Bladder scanning is a quick, safe, and non-invasive method for evaluating post-void residual (PVR) urine volume in patients with urinary disorders such as incontinence, retention, or overactive bladder. Unlike catheterization, which is accurate but invasive and uncomfortable, bladder scanning is widely tolerated by patients. This method helps prevent complications such as infections, renal impairment, and discomfort from bladder overdistension or unnecessary catheterization.
Table of Contents
- What is Bladder Scanning?
- Benefits
- Indications
- Interfering Factors
- Who Performs Bladder Scanning?
- Equipment
- Steps on Assessing Bladder Volume Using a Bladder Scanner
- Bladder Scanning Results
- Nursing Considerations
- Sources
What is Bladder Scanning?
Bladder scanning is a noninvasive diagnostic procedure that uses ultrasound waves to assess the volume of urine in the bladder. A bladder scanner is a portable, hand-held device that provides real-time, quantitative measurements of bladder volume expressed in milliliters (mL). The process is painless and fast, and the risks associated with catheterization are avoided.
Benefits
Bladder scanning is preferable to other interventions for assessing post-void residual volume, including intermittent catheterization.
- Non-invasive and painless. Provides a safe and comfortable option, particularly for patients at high risk of infection or trauma, such as the elderly or immunocompromised individuals.
- Real-time assessment. Provides immediate results to guide clinical decisions in emergency and acute care settings, such as for patients in pain or with suspected urinary retention.
- Portable equipment. Bladder scanners are compact and can be used at the bedside.
- Accurate measurements. Useful for quantifying post-void residual (PVR) urine.
Indications
Bladder scanning is performed to assess bladder function and identify abnormalities. Key indications include:
- Measures post-void residual (PVR) volume in patients with incomplete bladder emptying. It is useful for diagnosing bladder outlet obstruction, detrusor muscle weakness, or neurogenic bladder caused by conditions such as spinal cord injuries or multiple sclerosis.
- Determines whether catheterization is necessary for urine drainage.
Reduces the risks of catheter-associated urinary tract infections (CAUTIs) and urethral trauma, especially in patients with temporary or fluctuating urinary retention. - Assists in diagnosing causes of urgency, frequency, incontinence, or dribbling.
Differentiates between overactive bladder, stress incontinence, and retention-related overflow incontinence. - Evaluates bladder function after surgeries, particularly abdominal, pelvic, or urological procedures.
Post-anesthesia urinary retention is common due to the temporary suppression of bladder reflexes. Bladder scanning ensures timely detection and intervention. - Ensures complete drainage in patients with urinary catheters.
Helps diagnose catheter-related problems, such as blockages or malpositioning, without requiring invasive procedures. - Used in patients with Parkinson’s disease, stroke, or diabetes to assess for neurogenic bladder dysfunction.
Identifies delayed bladder emptying, reducing the risk of renal complications from prolonged urinary retention.
Interfering Factors
Various external and patient-related conditions contribute to false readings or inaccurate bladder scanner readings.
- Obesity or excess abdominal tissue. Increased tissue thickness can interfere with ultrasound wave penetration, making it difficult to visualize the bladder clearly.
- Incorrect probe placement. Improper scanner positioning can prevent the bladder from being captured fully, resulting in inaccurate readings.
- Insufficient ultrasound gel. Inadequate gel reduces the conduction of ultrasound waves, resulting in poor image quality.
- Presence of excess bowel gas. The air within the bowel can obstruct sound waves, reducing image clarity and accuracy.
- Patient movement. Movement during scanning can disrupt probe stability, leading to incomplete or blurred images.
- Post-surgical scarring. Scar tissue may distort the bladder image, leading to incorrect volume measurements.
- Severe bladder deformities. Anatomical abnormalities like diverticula or tumors may alter the bladder shape and confuse scanner algorithms.
- Residual urine volume changes. Rapid changes in bladder volume (e.g., from recent voiding) can lead to discrepancies in measured versus actual volumes.
- Presence of an indwelling urethral catheter. A catheter can influence the bladder’s shape and cause discrepancies in volume measurements.
Who Performs Bladder Scanning?
