Point of Care Ultrasound (PoCUS) is an efficient way to assess bladder volume. It is non-invasive and can be completed within minutes.   Further, POCUS can be performed at the bedside and is easily repeatable to monitor changes in bladder volume or confirm proper Foley catheter placement. 

In this module we will concentrate on the utilization of PoCUS specifically for the evaluation of bladder volume. While PoCUS offers a wide array of urologic applications, our focus will be narrowed to this key area. 

 

 

Why Ultrasound? 

PoCUS is beneficial as it enables rapid, bedside assessment of bladder volume and can guide immediate clinical decisions [1]. It allows for assessment of urinary retention and verification of lower urinary tract drainage—such as confirming appropriate Foley catheter function—and may guide interventions such as catheter repositioning or replacement. In addition, bladder PoCUS  can be used in repeat assessments in response to any clinical changes in the patient’s condition [1,2], and has also been shown to improve workflow efficiency in pediatric settings by helping clinicians determine whether a child’s bladder is sufficiently full before sending them for formal, radiology-performed pelvic and appendicitis ultrasounds—particularly in female patients, where a distended bladder is often required for optimal diagnostic imaging [3,4] 

Some studies suggest that PoCUS for bladder volume may be more accurate or reliable than automated bladder scanners, as it allows for direct visualization of the bladder and surrounding anatomy, reducing the risk of misidentification and improper bladder volume calculations [1,5]. Evidence comparing the accuracy of bladder volume PoCUS to catheterization volume in pediatric patients is limited, however, in adult populations, sensitivity and specificity of bladder volume PoCUS measured against catheterization volume ranged from 0.67 to 0.97 and 0.63 to 0.97, respectively, with mean values of 0.83 (SD = 0.12) for sensitivity and 0.80 (SD = 0.12) for specificity, based on eight studies [6]. Additionally, PoCUS assessment of bladder volume and post-void residual (PVR) prior to attempting urethral catheterization has been shown to prevent failed attempts and unnecessary repeat catheterizations in children [7,8]. The interobserver reliability for both post-void residual volume and full bladder volume measurements using PoCUS in pediatric patients has been shown to be strong—even among operators with differing levels of training—further supporting its utility in clinical settings [9]. 

While ultrasound is a valuable tool for evaluating bladder abnormalities, including changes in wall thickness, abnormal contents, bladder stones, and ureteroceles, a detailed discussion of these pathologies is beyond the scope of this module.