SUFU 2019: Anatomical Characteristics of the Subtrigonal Zone as Potential Area for Novel Targeted Approaches to Treat Bladder Dysfunction: MRI Study in Females

Miami, FL ( In this study, Dr. Javaid and her team were trained by board-certified radiologists on how to read and take measurements on pelvic MRIs with and without contrast. Their study was based on the fact that magnetic resonance imaging (MRI) is used more frequeantly for the evaluation of the female pelvis. MRIs allow for improved tissue characterization due to high-contrast resolution. Recent studies show the subtrigonal region to be richly innervated and new localized therapies have been tested to treat overactive bladder (OAB).  This region in fact, has been studied in the past for treatment of OAB. The aim of this study is to evaluate anatomic relationships in this region in order to aid in the development of emerging therapies in the treatment of OAB.

This is a retrospective study of female patients 18 or older who underwent MRI of the pelvis with and without contrast at a single academic center. Two board-certified radiologists trained 3 data collectors on how to take MRI measurements. Measurements were standardized in sagittal and axial T2 images of the pelvis.  Data points in the sagittal plane 10 mm proximal from bladder neck include anterior vaginal wall thickness, bladder wall thickness and distance from vaginal epithelium to urothelium and urethral length. Demographics and history were obtained from electronic medical records including: date of birth, race, BMI, hysterectomy status, pelvic organ prolapse, urinary incontinence and fibroids. 

UroToday SUFU2019 Anatomical Characteristics of the Subtrigonal Zone 1

Measurements were compared using two-sample t test and ANOVA. Multivariable linear regression model was used to model the independent associations between measurements and patients’ characteristics.

300 MRIs were reviewed and 175 subjects were included in the analysis. Their significant findings include younger women < 45 had thicker anterior vaginal walls and longer distance from vaginal epithelium to bladder urothelium. Obese females had thicker anterior vaginal walls, a smaller urethral width was associated with fibroids. They also found that Asian and African American subjects had thicker bladder walls and they did not find a difference in the subtrigonal space were seen in other conditions (hysterectomy, pelvic organ prolapse, incontinence of any type)

In conclusion, this study shows that younger, premenopausal women have significant variability in the thickness of the vaginal epithelium to the trigone. Understanding the characteristics will aid in development of targeted therapeutic approaches to treating overactive bladder in women. They would like to continue this project and collect more patient data and work on developing a new technique to approach the nerves in this subtrigonal region for the treatment of OAB.

Presented by Naila Javaid, MD, University of California Irvine Department of Urology