A bladder ultrasound is a non-invasive imaging technique that uses high-frequency sound waves to create real-time pictures of the bladder. This procedure helps medical professionals visualize the bladder’s structure and function without discomfort or radiation exposure. It is a common tool for assessing overall bladder health and identifying various issues that might affect its ability to store and release urine.
Why a Bladder Ultrasound is Performed
Doctors order a bladder ultrasound to investigate various symptoms related to urinary health. This imaging technique is helpful for adults and children experiencing issues such as frequent urination, difficulty starting or maintaining a urine stream, or the presence of blood in the urine, known as hematuria.
The ultrasound can help determine the cause of recurrent urinary tract infections (UTIs) or assess how well the bladder empties. It is also used to evaluate conditions like urinary incontinence, where there is involuntary leakage of urine, or urinary retention, which is the inability to fully empty the bladder. A bladder ultrasound can identify the presence of bladder stones, tumors, or other structural abnormalities within the bladder.
Common Bladder Ultrasound Measurements
During a bladder ultrasound, several specific measurements are taken to provide a detailed assessment of bladder function. One primary measurement is bladder volume, which indicates how much urine the bladder holds. This is often measured twice: once when the bladder is full (pre-void volume) and again immediately after the patient has urinated (post-void volume).
The post-void residual (PVR) volume is significant, representing the amount of urine remaining in the bladder after urination. This measurement helps determine if the bladder is emptying completely or if there is any urine retention. Bladder wall thickness is another important measurement, which is assessed when the bladder is adequately filled. This measurement helps evaluate the condition of the bladder muscle.
To estimate bladder volume, ultrasound machines use a formula such as Length × Width × Height × 0.7, or a correction coefficient based on the bladder’s shape. The thickness of the bladder wall is measured on the anterior wall when the bladder is more than 50% full.
Interpreting Bladder Ultrasound Results
Interpreting bladder ultrasound results involves comparing the measurements to established normal ranges and identifying any visual abnormalities. For post-void residual (PVR) volume, a normal finding in adults is less than 50 milliliters (mL). An elevated PVR volume suggests issues such as a bladder outlet obstruction, which prevents urine from flowing out freely, or problems with the nerves that control bladder function.
Bladder wall thickness also provides important diagnostic information. In adults, a bladder wall measurement greater than 7 millimeters when the bladder is full can indicate a pathological condition. Thickening of the bladder wall suggests chronic inflammation, an overactive bladder, or an obstruction at the bladder outlet. Conversely, a very thin bladder wall is associated with conditions like detrusor underactivity, where the bladder muscle does not contract effectively.
Beyond these specific measurements, the ultrasound can reveal other findings. It can detect the presence of bladder stones, which appear as bright, reflective objects, or identify diverticula, which are small pouches that bulge outwards from the bladder wall. The ultrasound can visualize suspicious masses or tumors within the bladder for diagnosis and further medical evaluation.
Preparing for a Bladder Ultrasound
Preparing for a bladder ultrasound involves a few simple steps to ensure clear images are obtained. Patients are instructed to have a full bladder for the examination. This means drinking a certain amount of water, such as one liter (approximately 32 ounces), about 30 minutes to an hour before the scheduled appointment.
It is important not to urinate before the test, as the sonographer needs to assess the bladder when it is distended. Patients should wear comfortable, loose-fitting clothing to allow easy access to the lower abdomen. Any prescribed medications should be taken as usual unless otherwise directed by a doctor. Arriving a few minutes early allows for check-in and any last-minute preparations.