An ultrasound of the urinary bladder can be recommended for a number of reasons, including suspected uroliths, cystitis, and neoplasia—to name a few.
Often, the evaluation includes the entire abdomen and any other parts of the urinary tract that can be visualized.
Given all the conditions that can affect the bladder, as well as important information from an ultrasound study to help guide the treatment plan, it’s beneficial to gain proficiency in evaluating the bladder via ultrasound.
Use a Systemic Approach to Evaluating the Bladder
A systemic approach to the whole abdomen is good, and a bladder evaluation is usually just one part of an abdominal ultrasound study. So while it may be tempting to jump to the bladder right away if the patient is having urinary symptoms, it’s best to complete your abdominal ultrasound study in the same order that you usually do it.
Once you reach the urinary bladder, a systemic approach is again useful, to ensure nothing is missed. Here is one method for a stepwise evaluation…
Is the overall bladder shape normal and as expected? Through practice, a veterinarian can get a good feel for what shape is normal for canine and feline patients, and how it may change if the bladder is full versus empty or nearly empty.
How does the lumen of the bladder look? If urine is present, is the urine is anechoic? Is there sludge, sediment, crystalline material, a polyp, or anything else that is abnormal?
If there are uroliths present, they generally appear as hyperechoic structures inside the lumen of the bladder. There may be acoustic shadowing, and the calculi may move freely depending on how large they are.
Is the bladder wall smooth, a normal thickness, and well-defined? Be sure to evaluate the entire bladder. If cystitis is present the wall may be focally or generally thickened or have irregularities in the mucosa, depending on the severity and duration of the cystitis. Keep an eye out for polyps or masses/tumors, too. Also, look for deviations in the wall that could indicate a urinary bladder diverticulum.
If a mass is present, make note of the size, appearance, and location. Transitional cell carcinoma, the most common neoplasia of the bladder, tends to occur in the bladder wall near the neck and trigone. Commonly, these masses are hyperechoic or mixed echoic and have been compared to cauliflower in appearance. Evaluate nearby blood vessels and regional lymph nodes, too. Avoid cystocentesis or aspiration for samples, because of the risk of seeding the neoplasia into the abdominal cavity when the needle is withdrawn. Sometimes, it’s easy to confuse blood clots with masses, so keep this in mind and re-evaluate as needed.
Be sure to evaluate other urogenital structures, including the kidneys and ureters (the latter are often not visible unless there’s an abnormality), as well as blood vessels and lymph nodes in the region. Remember to look for the uterus/ovaries in intact females and the prostate in males, although it might not be possible to visualize these structures in all patients, especially if they are normal.
Whenever abnormalities are noticed, describe them in detail and take measurements. Include all of this in the notes. Even if things look normal, it’s still a good idea to take some measurements (such as bladder wall thickness) and describe what you’re seeing, as a baseline for comparison in case anything changes in the future.
A Few Tips
A full bladder can help with visualizing certain lesions (such as hyperechoic uroliths) by providing “contrast” or a backdrop to help make abnormalities stand out. Also, a full bladder smooths out the bladder wall, whereas an empty bladder may lead to false readings of wall thickening or masses. Additionally, a large bladder allows for an easier ultrasound-guided cystocentesis. So whenever possible, try to ultrasound with a full, or at least partly full, bladder. In some cases, it may be appropriate to give the patient water or IV/SQ fluids and wait for the bladder to fill prior to the study.
Pressure from the transducer can alter the bladder’s shape.
So be sure to practice with various pressures and become familiar with how the appearance of the bladder might change.
Repositioning the patient can also be helpful.
This may give you a better viewing angle and position for certain structures. Having the patient stand up may put gravity in your favor by decreasing the distance between the bladder and the probe. Also, patient movement may cause sludge/sediment to move around or disperse so that it’s not mistaken for a urolith.
Have appropriately sized needles, syringes, and collection materials available.
In case an aspiration/cystocentesis is needed, it’s best to have supplies ready to go.
Ultrasound of the urinary bladder is a very valuable skill, and it works well in conjunction with information gained from x-ray studies. Training and practice in ultrasound of the urinary bladder are often well worth it for patient care and for additional income from ultrasound studies.
Written by: Dr. Tammy Powell, DVM
