Ultrasonographic Features of Extrahepatic Biliary Obstruction in 30 Cats

Abstract

The goals of our study were to review the ultrasonographic features of spontaneous extrahepatic biliary obstruction in cats and to determine whether these features can assist in differentiating tumor, inflammation, and choleliths as the cause of obstruction. Thirty cats with a presurgical ultrasound examination an dconfirmed extrahepatic biliary obstruction were studied. A common bile duct diameter over 5 mm was present in 97% of the cats with extrahepatic biliary obstruction. Gallbladder dilation was seen in < 50% of the cats. Ultrasound identified all obstructive choleliths (calculus or plugs) in the common bile duct. However, neither common bile duct diameter nor appearance or any other ultrasonographic feature allowed differentiation between tumor and inflammation as the cause of obstruction. A short duration of clinical signs (10 days or less) seemed to be associated with obstructive cholelithiasis.

Extrahepatic biliary tract obstruction in two ferrets (Mustela putorius furo)

“…Choleliths in dogs and cats are predominantly of calcium carbonate composition (Gaillot and others 2007); however, in the present ferret cases the distal biliary tract obstruction was caused by fragile plugs containing only protein and bilirubin crystals.…”

Liver and biliary tract

“…When studying a cohort of cats with spontaneous EHBTO, ultrasound detected a CBD > 5 mm in 97% of cats but only 50% of cats had a dilated gallbladder. 15 Polyps, neoplastic masses such as adenomas or adenocarcinomas, or cysts within the gallbladder, cystic or CBD can be imaged via ultrasound although cystic hyperplasia with diffuse irregular wall thickening is more common.…”

Liver

“…15 In a separate study, 97% of obstructed cats had a common bile duct diameter greater than 5 mm, and 90% had dilated extrahepatic or intrahepatic ducts. 201 However, lower percentages of common bile duct dilation have been reported in cats. 247,248 The caudate and right lateral liver lobes provide the best acoustic window to the common duct region, which otherwise may be obscured by gas in the stomach or bowel.…”

“…198 Dogs or cats with cholelithiasis may have clinical signs of vomiting, anorexia, weakness, polyuria and polydipsia, weight loss, icterus, fever, and abdominal pain. 201 Differential diagnosis of shadowing lesions within the liver must include fibrosis, to F, and 9-44, B and C). 175,199,200 The stones shift to the dependent portion of the gallbladder when the animal is repositioned (see Figure 9-43).…”

“…Bile duct Figure 9-45, B). 201 Therefore it seems possible that intrahepatic duct dilation, along with common duct enlargement, may be the only signs of extrahepatic biliary obstruction seen in some cats, because the gallbladder and extrahepatic ducts are not always enlarged (Figure 9-55; see also . 201 Therefore it seems possible that intrahepatic duct dilation, along with common duct enlargement, may be the only signs of extrahepatic biliary obstruction seen in some cats, because the gallbladder and extrahepatic ducts are not always enlarged (Figure 9-55; see also .…”