Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.
Issue link: http://todaysveterinarypractice.epubxp.com/i/715668
T O day' S Ve T erinary Prac T ice | September/October 2016 | tvpjournal.com i maging e SS en T ia LS Peer r eviewed 62 NORMAL ULTRASONOGRAPHIC FEATURES Urinary Bladder Bladder Wall Thickness n ormal bladder wall thickness in dogs is 1 mm, with thickness increasing mildly as body weight increases (see Measuring Urinary Bladder Wall Thickness in Dogs, page 61). i n cats, urinary bladder wall thickness ranges from 1.3 to 1.7 mm. The urinary bladder has irregular folds, which can be mistaken for abnormally thickened bladder walls when the bladder is relatively empty. i f an abnormality of the urinary bladder wall (eg, cystitis) is suspected, wall thickness may be confirmed by: • r e-examining the bladder at the end of the abdominal US examination • a dministering maintenance intravenous fluid or furosemide at low doses • Placing a urinary catheter to fill the bladder with sterile isotonic saline as needed. Evaluation of Bladder Structures The urinary bladder should be evaluated in long axis and short axis, from the apex to the level of the urethra at the ureterovesicular junction (Figure 1). i n male dogs, the prostate gland is immediately caudal to the urinary bladder. i n females, the urethra should be followed for several centimeters beyond the urinary bladder to evaluate for any abnormal urethral thickening or mineralization. The distal ureters (if seen) can be evaluated as they enter at the ureteral papillae, which are located along the dorsal urinary bladder wall adjacent to the cranial aspect of the trigone (Figure 2). Occasionally, echogenic ureteral jets may be seen entering the urinary bladder lumen at the level of the ureteral papillae secondary to ureteral peristalsis. 2,3 The histologic layers of the urinary bladder are difficult to define using US in a moderately distended urinary bladder. i f the layers are evident, they will consist of the following (Figure 2): • Outer serosal layer (hyperechoic) • Three smooth muscle layers (hypoechoic) • Lamina propria submucosal layer (hyperechoic), which parallels the inner mucosal layer (hypoechoic). Evaluation of Adjacent Structures The urinary bladder serves as a good acoustic window for adjacent structures, such as the colon, uterus (intact females), and iliac lymph nodes. a natomically, the urinary bladder is the most ventral structure in the caudal abdomen, followed by the Figure 2. Long-axis sagittal images of the ureteral papilla (arrowhead in A), normal wall layering ( B), and trigone region (C) of the urinary bladder in a dog. B C A Figure 1. Dorsal view of the distal ureters, urinary bladder, and proximal urethra.