What to Expect From a Bladder Ultrasound (2024)

A bladder ultrasound is a noninvasive imaging technique used to check for abnormalities in the urinary bladder. It involves the use of a handheld device called a transducer that bounces high-frequency sound waves off the bladder to create detailed images without exposure to radiation or the need for anesthesia.

A bladder ultrasound can provide valuable information about the cause of functional disorders like overactive bladder and detect abnormalities like bladder stones or bladder cancer.

Reasons for Ordering a Bladder Ultrasound

Common reasons why a bladder ultrasound may be ordered include:

• Abnormally low urine output (oliguria)
• Bladder leakage (urinary incontinence)
• Blood in urine (hematuria)
• Difficulty starting or maintaining a urine stream (urinary hesitancy)
• Inability to fully empty the bladder (urinary retention)
• Pain with urination (dysuria)
• Recurrent urinary tract infections (UTIs)
  
• Sudden urge to pee frequently (urinary frequency)
  

The urinary bladder is a hollow muscular organ that serves as a reservoir for urine (pee). The adult bladder holds between 400 and 500 milliliters (mL) of urine and, when full, has a symmetrical shape with smooth walls 2 to 3 millimeters (mm) thick.

Located within the walls is a smooth (involuntary) muscle called the detrusor muscle, which contracts when needed to squeeze urine out of the bladder.

If you have urinary problems, the bladder is one of the first organs examined with ultrasound. Theureters(the tubes that transfer urine from thekidneysto the bladder) and the bladder neck (the connection between the bladder and a tube called theurethrathrough which urine exits the body) are also examined.

What a Bladder Ultrasound Can Detect

A bladder ultrasound, also known as a bladder sonogram or bladder sonography, is used to assess three major things: the anatomy of your bladder (including the thickness of the bladder wall), how much urine your bladder can hold, and how much urine is left after you pee.

The procedure is often done while your bladder is full. This provides an unobstructed view of the organ, shifting other organs like the uterus and bowel out of the way. A full bladder helps do the same during pregnancy so that the bladder is not overshadowed by the uterus and fetus.

Ultrasonography can also help calculate the amount of urine left in the bladder after urination, referred to as post-void residual (PVR) volume. In this case, it is performed after urinating.

An ultrasound can help diagnose many diseases and disorders affecting the bladder, including:

• Overactive bladder (OAB): A common condition characterized by the need to urinate frequently and urgently, including at night
• Bladder stones: Hardened mineral deposits that form when your urine becomes overly concentrated
• Bladder outlet obstruction (BOO): Blockage of the bladder neck by stones and tumors as well as enlarged prostate, prolapsed uterus, scarring, and genetic deformity of the bladder neck
• Bladder diverticula: Abnormal pouches that form in the bladder wall, sometimes congenital (something you are born with) or caused by extreme pressure induced by bladder obstruction
• Acute cystitis: Also known as a bladder infection, more commonly seen in females than males
• Interstitial cystitis (IC): A condition of unknown origin, also known as painful bladder syndrome, that causes inflammation of the bladder wall
• Ureterocele: A congenital condition in which the lower end of the ureter bulges, reducing the amount of urine that enters the bladder
  
• Bladder cancer: Most commonly transitional cell carcinoma (TCC) and less commonly squamous cell carcinoma, adenocarcinoma, and sarcoma

Types of Bladder Ultrasound

While all ultrasounds operate on the same principle, some devices are designed for specific body organs and have specific uses.

The general-purpose ultrasound is composed of a handheld transducer that simultaneously sends and receives sound waves emitted in units known as megahertz (MHz). The received signals are translated by computer into images for display on a digital monitor.

Standard abdominal ultrasounds used for deep organs emit lower frequency sound waves (1 to 6MHz), while those used for superficial tissues like skin, muscles, and breasts emit sound waves up to 100 MHz.

There are 2D ultrasounds that generate flat, cross-sectional images and three-dimensional (3D) ultrasounds that composite images from different angles to generate a 3D image. The latter is better able to calculate PVR volume than its two-dimensional counterpart.

There are also Doppler ultrasounds that incorporate two separate transducers—one to emit and another to receive sound waves—to measure blood flow in addition to standard imaging. An enhanced version, called a color Doppler ultrasound, translates the speed of blood flow into different colors. Both are useful in detecting vascular abnormalities like blood clots.

The Ultrasound Prep Process

The same basic procedure is used for all external ultrasound scans. The imaging can be done by a urologist in their medical office or at a special imaging facility by a trained technician. If the imaging is done while you are being treated at a hospital, it is referred to as a point-of-care ultrasound (POCUS).

In addition to the ultrasound device, the procedure involves a clear gel that allows the sound waves to pass in and out of your body without dispersing into the air.

