For female patients with lower urinary tract symptoms, urodynamic studies provide limited information for evaluating bladder function as a predictor of successful trial without catheter (TWOC). Early removal of the Foley catheter could reduce catheter-related complications, such as urinary tract infections. This study aimed to measure the posterior wall of the urinary bladder by transvaginal ultrasonography, investigating blood flow, thickness, and stiffness (measured by shear wave velocity, SWE) of detrusor muscle, in women with acute or chronic urinary retention under different degrees of bladder filling, for investigating the different biochemical characteristics of the urinary bladder.

During the period from October of 2020 to January of 2023, women with chronic urinary retention, with first episode of acute urinary retention, without Foley catheter. Transvaginal ultrasound were performed by using an ultrasound machine (Aplio i-Series A800, Canon Medical System) with a transcavitary curvilinear probe (3 to 11 mHz) equipped with SWE. We measured the bladder wall blood circulation (Resistive Index, RI), using Duplex Doppler ultrasound. Detrusor wall thickness (DWT) and SWE of posterior bladder wall were acquired sequentially starting from empty bladder, different degrees of bladder filling (50ml, 100ml, 150ml, 200ml), and once again empty bladder.

The mean age was 70.4±9.1 years old for patients with AcB/DU, 69.0±10.9 years old for patients with detrusor normoreflexia. DWT decreases during the bladder filling, and no statistical difference was found between AcB/DU and normoreflexia. Patients with AcB/DU showed significantly greater resistive index (RI) at empty bladder. In AcB/DU, the mean shear wave modulus was higher than those with detrusor normoreflexia under distended bladder (at 100cc, 150cc and 200cc). The AcB/DU group also showed positive correlation between increased mean shear wave modulus and increased DWT at initial empty bladder (r=0.500, p=0.015), 150cc (r=0.716, p =0.001), 200cc (r=0.737, p =0.000) and second-time empty bladder (after distention) (r=0.397, p=0.033). We also observed, although not statistically significant, a trend of negative correlation between DWT and stiffness in women with detrusor normoreflexia under distended bladder (at 150cc, r= - 0.196, p=0.466; at 200cc, r= -0.181, p=0.472).

The higher resistive index in AcB/DU indicated bladder ischemia and bladder dysfunction. Both mean DWT of AcB/DU and detrusor normoreflexia became thinner under bladder distention.

AcB/DU women had poor blood flow and a significant increase in detrusor stiffness under bladder distention. Even under thinner detrusor, there is a positive correlation between DWT and stiffness in women with AcB/DU. This finding may be explained by fibrotic changes of detrusor muscle that resulted in AcB/DU. In summary, shear wave elastography is a feasible and reliable tool for predicting AcB/DU. The image findings could well explain the bladder function as a predictor of successful trial without catheter (TWOC).

Volikova AI, Marshall BJ, Yin JMA, Goodwin R, Chow PE, Wise MJ. Structural, biomechanical and hemodynamic assessment of the bladder wall in healthy subjects. Res Rep Urol. 2019 Sep 3;11:233-245. doi: 10.2147/RRU.S205383. PMID: 31565652; PMCID: PMC6732741.