) is potentially relevant. Many reports suggest an association of bacterial DNA and or evidence for bladder microbiome with symptoms of dysfunction and ICI-RS suggests further research. (2,3) (PMID: 28444712 & 30133786). We report objective assessment of LUTD in a large cohort of women with RUTI with the aim to explore the relevance of RUTI for LUTD dysfunction. To this aim we have also included an age matched cohort of women with signs and symptoms of LUTD without a history of (R)UTI.

We included 208 women with mean age 51,5, range 19-96. All women had RUTI according to our national standard criteria; 43 (21%) had a uro-(gynecol-)logical history (UrolHist) (e.g. vaginoplasty, hysterectomy or vesicourethral reflux). All women underwent (invasive) urodynamics, after guideline-compatible assessment of symptoms and clinical assessment. Urodynamics (fluid fill, external pressure, urethral double lumen F8) was done when the patients had no signs or symptoms of urinary tract infection with the patient seated, after the insertion of the catheters. Cystometry was done with room temperature saline up to to strong desire to void (taking into account the data from the bladder diary). Voiding was allowed in seated position and in privacy. PVR was measured via the urodynamic catheter after voiding.
821 age matched female patients with symptoms of LUT dysfunction without history of UTI’s were used as an otherwise unselected control cohort from our department, with identically performed urodynamics. The overall prevalence of DO in this 'random' control cohort of referred patients is 56.7%; the prevalence of underactive detrusor (DU) is 23,7% and bladder outflow obstruction (BOO) 1%.

Table 1:

The table shows that RUTI patients with or without UrolHist did not differ (t-tested:) in flowrate, voided volume, cystometric capacity, outflow resistance (BOO) or detrusor contraction. Although detrusor overactivity (DO) was associated with reduced (urodynamic and bladder diary) capacity the incidence of DO was similar in the groups with (58%) or without (56%) UrolHist.
Five (3.6%) patients without and 2 (5%) with UrolHist had bladder outflow obstruction (URA>30) and 26% and 30% had DU. The average contractility was lower in advanced age and weakly (chi2 .025) associated with DO. DO was also somewhat more incident (chi2 .031) in patients with higher grade of BOO.
Comparing this to the non RUTI control group shows that the percentages DO and DU are remarkably similar to the RUTI -group.

Patients that have no abnormalities on function testing were offered RUTI management as per current practice guidelines. Sometimes the studies provide arguments to advise to reduce too excessive fluid intake. Patients however, that have shown (concurrent? causative? resulting?) LUT dysfunction are offered specific management for the dysfunction as well.
The relevance of these observations probably twofold: Female RUTI can (or should?) be interpreted more as a sign of lower urinary tract dysfunction than as a sign of anatomical abnormalities and it should be considered to adapt the guidelines accordingly. 
The other implication may be that epidemiological studies to show an association between microbiome or common UTI and LUTD or symptoms need samples that are large enough to correct for the 'background prevalence' of LUTD or symptoms.

Recurrent urinary tract infection is less likely a sign of anatomical abnormalities than of dysfunction. Imaging provides less likely useful information than assessment of function.
Referred patients with RUTI with or without a history of urogynecological interventions or abnormalities have a prevalence of LUT dysfunction that, when assessed objectively, is high, and similar to patients who are referred with symptoms of LUT dysfunction without recurrent urinary tract infections.

Santoni N, Ng A, Skews R, Aboumarzouk OM. Recurrent Urinary Tract Infections in Women: What Is the Evidence for Investigating with Flexible Cystoscopy, Imaging and Urodynamics?. Urol Int. 2018;101(4):373–381.
Drake MJ, Morris N, Apostolidis A, Rahnama'i MS, Marchesi JR. The urinary microbiome and its contribution to lower urinary tract symptoms; ICI-RS 2015. Neurourol Urodyn. 2017;36(4):850–853.
Ford AA, Veit-Rubin N, Cardozo L, Khullar V. Is the microbiome influencing patient care in lower urinary tract dysfunction? Report from the ICI-RS 2017. Neurourol Urodyn. 2018;37(S4):S93–S98.