Indications Urinalysis is critical in evaluating and treating patients with suspected urinary tract infections or complex urosepsis. Urethral catheterization is a standard method for obtaining urine samples, but is not always possible or successful. Ultrasound evaluation of bladder volume has been shown to significantly improve catheterization success rates in childrenwhencompared to blind catheterization (1,2). Urethral catheterization may not be possible secondary to obstruction (e.g., prostatic hypertrophy, urethral stricture), or it may be contraindicated secondary to trauma (e.g., suspected urethral injury). Placement of a suprapubic catheter for bladder decompression is indicated in such cases. Ultrasound guidance for suprapubic bladder catheterization has been shown to improve success rates, decrease number of attempts, and decrease complications (3-9). Anatomical Considerations The urinary bladder is protected by the pelvis in adults and older children. In younger children, the bladder may extend into the abdomen. Anechoic urine provides an excellent acoustic window, and the bladder, with rounded walls surrounding dark urine, is usually easy to visualize (Fig. 20.1). An empty bladder is more difficult to visualize, and sonographers should look for collapsed walls containing small amounts of urine (Fig. 20.2) similar to a collapsed gallbladder (see Chapter 14). Bowel gas may impede a clear view of the bladder.
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