Bladder scanning is typically performed by trained nurses or technicians who know the equipment and procedure. However, it can often be delegated to nursing assistive personnel (NAP) who have been properly trained and are competent in its use. Delegating depends on facility policies and the patient’s condition.
Equipment
Equipment needed.
- Bladder scanner
- Ultrasound gel
- Clean gloves
- Personal Protective Equipment (PPE) if indicated
- Disinfectant
- Paper towel or washcloth
- Documentation sheet
Steps on Assessing Bladder Volume Using a Bladder Scanner
To better understand bladder scanning, nurses can utilize the following steps.
1. Verify if a medical order is necessary per facility protocol, noting that some facilities permit nurses to use bladder scanners based on nursing judgment.
Reviewing the medical record and care plan identifies the correct patient and procedure.
2. Review the patient’s record for any physical activity limitations.
Physical limitations might necessitate adjustments to the technique.
3. Confirm the patient’s bladder is full and ask when the last void occurred for a pre-void measurement.
Knowing the time of the last void helps interpret bladder filling capacity and timing.
4. Instruct the patient to empty the bladder before the scan for a post-void residual volume measurement.
Helps identify issues such as incomplete bladder emptying or urinary retention.
5. Perform Handwashing before the procedure. Inform the patient about the steps involved.
Hand hygiene prevents the spread of infection. Explaining the procedure reduces anxiety and ensures cooperation
6. Position the patient lying supine with the lower abdomen exposed and the head slightly elevated for comfort. Adjust the bed to a convenient working height and lower the side rail on the working side if it is raised.
Positioning ensures patient comfort and proper access to the bladder area for scanning.
7. Select the appropriate sex setting on the scanner. If the patient is female and has had a hysterectomy, set the scanner to male.
Correct sex settings improve the scanner’s accuracy by calibrating it to the patient’s anatomy. Misdesignation can result in inaccurate bladder volume measurements.
6. Calibrate the bladder scanner, sanitize the scanner head with an alcohol pad or an appropriate cleanser, and allow it to dry completely.
Proper device use prevents errors, and cleaning the scanner head prevents cross-contamination between patients. Allowing it to air dry ensures the cleaning solution is fully effective.
8. Identify the symphysis pubis by palpation. Apply gel 2.5 to 4 cm above the symphysis pubis at the midline of the abdomen.
Locating the symphysis pubis ensures proper scanner alignment over the bladder. The gel facilitates sound wave transmission for clear imaging and accurate measurements.
9. Place the scanner head firmly on the gel, following the orientation instructions provided by the manufacturer. Hold it steady, apply light pressure, and angle it slightly downward toward the bladder. Press the scan button to begin.
Proper placement and steady pressure enhance the scanner’s ability to locate the bladder accurately. Pointing the scanner downward optimizes alignment for capturing the bladder’s image.
10. Record the bladder volume as displayed on the scanner.
Provides quantitative data to assess the need for intervention.
11. Document findings in the patient’s medical record and compare with patient symptoms and history.
Accurate interpretation helps guide clinical decisions and interventions.
12. Report significant deviations to the physician immediately.
Facilitates timely intervention to address potential complications.
13. Use a paper towel to wipe the gel off the patient’s abdomen.
Removing the gel keeps the patient comfortable and prevents residue from causing skin irritation.
14. Clean the scanner head with an alcohol wipe or cleanser, then allow it to dry before storing.
Proper cleaning after use prevents the transmission of infections and maintains equipment hygiene.
Bladder Scanning Results
The normal bladder volume before voiding typically ranges from 400-600 mL, indicating a full bladder. After voiding, the post-void residual (PVR) should be less than 50 mL in healthy adults, reflecting efficient bladder emptying. However, 50–100 mL may be acceptable in older adults due to decreased bladder elasticity.
| Result | Bladder volume | Clinical Significance | Nursing Actions |
|---|---|---|---|
| Normal Result | <50 mL (Post-Void Residual in Adults) | Indicates proper bladder emptying and normal urinary function. | Document findings, inform the patient of normal results, and monitor for new symptoms. |
| Borderline Result | 50-200 mL (Post-Void Residual) | Suggests incomplete bladder emptying; may indicate early urinary retention. | Reassess the patient, educate on potential causes, and notify the physician if persistent. |
| Abnormal Result | 200 mL (Post-Void Residual) | Indicates significant urinary retention, possibly due to obstruction, detrusor weakness, or neurological conditions. | Notify the physician, prepare for interventions (e.g., catheterization), and educate the patient. |
| Severely Abnormal | 400-500 mL (Bladder Volume without Voiding Attempt) | Indicates severe urinary retention or bladder overdistension, which can lead to complications like bladder rupture or kidney damage. | Provide immediate care, such as catheterization, closely monitor for complications, and document all actions. |
Nursing Considerations
By understanding the following points, nurses can ensure the effective and safe use of bladder scanning.
