Normal Bladder Scan Volume After Foley Catheter Removal
A normal post-void residual (PVR) bladder volume after Foley catheter removal should be less than 100 mL as measured by bladder scan ultrasound. This threshold is widely used in clinical practice to determine adequate bladder emptying and to guide decisions about the need for re-catheterization.
Assessment of Bladder Volume After Foley Removal
- Bladder ultrasound scanning is a quick, safe, non-invasive, and comfortable method for assessing post-void residual volume after Foley catheter removal 1
- Bladder scanning shows high correlation (r = 0.89) with catheterized volumes, with 91% specificity and 93.1% negative predictive value when using 100 mL as the cutoff for determining adequate bladder emptying 1
- When catheter volume >100 mL was used as the cutoff for determining the need for re-catheterization, bladder scan volume measurements showed 90% accuracy 1
Clinical Management Protocol
- Remove Foley catheter within 24-48 hours after placement when clinically appropriate to minimize risk of urinary tract infection 2
- After Foley removal, implement a voiding schedule with assessment of post-void residual volumes 2
- For patients with post-void residual volumes consistently <100 mL, no further intervention is typically needed 1
- For patients with post-void residual volumes >100 mL, consider re-catheterization or implementation of intermittent catheterization 2
Special Considerations
- Repetition of ultrasound scan in patients who had an initial scan volume of <100 mL yields a 97.2% specificity and 100% negative predictive value in predicting catheter volume of <100 mL 1
- Traditional Foley catheter drainage systems may not completely empty the bladder, with studies showing mean residual volumes of 96-136 mL in hospitalized patients with indwelling catheters 3
- The accuracy of bladder volume measurements can be affected by patient factors such as obesity, ascites, and the presence of an indwelling catheter 4
Potential Pitfalls and Caveats
- Bladder scanners may overestimate bladder volume compared to actual catheterized volume, with a mean difference of approximately 21.5 mL in some studies 5
- Significant discrepancies between bladder scanner and ultrasound measurements have been observed in certain patient populations, particularly those with obesity, ascites, or indwelling catheters 4
- Despite these limitations, a recent CT imaging study found that the vast majority (97.6%) of patients with properly placed Foley catheters had adequately drained bladders with volumes <50 mL 6
Monitoring Protocol After Foley Removal
- Perform bladder scan after first void following catheter removal 2
- If post-void residual is <100 mL, continue normal voiding with periodic monitoring 1
- If post-void residual is >100 mL, consider implementing intermittent catheterization every 4-6 hours until volumes are consistently below threshold 2
- For patients with neurogenic bladder, continue catheterization until bladder volumes are consistently less than 30 mL for 3 consecutive days 2