Overactive bladder (OAB) is a prevalent condition that deteriorates the quality of life (QOL) of patients1. OAB has diverse etiologist, which include supra-sacral neurological diseases, metabolic syndrome, autonomic dysfunctions, and bladder outlet obstruction (BOO). In addition, a decreased level of estrogenic, bladder outlet incompetence and especially, pelvic organ prolapse (POP) are associated with the pathophysiology of female OAB2. Overactive bladder (OAB) is a prevalent condition, which negatively impacts patients’ quality of life. Pelvic organ prolapse (POP), also prevalent in women, has been recognized as an important ethology of female OAB, although the pathophysiological mechanisms remain controversial.

In this study, the dynamic magnetic resonance imaging (DMRI) in 118 patients with POP and investigated the association between DMRI findings, including positions and motilities of pelvic organs as well as parameters of pelvic organ support and bladder outlet obstruction (urethral kinking), and OAB in order to elucidate the pathophysiology of OAB in patients with POP.

Our results showed that compared with non-OAB patients, OAB patients had a significantly higher body mass index, more severe pelvic floor muscle impairment, and more profound supportive defects in the uterine cervix apical compartment. On the other hand, DMRI parameters showed hardly any significant difference between patients with mild and moderate to severe OAB. These findings may imply that elevator any impairment and defective supports of the apical compartment could be associated with the presence of OAB and that the severity of OAB could be affected by factors other than those related to pelvic organ mobility and support or urethral kinking.

This study has several limitations. First, DMRI was performed in a supine, rather than a standing, position because our magnetic resonance imaging (MRI) equipment did not allow upright examination. Also, we did not measure intra-abdominal pressure during the Valsalva man oeuvre. However, DMRI was conducted by one specialized and experienced technician with a consistent protocol, and we included only patients who were able to reproduce POP stage II during straining. Second, we measured POMs with coordinates of selected landmarks at rest and during straining. Strictly speaking, the coordinates at rest would not correspond to the “normal positions” of the patients.

However, we do not have data on the “normal positions” because we have not performed DMRI on nulliparous women without any symptoms, and a definition of the “normal positions” on DMRI of Asian women has not been established. Moreover, POMs should be adjusted to the patient’s height or pelvic bone geometry. However, use of these corrected methods is not widespread yet. Third, we included patients with POP stage II at rest and POP stage II during straining. Therefore, we did not evaluate the association between mild (stage II during straining) POP and OAB as well as between severe POP and OAB. Fourth, we have not taken MRIs of patients after POP repair. Therefore, we did not investigate whether decreased POMs after POP repair correlated with the improvement of OAB.

In conclusion, considering the parameters derived from DMRI, elevator any impairment and defective supports of the apical compartment were associated with the presence of OAB, while almost all parameters derived from DMRI were not associated with the severity of OAB, which could be affected by systemic factors.

Journal of Nephrology and Urology is an Open Access peer-reviewed publication that discusses current research and advancements in diagnosis and management of kidney disorders as well as related epidemiology, pathophysiology and molecular genetics.

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Regards
Mercy Eleanor
Editorial Assistant
Journal of Nephrology and Urology