From the Guidelines
A bladder scan and bladder ultrasound are essentially the same procedure, both using ultrasound technology to visualize the bladder, while post-void residual (PVR) volume is a measurement obtained through these tests. A bladder scan/ultrasound is a non-invasive procedure that uses sound waves to create images of the bladder and measure urine volume. When performed after urination, this measurement is called the post-void residual volume, which indicates how much urine remains in the bladder after voiding.
Key Differences and Uses
- Bladder scans are typically performed by nurses at the bedside using portable devices, while formal bladder ultrasounds are conducted by ultrasound technicians using more sophisticated equipment that can provide detailed images of the bladder and surrounding structures.
- You would use a bladder scan for quick assessment of urinary retention, monitoring PVR in patients with voiding difficulties, or evaluating bladder function.
- PVR measurement is specifically used to assess bladder emptying efficiency and is important in diagnosing conditions like urinary retention, neurogenic bladder, or bladder outlet obstruction, as recommended by the AUA/SUFU guideline on adult neurogenic lower urinary tract dysfunction: diagnosis and evaluation 1.
- A formal bladder ultrasound would be used when more detailed imaging is needed to evaluate bladder wall thickness, detect masses, stones, or anatomical abnormalities, or to investigate complex urological conditions.
Post-Void Residual Volume
- Normal PVR is generally less than 50-100 ml; values above this may indicate incomplete bladder emptying requiring further evaluation or intervention.
- The AUA/SUFU guideline suggests that a post-void residual measurement should be performed at the time of diagnosis and may be checked periodically thereafter to monitor for changes in bladder emptying ability, regardless of symptoms 1.
- Clinicians may perform PVR in patients with LUTS as a safety measure to rule out significant urinary retention both initially and during follow-up, as stated in the urodynamic studies in adults: AUA/SUFU guideline 1.
From the Research
Overview of Bladder Scan, Residual Volume, and Bladder Ultrasound
- A bladder scan, also known as a bladder ultrasound, is a non-invasive test used to measure the amount of urine left in the bladder after urination, known as the post-void residual (PVR) volume 2, 3, 4.
- The PVR volume is an important measure to assess urinary retention and bladder function 2, 5.
- A bladder ultrasound is a type of imaging test that uses high-frequency sound waves to produce images of the bladder and measure its volume 4, 6.
Difference Between Bladder Scan, Residual Volume, and Bladder Ultrasound
- A bladder scan and a bladder ultrasound are often used interchangeably to refer to the same test, which measures the PVR volume 2, 4.
- The PVR volume is the amount of urine left in the bladder after urination, which can be measured using a bladder scan, bladder ultrasound, or catheterization 2, 3, 5.
- The main difference between a bladder scan and a bladder ultrasound is the technology used, with a bladder scan being a more specialized device for measuring bladder volume 3, 6.
When to Use Each Test
- A bladder scan or bladder ultrasound is commonly used to measure PVR volume in patients with urinary retention, bladder dysfunction, or pelvic organ prolapse 2, 5.
- Catheterization is considered the gold standard for measuring PVR volume, but it is an invasive procedure and may not be necessary in all cases 2, 4.
- A bladder scan or bladder ultrasound can be used as an alternative to catheterization for measuring PVR volume, especially in patients who are at risk of urinary tract infections or have difficulty with catheterization 4, 6.
- The choice of test depends on the patient's medical history, the availability of equipment, and the clinical judgment of the healthcare provider 6.