Gallbladder sludge in cats: common finding, poor predictor of biliary infection

Gallbladder sludge in cats: associations with bile culture, liver enzymes and cholangiohepatitis in 166 cases

King Long Hannah Lee; Sarah C Guess; Nicolas F Villarino; Jillian M Haines; Yoko M Ambrosini

Background

Gallbladder sludge (GBS) is a frequent ultrasonographic finding in cats and has historically been suspected to indicate biliary infection or inflammatory hepatobiliary disease, including neutrophilic cholangitis/cholangiohepatitis (NC/CH). Prior studies have produced conflicting results regarding its diagnostic relevance, and GBS is often interpreted alongside concurrent findings such as pancreatitis or small intestinal thickening. This study aimed to clarify the clinical significance of GBS by evaluating its associations with bile culture results, cytology, liver enzyme abnormalities, bilirubin concentration, and ultrasonographic evidence of concurrent disease in cats undergoing percutaneous ultrasound-guided cholecystocentesis (PUC).

Methods

A retrospective review was conducted of 166 cats that underwent PUC at a single academic institution between June 2015 and August 2024. Inclusion required a complete abdominal ultrasound performed within 24 hours prior to bile sampling. Data collected included ultrasonographic presence of GBS, bile culture and cytology results, serum alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin, and diagnoses of NC/CH. Associations between GBS and clinicopathologic, microbiologic, and ultrasonographic variables were assessed using Fisher’s exact test and odds ratios.

Results

Gallbladder sludge was identified in 64% of cats. There was no significant association between GBS and positive bile culture, bactibilia, or a diagnosis of NC/CH. GBS was also not associated with elevations in ALP or total bilirubin. Cats with GBS were more likely to have normal ALT activity compared with cats without GBS. Among GBS-positive cats, concurrent ultrasonographic findings of pancreatitis or small intestinal thickening did not significantly increase the likelihood of NC/CH. In contrast, gallbladder wall thickening, regardless of GBS status, was strongly associated with NC/CH. Enterococcus species and Escherichia coli were the most commonly isolated organisms from positive bile cultures.

Limitations

The study’s retrospective design introduced inherent limitations, including incomplete medical records, variability in diagnostic testing, and potential selection bias, as cats undergoing PUC were likely pre-selected based on clinical suspicion. Bile volume submitted for culture was not standardized, prior antimicrobial use was inconsistently documented, and histopathology was not available for confirmation of diagnoses. The diagnostic accuracy of liver cytology and ultrasonographic criteria may have further influenced case classification.

Conclusions

Gallbladder sludge is a common ultrasonographic finding in cats but does not reliably predict biliary infection, neutrophilic cholangitis/cholangiohepatitis, or clinically relevant biochemical abnormalities. The presence of concurrent pancreatitis or intestinal thickening does not enhance its diagnostic value. These findings indicate that GBS should not be used in isolation to justify antimicrobial therapy or bile sampling, and that clinical decision-making should instead rely on the broader clinical and diagnostic context.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.