1. Verify the patient’s bladder fullness before scanning.
Assessing the patient’s last void or fluid intake ensures optimal bladder fullness for accurate results. Scanning an underfilled bladder may lead to false low-volume readings.
2. Ensure proper patient positioning.
Positioning the patient supine with the lower abdomen exposed provides the best access for scanning. Misalignment can result in incomplete visualization of the bladder.
3. Use a generous amount of ultrasound gel.
Applying enough gel minimizes air interference and ensures effective sound wave transmission for clear imaging. Insufficient gel can produce poor-quality images and unreliable results.
4. Set the gender correctly on the bladder scanner.
Selecting the appropriate gender (or male for females with a hysterectomy) calibrates the scanner for anatomical differences. Incorrect settings may lead to inaccurate bladder volume measurements.
5. Maintain proper scanner head orientation.
Aligning the scanner head according to manufacturer guidelines ensures optimal aim toward the bladder. Misalignment may cause false readings or missed data.
6. Interpret results in context.
Evaluate the bladder volume measurement in relation to the patient’s symptoms and medical condition. The results should guide but not solely dictate further interventions.
7. Monitor the patient with high residual volumes or urinary retention after the scan for signs of discomfort, urinary tract infection (UTI), or worsening retention.
Regularly reassess bladder volumes and report significant changes to the physician for timely intervention.
8. The use of a bladder scanner is contraindicated in pregnancy due to the presence of amniotic fluid, as well as in patients with ascites or open wounds in the suprapubic region.
Amniotic fluid and ascites can interfere with accurate bladder volume measurements by distorting the ultrasound signal. While open wounds in the suprapubic area increase the risk of infection and may cause discomfort during scanning.
Sources
- Kozier, B., (2018)- Canadian Fundamentals of Nursing 4th Canadian Edition
- Potter, P., (2017) – Fundamentals of Nursing 9th Edition
- Al-Shaikh, G., Larochelle, A., Campbell, C. E., Schachter, J., Baker, K., & Pascali, D. (2009). Accuracy of bladder scanning in the assessment of postvoid residual volume. Journal of obstetrics and gynaecology Canada, 31(6), 526-532.
- Ballstaedt, L., Leslie, S. W., & Woodbury, B. (2024). Bladder post void residual volume. In StatPearls [Internet]. StatPearls Publishing.
- Cho, M. K., Noh, E. J., & Kim, C. H. (2017). Accuracy and precision of a new portable ultrasound scanner, the Biocon-700, in residual urine volume measurement. International urogynecology journal, 28, 1057-1061.
- Ghani, K. R., Pilcher, J., Rowland, D., Patel, U., Nassiri, D., & Anson, K. (2008). Portable Ultrasonography and Bladder Volume Accuracy—A Comparative Study Using Three-Dimensional Ultrasonography. Urology, 72(1), 24–28.
- Gupta, S. S., Irukulla, P. K., Shenoy, M. A., Nyemba, V., Yacoub, D., & Kupfer, Y. (2017). Successful strategy to decrease indwelling catheter utilization rates in an academic medical intensive care unit. American Journal of Infection Control, 45(12), 1349–1355.
- Zhao, L., Liao, L., Gao, L., Gao, Y., Chen, G., Cong, H., … & Liao, X. (2019). Effects of bladder shape on accuracy of measurement of bladder volume using portable ultrasound scanner and development of correction method. Neurourology and Urodynamics, 38(2), 653-659.
- Zhu, X., Zou, L., Yao, Z., & Chen, Z. (2021). Abnormal deviation in the measurement of residual urine volume using a portable ultrasound bladder scanner: a case report. Translational Andrology and Urology, 10(7), 3084.