{"id":47663,"date":"2020-05-24T23:00:00","date_gmt":"2020-05-24T23:00:00","guid":{"rendered":"https:\/\/www.imv-imaging.com\/2020\/05\/the-liver-part-3-the-gall-bladder\/"},"modified":"2026-02-27T16:31:20","modified_gmt":"2026-02-27T16:31:20","slug":"news-the-liver-part-3-the-gall-bladder","status":"publish","type":"post","link":"https:\/\/www.imv-imaging.com\/en\/2020\/05\/news-the-liver-part-3-the-gall-bladder\/","title":{"rendered":"The Liver part 3: The Gall Bladder"},"content":{"rendered":"\n

Following on from the previous articles examining ultrasonography of the liver parenchyma and associated pathological conditions, this article will focus on the gall bladder and biliary system.<\/p>\n\n\n\n

Examination of the gall bladder and biliary system should be included as part of the routine ultrasonographic study of the liver and surrounding cranial abdominal anatomy. The indications for examination of the gall bladder and patient preparation are the same as those described for the liver.<\/p>\n\n\n\n

Normal anatomy and ultrasonographic appearance<\/h4>\n\n\n\n

The gall bladder is situated in a fossa between the quadrate and right medial lobes of the liver. It acts as a reservoir for bile and appears as an anechoic round\/oval to teardrop shaped structure situated just to the right of midline in most patients. The gall bladder can be bilobed in some cats.<\/p>\n\n\n\n

Gallbladder size<\/h5>\n\n\n\n

The size of the gall bladder is variable and will alter depending on when the animal was fed. Post-prandially enzymes are released which cause the gall bladder to contract. The volume of the gall bladder is increased in anorexic or fasted patients.<\/p>\n\n\n\n

In the normal gall bladder, the wall appears as a smooth and thin hyperechoic line (Figure 1). Wall thickness is less than 1mm in cats and 2-3mm in dogs1<\/sup>.<\/p>\n\n\n\n

\"Normal<\/figure>\n\n\n\n

Figure 1. This transverse plane image shows the normal gall bladder (GB) in a dog. Note the acoustic enhancement (*) making the liver parenchyma deep to the gall bladder appear more echoic.<\/em><\/p>\n\n\n\n

The intrahepatic biliary tree is not visible in normal patients. Biliary canaliculi merge to form the interlobar and lobar ducts which eventually form the hepatic ducts which join the cystic duct from the gall bladder, thereby becoming the common bile duct (Figure 2). In normal dogs, the common bile duct can be difficult to visualise, while in cats it is often more visible in normal patients.<\/p>\n\n\n\n

The normal common bile duct is less than 3mm diameter in dogs and less than 4mm diameter in cats2<\/sup>. In dogs, the common bile duct joins the duodenum at the major duodenal papilla, separately from the pancreatic duct. An accessory pancreatic duct joins the duodenum at the minor papilla in most dogs though anatomic variation exists. In cats, the common bile duct fuses with the pancreatic duct before entering the major papilla. Only 20% of cats are estimated to have an accessory pancreatic duct3 <\/sup>(Figure 3).<\/p>\n\n\n\n

\"gall<\/figure>\n\n\n\n

Figure 2. A schematic representation of the anatomy of the biliary system and surrounding structures.<\/em><\/p>\n\n\n\n

\"biliary<\/figure>\n\n\n\n

Figure 3. A schematic representation of the pancreatic ducts and biliary system in dogs and cats. PD = Pancreatic Duct, AP= Accessory Pancreatic Duct.<\/em><\/p>\n\n\n\n

Biliary sludge is seen routinely within the gallbladder lumen of asymptomatic dogs. Sludge appears as hyperechoic, non-shadowing sediment and is usually mobile. This causes sludge to alter location based patient position and it will collect on the dependant aspect of the gall bladder as a result of gravity (Figure 4). The presence of biliary sludge may indicate delayed gall bladder emptying4<\/sup> and in cats has been found to be predictive of increased liver enzymes5<\/sup>.<\/p>\n\n\n\n

\"biliary<\/figure>\n\n\n\n

Figure 4. Gall bladder sludge (sediment) \u2013 The image on the left shows hyperechoic sediment within the lumen of the gall bladder (red arrow). The right image shows a layer of sludge within the gall bladder lumen (S) with more mineralised material adjacent to the caudal wall of the gall bladder (red arrowhead). Note the acoustic shadowing distal to the mineralised material (*).<\/em><\/p>\n\n\n\n

Gall Bladder Wall Thickening<\/h3>\n\n\n\n

Thickening of the gall bladder wall can be caused by several different conditions (Figure 5):<\/p>\n\n\n\n