Why men urinate more efficiently while standing than in a supine position: morphological analysis with real-time magnetic resonance imaging

Shimatani K1, Soufi M2, Sato Y2, Yamamoto S1, Kanematsu A1

Research Type

Pure and Applied Science / Translational

Abstract Category

Male Lower Urinary Tract Symptoms (LUTS) / Voiding Dysfunction

Abstract 428
Fistula, Diverticulum and Wild Card
Scientific Podium Video Session 26
Friday 9th September 2022
16:51 - 17:00
Hall G1
Anatomy Voiding Dysfunction Male Imaging
1. Department of Urology, Hyogo College of Medicine, 2. Division of Information Science, Graduate School of Science and Technology, Nara Institute of Science and Technology
In-Person
Presenter
Links

Abstract

Introduction
Few studies have examined the effects of body position on urination efficiency morphologically. We aimed to dissect out the anatomical changes of pelvic organs during urination in the upright and supine positions by a real-time magnetic resonance imaging (rtMRI) system.
Design
Thirteen healthy male volunteers aged 26-60 years were included in the study. The sagittal real-time 2D images were taken to evaluate urinary efficiency, along with change in five morphological indices at the time of storage and the beginning of voiding, in both upright ant supine positions.
Results
Urination was more efficient in upright position than in supine position, as expressed by higher average rate of bladder emptying (9.9±4.2 vs. 6.8±2.9ml/sec, p<0.05), and also by fewer participants showing significant residual urine (1/13 vs. 7/13, p<0.05). At the onset of voiding in standing position, the levator ani muscle moves downward and backward followed by descent of the bladder neck and rotation of the prostate around the symphysis. Such changes were expressed by two morphological indices. One was posterior vesicourethral angle at the start of voiding, 152±7 vs. 140±1 in upright and supine position (p<0.05). The other index was the change in angle between levator ani line and pubo-coccygeal line in upright and supine position, 9.4±9.9 vs 1.6±7.9 before voiding (p<0.05), and 30.2±14.0 vs 17.3±12.9 after the start of voiding (p<0.05).
Conclusion
This is, to our knowledge, the first report to capture the anatomical changes of pelvic organs during urination in the upright position. In addition, we introduced a novel parameter to quantify the dynamic relaxation of the levator ani as the angle LA/PC, which seemed to be a key movement related to efficient urination.
Disclosures
Funding This work was supported in part by a KAKENHI grant (no. 17K10164) and a grant from the Adaptable and Seamless Technology transfer program (A-step) (no. JPMJTM20FN) given to A.K. Clinical Trial No Subjects Human Ethics Committee The present study was approved by the ethics committee of Nara Institute of Science and Technology (2000-M-13). Helsinki Yes Informed Consent Yes
Citation

Continence 2S2 (2022) 100402
DOI: 10.1016/j.cont.2022.100402

14/10/2024 23:22:27