QUARTERLY BEAT
JULY 2026
Liver Cytologic sampling of the liver is reasonable in any patient with elevated liver values and/or gross ultrasonographic changes of disease. For patients with diffuse disease, typically the left medial and left lateral lobes are sampled to avoid iatrogenic puncture of the gallbladder, bile duct, and great vessels entering the porta hepatis. Either a subcostal or left intercostal approach may be performed, but care should be taken not to pass through the pleural space or accidentally puncture the diaphragm, lung, or adjacent gastrointestinal tract.
As expected, surgically obtained biopsies are much more accurate than ultrasound-guided needle biopsies.
Gallbladder Cholecystocentesis was once thought too high risk for routine use due to the concern of biliary leakage or rupture causing bile peritonitis. Over the past 25 years, numerous studies have validated this technique as a safe procedure with valuable diagnostic yield. Similar to other techniques, minor complications can occur and involve transient and clinically insignificant peritoneal effusion that is likely hemorrhage or a small volume of bile (Byfield 2017 and Peters 2016). The incidence of bile septic peritonitis is fortunately very low, ranging between 0 – 3.7% among 3 large studies involving over 500 dogs and cats total (Byfield 2017, Schiborra 2017, and Smith 2016). Other reported major complications associated with the procedure include systemic inflammatory response syndrome, hypotensive shock, acute kidney injury, and cardiopulmonary arrest (Schiborra 2017). However, given the presumed severity of illness of some patients with hepatic disease, these complications are likely a reflection of the patient’s overall stability or disease progression rather than the safety of the procedure alone.
Ultrasound image of the liver with a hypoechoic triangular wedge of free abdominal effusion. Photo courtesy of Dr. Amy Kaplan-Zattler, cVMA, DACVECC, MRCVS.
Unfortunately, needle samples from the liver are some of the least accurate as compared to other abdominal organs with a diagnostic accuracy of 60% or lower depending on the condition. Cytology is a reasonable screening tool for hepatic lipidosis, vacuolar hepatopathy, and neoplasia but poor for inflammatory, mineral storage, and fibrotic diseases, as well as necrosis and hyperplasia (Bahr 2013, Cohen 2003, Roth 2001, and Wang 2004). In cases where poorly exfoliative disease is suspected, choosing a surgical biopsy may save both time and money to achieve a definitive diagnosis. Curiously, FNA may be more accurate than needle biopsy when sampling the liver and kidney to diagnosis feline infectious peritonitis (Giordano 2005). The diagnostic yield
Ultrasound image of the gallbladder. Photo courtesy of Dr. Amy Kaplan- Zattler, cVMA, DACVECC, MRCVS .
Cholecystocentesis should be considered in dogs and cats where sterile or infectious cholecystitis/cholangiohepatitis is suspected because ultrasound findings alone have poor accuracy (62%) for predicting a positive bile culture (Schiborra 2017 and Smith 2017). Collected bile may be submitted for cytology and culture. Patients should be heavily sedated or anesthetized to prevent complications related to patient movement. As discussed in Part 1, the author prefers to connect a 22G, 1.5-inch needle to an extension set with a three-way stop cock and syringe. This allows the needle to be held steadily in place without movement induced from aspiration, which can be challenging if the bile sample is thick. Patients may be placed in ventral or left lateral recumbency so the needle may be inserted via a subcostal or intercostal approach. Evidence is not clear as to which is safest: inserting the needle directly into the gallbladder or passing through a small portion of liver, termed “transhepatic.” The former prevents cross contamination of the
of the liver was higher than the kidney and sensitivity may improve when both FNA and needle biopsy are evaluated.
Overall, cytology cannot be relied on to rule out disease due to an overall poor sensitivity for most etiologies. In the author’s institution, hepatic FN-NA is routinely performed and most accurate for round cell neoplasia, diffuse infiltrative infectious disease,
fatty change, and nodular regeneration. If aspirate results do not match the patient’s clinical picture, are non-diagnostic, or the
patient is not responding to therapy, then biopsy should be performed.
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VETGIRL BEAT EMAGAZINE 27
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