Ultrasound Assessment of the Gallbladder Wall: An Important Marker in the Acute Setting

Stephanie Lisciandro, DVM, DACVIM (SAIM)

Point-of-care ultrasound (Global FAST®) is an important extension of the physical examination in acutely ill veterinary patients. When combined with laboratory testing, it can help clinicians reach a timely diagnosis and begin appropriate treatment.

Ultrasound evaluation of the gallbladder is particularly valuable. Gallbladder wall edema (GBWE), also known as the “gallbladder halo sign,” may be associated with:

• Anaphylaxis
• Right-sided heart failure
• Pericardial effusion
• Acute cholecystitis
• Hypoproteinemia
• Immune-mediated anemia
• Sepsis
• Pancreatitis
• Post-transfusion reactions

This discussion focuses on GBWE associated with cardiac disease, as described in the 2021 Journal of Veterinary Internal Medicine article, “Thirteen dogs and a cat with ultrasonographically detected gallbladder wall edema associated with cardiac disease” (Lisciandro GR, et al.).

Recognizing the cause of GBWE is especially important in emergency patients because anaphylaxis and cardiac disease may present similarly, including acute weakness and collapse.

GBWE appears ultrasonographically as a thickened, layered gallbladder wall measuring approximately 3–5 mm. Its striated white-black-white or white-gray-white appearance creates the characteristic “gallbladder halo sign.”

In our peer-reviewed case series:

• 11 of 13 dogs had pericardial effusion
• One dog had dilated cardiomyopathy
• One dog had right ventricular myocardial failure
• Nine dogs also had ascites
• One cat had ascites and right-sided heart failure associated with a ventricular septal defect

Patients with ascites are often referred for abdominal ultrasound, but significant thoracic disease may be missed—especially when no heart murmur or other obvious cardiac abnormality is present.

When evaluating the liver and gallbladder, use adequate depth at the AFAST®-TFAST® Diaphragmatico-Hepatic (DH) View to look beyond the diaphragm and into the thorax. Pericardial effusion may appear as an anechoic rim surrounding the heart, known as the “Racetrack Sign.” The caudal vena cava (CVC) and hepatic veins should also be evaluated for distention.

The appearance of the CVC can help distinguish between anaphylactic and cardiac causes of GBWE:

• Anaphylactic gallbladder: The CVC is often small or collapsed (“flat”) because severe hypovolemic-distributive shock reduces venous return.
• Cardiac gallbladder: The CVC is often distended (“FAT”) with little or no “bounce,” supporting venous congestion caused by right-sided heart failure or impaired cardiac filling from pericardial effusion.

Global FAST® combines AFAST®, TFAST®, and Vet BLUE® into a standardized point-of-care examination. This approach helps clinicians evaluate the gallbladder, heart, lungs, CVC, and hepatic veins so they can more accurately distinguish cardiac disease from anaphylaxis and other causes of GBWE.

Ultrasound is valuable in emergency patients and should be considered an extension of the physical examination in every sick animal. Visit FASTVet.com or subscribe to our emails for additional resources on incorporating ultrasound into everyday veterinary practice.

References:

1. Lisciandro GR, Gambino JM, Lisciandro SC. Thirteen dogs and a cat with ultrasonographically detected gallbladder wall edema associated with cardiac disease. J Vet Intern Med 2021;35: 1342–1346. https://doi.org/10.1111/jvim.16117.
2. Chou Y, Ward JL, Baron LZ, Murphy SD, Topf MA, Lisciandro GR, et al. Focused ultrasound of the caudal vena cava in dogs with cavitary effusions or congestive heart failure: a prospective observational study. PLoS One 2021;16(5):e0252544. doi:10.1371/journal.pone.0252544.
3. Lisciandro GR. Abdominal and thoracic focused assessment with sonography for trauma, triage and monitoring in small animals. J Vet Emerg Crit Care 2011;21(2):104-122.
4. Lisciandro GR. The use of the diaphragmatico-hepatic (DH) views of the abdominal and thoracic focused assessment with sonography for triage (AFAST/TFAST) examinations for the detection of pericardial effusion in 24 dogs (2011-2012).  J Vet Emerg Crit Care 2016; 26(1):125-31.
5. Nelson NC, Drost WT, Lerche P, et al. Noninvasive estimation of central venous pressure in anesthetized dogs by measurement of hepatic venous blood flow velocity and abdominal venous diameter. Vet Radiol Ultrasound 2010;51(3):313-323.