Common bile duct obstruction caused by a helminth in a cat in the UK: ultrasonographic findings, histopathology and outcome

Abstract

Case summary: An 11-year-old neutered female domestic shorthair cat presented to our hospital with a 5-day history of vomiting, lethargy, anorexia and hyperbilirubinaemia, despite intravenous fluid therapy, gastroprotectants and antibiotic treatment. An abdominal ultrasound revealed a markedly distended common bile duct (diameter 6.2 mm). The cystic duct and intrahepatic bile ducts were also dilated. A linear structure formed by two parallel hyperechoic lines was identified in the common bile duct and could be traced to the duodenal papilla. The cat underwent laparotomy for surgical decompression of the biliary tree. A tubular, brown-coloured structure was retrieved from the common bile duct. Histological examination was consistent with a degenerate helminth. The cat recovered uneventfully from the surgery and its demeanour and appetite improved rapidly over the following days. Liver and gallbladder wall histopathology was consistent with bacterial cholangitis and cholecystitis. Escherichia coli was cultured from both bile and liver parenchyma.

Relevance and novel information: To our knowledge, this is the first reported case of extrahepatic biliary duct obstruction caused by a helminth in a cat in the UK. We hypothesised that the obstruction had been caused by the aberrant migration of an intestinal nematode that became lodged in the duodenal papilla. Ultrasound allowed prompt diagnosis and guided the treatment decision.

Keywords: Common bile duct; cholestasis; helminth; liver; ultrasound.

Figure 1

Ultrasonographic image of the distended gallbladder with anaechoic content. The gallbladder wall appears thickened and irregular

Figure 2

Ultrasonographic image of the common bile duct in long axis. The duct is dilated with a maximum diameter of 6.2 mm

Figure 3

Dilated common bile duct in long axis. In the lumen a linear structure delimitated by two parallel hyperechoic lines is visible in this ultrasound image

Figure 4

Transverse ultrasound image of the distended common bile duct and intraluminal linear structure

Figure 5

Tubular structure retrieved from the common bile duct

Figure 6

Histopathology image of the degenerated helminth retrieved surgically from the common bile duct. (a) Digestive tract; (b) reproductive tract (haematoxylin and eosin, ×100, scale bar=250 µm)

Figure 7

Histopathology image of the degenerated helminth retrieved from the common bile duct. Several eggs are visible. Some of the eggs contain eosinophilic globular material, which suggests these eggs were embryonated (haematoxylin and eosin, ×150, scale bar=250 µm)