The objective of this study was to identify differences in bladder shape changes between individuals with overactive bladder (OAB) and unaffected individuals during ultrasound urodynamics.
A prospective urodynamic study was performed with concurrent transabdominal ultrasound (ultrasound urodynamics) on individuals with and without OAB based on validated International Consultation on Incontinence Questionnaire - OAB survey scores. Three-dimensional ultrasound images were acquired at 1-minute increments during filling and used to measure bladder diameters in the height, width, and depth orientations. The engineering strain for each diameter was compared between participants with OAB and controls during urodynamic filling. The height-to-width ratio at capacity was used to determine if individuals were shape outliers.
A total of 22 subjects were enrolled, including 11 with OAB and 11 without OAB. During urodynamic filling in both groups, the greatest degree of geometric strain was found in the height orientation, indicating that bladders generally fill in a craniocaudal shape. The mean ± SD height-to-width ratio of the control group was 1.06 ± 0.12 yielding a 95% confidence interval of 0.82 to 1.30. Five (45.5%) of 11 OAB subjects had height-to-width ratios outside this interval as compared with none of the control subjects, identifying a potential shape-mediated subgroup of OAB.
Three-dimensional ultrasound urodynamics can be used to identify differences in bladder shape comparing individuals with and without OAB. This method may be used to identify a subset of OAB patients with abnormal bladder shapes which may play a role in the pathophysiology of their OAB symptoms.
From the *Department of Obstetrics and Gynecology, Virginia Commonwealth University Health System;
†Department of Mechanical and Nuclear Engineering,
‡Department of Biomedical Engineering,
§Department of Anatomy and Neurobiology, Virginia Commonwealth University;
∥Department of Radiology,
¶Female Pelvic Medicine and Reconstructive Surgery Division, Department of Obstetrics and Gynecology, and
#Division of Urology, Department of Surgery, Virginia Commonwealth University Health System, Richmond, VA.
Correspondence: Adam P. Klausner, MD, Division of Urology, Department of Surgery, Virginia Commonwealth University Medical Center, Box 980118, Richmond, VA 23298-0118. E-mail: firstname.lastname@example.org.
Research funding for this study was provided by the Virginia Commonwealth University College of Engineering Dean's Undergraduate Research Initiative and National Institutes of Health grant R01DK101719.
The authors have declared they have no conflicts of interest.