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119.e2 Biliary System (Extrahepatic): Surgical Disorders

Biliary System (Extrahepatic): Surgical Disorders Client Education
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collecting or divisional ducts draining the
BASIC INFORMATION
ferential ≥ 20 mg/dL (>1.1 mmol/L) is
right, left, and central divisions of the liver. ○ Ascites to peripheral blood glucose dif-
Definition • The cystic duct may join the right or left consistent with septic peritonitis.
Surgical disorders of the extrahepatic biliary central divisional duct to form the CBD. ○ Ascites to peripheral blood total bilirubin
system (EHBS) can be divided into diseases • The CBD enters the duodenum at the major differential ≥ 2x is consistent with bile
that affect 1) the gallbladder (GB) and cystic duodenal papilla. In the cat, the CBD fuses peritonitis.
duct, 2) the common bile duct (CBD) and with the pancreatic duct before entering the
hepatic ducts, or 3) the duodenal papilla. duodenum at the major duodenal papilla. Advanced or Confirmatory Testing
Diseases of the CBD can be subdivided into In the dog, the CBD and pancreatic duct • Abdominal radiographs have limited value
mural, extramural, and intraluminal types. both enter the duodenum at the major for the diagnosis of the diseases of the EHBS.
Surgical conditions of the EHBS include duodenal papilla without uniting. In both ○ Radiopaque choleliths (containing calcium
obstructive cholelithiasis, bile duct obstruction species, the accessory pancreatic duct enters bilirubinate) may be visualized.
from other causes, necrotizing cholecystitis, GB the duodenum at the minor duodenal papilla. ○ Gas in the EHBS indicates an emphyse-
mucocele, and cholangiocellular (bile duct) • The accessory pancreatic duct is present in matous process.
tumors. Pancreatitis and duodenal foreign only 20% of cats. ○ Decreased abdominal serosal detail may
bodies can result in obstruction of the CBD be seen with pancreatitis or peritonitis.
and duodenal papilla, respectively, and may DIAGNOSIS ○ Helps to rule out other disorders
warrant surgical intervention. Bile peritonitis • Ultrasound provides excellent visualization
for any cause warrants surgical intervention. Diagnostic Overview of the EHBS and is a valuable diagnostic
Neoplasia of the GB is rare but has been Extrahepatic biliary disease should be on the tool when the findings are correlated with
reported. differential diagnosis list for any patient with serum biochemistry results.
evidence of cranial abdominal pain, icterus, or • Ultrasound findings can include
Epidemiology elevated serum hepatic enzyme activities and/ ○ Ascites
SPECIES, AGE, SEX or total bilirubin concentration. ○ Cholelithiasis
Dogs and cats, any age, either sex (signalment ○ Hepatic duct or CBD distention: the
varies by cause) Differential Diagnosis normal CBD is ≤ 6 mm wide in the dog
• Proximal duodenal disorders, including and ≤ 5 mm wide in the cat.
GENETICS, BREED PREDISPOSITION luminal foreign bodies and inflammatory ■ Distention of the CBD may not be
Shetland sheepdogs, border terriers, cocker disorders of the duodenal wall visualized for 5-7 days after obstruction.
spaniels, and miniature schnauzers are predis- • Pancreatitis ■ Distended intrahepatic bile ducts can
posed to GB mucocele. Miniature schnauzers • Intrahepatic parenchymal disorders be visualized 5-7 days after obstruction.
are predisposed to pancreatitis and secondary • Causes of icterus (p. 1243) These appear as non-uniform diameter
CBD obstruction. with irregular branching patterns
Initial Database (unlike blood vessels).
RISK FACTORS • CBC results vary, depending on the cause, ○ GB wall thickening (GB wall thickness
Risk factors are cause dependent (see specific severity, and suddenness of onset of the in healthy dogs is 2-3 mm; in cats ≤
disease processes). biliary obstruction. 1 mm)
• Increased serum liver enzyme activities and ○ Highly reliable for GB rupture (86%
Clinical Presentation bilirubin concentration are common. sensitive) and GB mucocele
DISEASE FORMS/SUBTYPES • Hypoglycemia is possible with sepsis or septic ○ The value of GB ultrasound to determine
Patients may show overt clinical signs or may peritonitis. the potential for bacterial cholecystitis has
have subclinical disease. Factors that affect the • Coagulation profile and thromboelastogra- recently been described.
presence or absence of clinical manifestations phy: chronic EHBO may result in one of ○ A normal GB ultrasound has a negative
include the degree of obstruction of the CBD two types of hemostatic disorders. predictive value for positive bacterial
and the integrity of the GB. ○ Coagulopathy caused by vitamin K culture of 96% for cats and 88% for dogs.
deficiency–associated reductions in activi-
HISTORY, CHIEF COMPLAINT ties of coagulation factors II, VII, IX, and TREATMENT
Generally nonspecific, with lethargy and X (altered enterohepatic circulation of
gastrointestinal (GI) signs predominating vitamin K) Treatment Overview
○ Hypercoagulability has been documented Surgical management is cause specific. Potential
PHYSICAL EXAM FINDINGS with thromboelastography in dogs with for sepsis and coagulopathy secondary to EHBO
• Icterus is usually present with extrahepatic EHBO. must be considered before surgery, and
biliary obstruction (EHBO), but lack of • Presence of ascites warrants abdominal intraoperative blood pressure monitoring is
icterus does not rule out partial EHBO. paracentesis for fluid analysis (cytology, essential.
• Nonspecific findings may include tachycardia, glucose, and total bilirubin analysis).
tachypnea, fever, dehydration, cranial ○ Nucleated cell count ≥ 13,000 cells/mcL Acute and Chronic Treatment
abdominal pain, and abdominal effusion. is 86% sensitive for septic effusion; • Cholecystotomy: indications are rare but
specificity may be reduced by nonseptic include
Etiology and Pathophysiology disorders (e.g., uroabdomen, bile perito- ○ Removal of GB choleliths that are not
• Anatomically, a single GB and cystic duct nitis) but from a practical standpoint, the resulting in significant GB inflammation
is the norm in dogs and cats (although a disorders associated with such cell counts ○ Histopathologic analysis and bacterial
bilobed GB is not uncommon in cats). The justify exploratory surgery, with or without culture of the GB wall (contraindicated
CBD is formed from three or four major evidence of a septic process. in acute or necrotizing cholecystitis)

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