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Determining the Volume of Residual Urine by Ultrasonography
Essentials
- Any doctor or nurse can determine the volume of residual urine after brief education (video Residual Urine Volume (Ultrasonography)).
- Ultrasound devices that only focus on determining the volume of residual urine are also available on the market. They are able to perform the measurement accurately enough, but a regular ultrasonic device provides significantly more information, which is why using the latter is recommended.
- Ultrasonography is the method of choice for determining residual urine volume, because urinary tract infections resulting from bladder catheterization can be avoided Reliability and Effectiveness of Real-Time Ultrasonic Bladder Volume Estimation.
Indications
- Urinary incontinence (to rule out overflow)
- Urinary symptoms in elderly men
- Urinary tract infection in the male
- A palpable mass in the lower abdomen
- Urinary retention (obstruction to urinary outflow or anuria?)
- Increased serum creatinine (to rule out obstruction)
- Ensuring that the bladder is sufficiently empty before removing a percutaneous cystostomy.
- The tube is kept closed for at least 4 hours, and the residual urine is measured after the patient has voided urine the natural way. The residual urine volume should be under 200 ml.
Techniques
- The patient voids.
- Keep the ultrasonography probe in a transverse position and find a view that shows the bladder in its maximum size. Freeze the view and measure the horizontal (a) and vertical (b) dimensions of the bladder.
- Move the probe to a longitudinal position, find the maximum longitudinal dimension (c) of the bladder and measure it.
- The (minimum estimate of) residual urine volume = 0.6 × width × height × length. If the dimensions are given in cm, the result is in ml. See pictures and .
- A volume exceeding 100 ml is abnormal, a volume exceeding 200 ml is usually an indication of pharmacological treatment in male patients, and a volume exceeding 500 ml even in long-term retention is an indication for percutaneous cystostomy or catheterization.
- The volume of the prostate http://www.dynamed.com/condition/benign-prostatic-hyperplasia-bph#PROSTATE_ULTRASOUND can be measured by using the same formula (videos Prostatic Volume Estimation (Ultrasonography) and Very Large Prostate, pictures ).
Examining the full bladder