Extrahepatic biliary duct obstruction as a result of involuntary transcavitary implantation of hair in a cat

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

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.

Feline abdominal ultrasonography: what's normal? what's abnormal? The biliary tree

PRACTICAL RELEVANCE

Abdominal ultrasound plays a vital role in the diagnostic work-up of many cats presenting to general and specialist practitioners. The biliary tree encompasses the liver, gall bladder and bile ducts, although only diseases affecting the latter two are discussed here. Diseases of the bile ducts and gall bladder are more common than those of the liver parenchyma and ultrasound plays an important role in their diagnosis.

CLINICAL CHALLENGES

Despite ultrasonography being a commonly used modality, many practitioners are not comfortable performing an ultrasound examination or interpreting the resulting images. Even differentiating between normal variation and pathological changes can be challenging for all but the most experienced. In addition, a lack of pathological change does not necessarily rule out disease; for example, absence of gall bladder and/or extrahepatic biliary distension is not sufficient to exclude the possibility of biliary obstruction, and in many cases of cholangitis the liver and biliary tree are unremarkable on ultrasound examination.

EQUIPMENT

Ultrasound facilities are readily available to most practitioners, although use of ultrasonography as a diagnostic tool is highly dependent on operator experience.

AIM

This review, part of an occasional series on feline abdominal ultrasonography, discusses the appearance of the normal and diseased biliary system. It is aimed at general practitioners who wish to improve their knowledge and confidence in feline abdominal ultrasound and is accompanied by high-resolution images. Percutaneous ultrasound-guided cholecystocentesis is also covered. Ultrasound examination of the liver was discussed in an article published in January 2019 and an upcoming article will cover hepatic vascular anomalies.

EVIDENCE BASE

Information provided in this article is drawn from the published literature and the author's own clinical experience.