Ultrasound-Guided Cystocentesis: Precision for Veterinary Diagnostics

Why Ultrasound Is Now Standard for Cystocentesis

In our line of work, accuracy is one of the most crucial factors in ensuring a clean sample collection and an accurate diagnosis. When it comes to diagnostic procedures like cystocentesis, precision has a direct impact on patient outcomes, sample quality, and client satisfaction. That’s why ultrasound-guided cystocentesis is becoming the gold standard in veterinary practices everywhere.

Whether you're a seasoned practitioner or building a new hospital, integrating ultrasound guidance into routine procedures like cystocentesis can enhance the quality of care and improve diagnostic reliability.

It’s a win-win! But, before we get ahead of ourselves, let’s break it down…

What is Ultrasound-Guided Cystocentesis?

Cystocentesis is the percutaneous aspiration of urine from the bladder using a needle and syringe.

Traditionally, it’s performed by palpating (or feeling) the bladder manually, which can be effective in some cases, but not all.

Ultrasound-guided cystocentesis takes this a step further by using real-time imaging to guide the needle directly into the bladder, offering unmatched precision and reducing guesswork.

Why Use Ultrasound Guidance?

1. Increased Accuracy

One of the main advantages of ultrasound guidance is visual confirmation of bladder location, size, and wall integrity. This is especially helpful in:

• Obese patients where palpation is difficult

• Nervous or tense animals that guard their abdomen

• Patients with small or partially voided bladders

• Critical care patients who cannot be positioned ideally

By directly visualizing the bladder, we can ensure correct needle placement and avoid surrounding structures such as the intestines or uterus, significantly reducing the risk of complications.

2. Improved Sample Quality

When you’re aiming for a sterile urine sample for culture or cytology, contamination is a concern.

Palpation-based cystocentesis increases the risk of dry taps or puncturing non-target tissues, which can compromise the quality of the sample.

Ultrasound guidance minimizes these risks, resulting in cleaner samples, a higher diagnostic yield, and greater confidence in the results. This is particularly valuable when investigating things like:

• Urinary tract infections

• Hematuria

• Bladder masses

3. Greater Safety for Challenging Cases

In some instances, like patients with transitional cell carcinoma (TCC), cystoliths, or anatomical abnormalities, can be more safely evaluated with ultrasound guidance. You can:

• Avoid needle contact with neoplasms

• Visualize and avoid stones

• Confirm bladder fullness before attempting the procedure

This reduces the chance of iatrogenic injury (injuries caused by the needle) and aligns with best practices for minimally invasive care.

Now that we’ve got the basics covered, let’s unpack what good looks like for this particular procedure.

Tips and Best Practices for Ultrasound-Guided Cystocentesis

1. Use the Right Equipment

Invest in an ultrasound machine with high-resolution imaging and a microconvex or linear transducer; both are ideal for abdominal imaging in small animals. Having a veterinary-specific machine ensures preset parameters are optimized for soft tissue visualization.

Pro Tip: Use a hands-free probe holder or enlist a trained assistant to hold the transducer while you guide the needle. This helps maintain image stability and needle visibility.

2. Positioning Matters

Dorsal or lateral recumbency usually works best. Use gentle restraint to reduce stress and abdominal guarding. A calm, cooperative patient makes the procedure easier and more comfortable for everyone.

3. Visualize the Entire Path

Before inserting the needle, scan the full path from the skin surface to the bladder. This helps you identify any vessels, intestines, or abnormalities that could interfere with the procedure.

4. Use the In-Plane Technique (When Possible)

The “in-plane” approach is an ultrasound-guided technique in which the needle is inserted along the same plane as the ultrasound beam, allowing the entire length of the needle (including the tip) to be visible on the screen as it advances toward the target (in this case, the bladder).

Let’s look at it in action…

A 9-year-old spayed female Labrador retriever, Mila, presents with hematuria and pollakiuria, resulting in blood in her urine and frequent urges to urinate. On abdominal palpation, the bladder feels small and difficult to isolate. Rather than risk multiple blind attempts, her veterinarian uses ultrasound guidance. The bladder is visualized dorsal to the pubis, partially obscured by intestinal loops.

With the ultrasound probe held steady, a 22-gauge needle is guided in-plane, avoiding bowel loops and penetrating the bladder wall cleanly. A 7 mL urine sample is collected with no complication, and the diagnostic yield from both urinalysis and culture is high.

The client receives fast, accurate results, and the patient avoids the stress of repeat attempts or complications.

Is Your Practice Equipped for Precision?

Integrating ultrasound-guided techniques like this one isn’t just about upgrading your technology; it’s about upgrading your standard of care.

Not to mention, this is an excellent opportunity for veterinary technicians to enhance their clinical skill set while improving workflow efficiency within the practice.

With proper training, technicians can confidently perform this procedure, ensuring accurate sample collection and patient comfort.

By taking on this advanced task, technicians help free up the veterinarian’s time for more complex diagnostics, treatments, or client communication—ultimately enhancing the hospital’s overall productivity and quality of care.

Ultrasound-guided cystocentesis brings precision, safety, and diagnostic confidence to a routine veterinary procedure. As pet owners increasingly expect modern and accurate diagnostics, ultrasound is becoming the gold standard.