During the procedure, the technician will view the monitor and capture images of your bladder for review by a specialist.

The basic steps for a bladder ultrasound, also called a bladder scan, are as follows:

1. You need to drink four 8-ounce glasses of water (32 ounces) one hour before the scan. If you can't hold it and need to pee, drink more water to compensate and advise the technician.
2. You may need to undress or remove the clothing from your torso.
3. You will be placed on your back on the examination table. Your abdomen will be exposed, and a sheet will be draped over your groin and legs.
4. The transducer gel will be applied to your abdomen and spread around with the transducer.
5. The technician will scan your abdomen in different directions, with tilting and rotating as needed.
6. If requested, you may be asked to empty your bladder and return for another set of scans to calculate the PVR volume. Most bladder ultrasound machines today can automatically calculate the pre- and post-void volume.
7. After the scan is complete, the excess gel is wiped away. You will then wait until the technician confirms all the requested scans are clear,

Once you are cleared to leave, you can change back into your clothes and return to work or home on your own.

Normal Bladder vs. Abnormal Scan Results

If performed by your urologist, a bladder scan can often be interpreted while you are there. If done in an imaging facility, the images will usually be reviewed by a radiologist who will interpret the images and write a report for your healthcare provider.

Depending on the aims of the evaluation, the bladder scan can assess:

• Bladder wall anatomy (including thickness and texture)
• Anatomy of the bladder neck and ureters
• Bladder capacity in milliliters
  
• Post-void residual volume in milliliters
  

Together and on their own, the findings can provide valuable information as to the underlying cause of urologic problems like:

• Bladder cancer: Ultrasounds can sometimes suggest which type of cancer is involved based on its location. TCC typically arises from the lining of the bladder, while sarcoma arises from the muscle layer. A color Doppler can differentiate a blood clot from a tumor. The accuracy varies by the tumor type.
• Bladder diverticuli: These abnormal pouches are usually easily seen on an ultrasound. Your urologist will also want to know their effect on your ability to empty the bladder. Ultrasound is also valuable for planning diverticular surgery.
• Bladder emptying: A PVR volume of less than 50 mL is considered adequate, while older adults may be normal at 50 to 100 mL. On the other hand, a PVR volume over 200 mL is considered abnormal and may be due to incomplete bladder emptying or bladder outlet obstruction.
• Bladder outlet obstruction: Blockages are often easy to spot on ultrasound, either by the internal blockage of the bladder neck by a stone, tumor, or scar tissues or by external compression of the bladder neck by an enlarged prostate or other protrusions.
• Bladder stones: These stones appear as highly reflective masses on ultrasound, casting shadows and moving about as your posture is shifted. This differentiates bladder stones from bladder tumors, which don't move.
• Cystitis: With acute cystitis, an ultrasound often reveals an irregular inner wall lining with evidence of debris in your urine.
• Overactive bladder: With OAB, ultrasound is often used to check for PVR.
• Ureteroceles: These defects are more common in females than males, usually affecting only one rather than both ureters. On ultrasound, a ureterocele is usually easily spotted as a bulging, fluid-filled mass, much like a cyst.

Next Steps With Abnormal Ultrasound

Oftentimes, an abnormal result on an ultrasound is not diagnostic of any particular medical condition, and further testing will be needed to confirm the cause. This is especially true of functional disorders like OAB which can be caused by many different things.

To make a definitive diagnosis, your urologist may order additional tests, including:

• Biopsy: The extraction of a sample of bladder tissue, often performed during cystoscopy, to check for cancer cells or other abnormalities
• Computed tomography (CT): An imaging study that composites multiple X-rays to generate three-dimensional images of organs
• Cystoscopy: A procedure involving the insertion of a narrow scope into your urethra to view the inside of your bladder
• Intravenous pyelography (IVP): An X-ray-based test that uses an injected dye to highlight urologic abnormalities like tumors or obstructions
• Magnetic resonance imaging (MRI): An imaging technique that uses powerful magnetic and radio waves to generate highly detailed images of soft tissues
• Urinalysis: The lab evaluation of a urine sample to detect abnormalities like bleeding or excessive white blood cells (a sign of infection)
• Urine culture: A lab test used to detect the presence of bacteria or fungi in your urine
• Urodynamic testing: A test, commonly involving a urinary catheter or ultrasound, that evaluates the function of the bladder based on volume and speed of urination
  

Summary

A bladder ultrasound is a safe, noninvasive tool that creates images of the bladder using high-frequency sound waves. It is performed while your bladder is full to check the thickness of the bladder wall, see how much urine it holds, and calculate how much urine remains after you pee.

A bladder ultrasound can identify problems like bladder stones, diverticula, tumors, and obstructions and help diagnose conditions like overactive bladder, interstitial cystitis, and bladder cancer.