Biliary Atresia and Choledochal Cysts Overview

Study Notes

Biliary Atresia

Most common type of obstructive biliary disease in infants and young children.
Absence or destruction of extrahepatic bile ducts (common hepatic duct and common bile duct).
Twice as common in males.
Suspected when jaundice (hyperbilirubinemia) persists beyond 14 days of age.
Up to 38% of children can survive with their own liver for 30 years after a Kasai portoenterostomy (KPE) procedure.
Associated with a "Triangular Cord Sign": an echogenic, triangular structure anterior to the portal vein.
KPE is the most successful treatment if performed before 90 days of life.
Liver transplantation is also considered.
Associated with polysplenia, absent inferior vena cava, situs inversus, situs ambiguous, and cardiac anomalies (atrial septal defect, ventricular septal defect).

Choledochal Cysts

Congenital bile duct anomaly, involving cystic dilation of extrahepatic bile ducts.
Most common type (Type I) involves dilatation of the common bile duct.
More prevalent in Asia, with over 33% of reported cases originating from Japan.
Symptoms usually occur before age 10.
Sonographic findings (Type I): two cystic structures in the right upper quadrant (gallbladder and dilated common bile duct), and intrahepatic bile duct dilatation.
Associated with pancreatitis, cholangitis, cirrhosis, portal hypertension, and cholangiocarcinoma.

Caroli Disease/Caroli Syndrome

Congenital anomaly of the biliary tract.
Multifocal segmental dilatation of intrahepatic bile ducts.
Generally inherited, associated with congenital hepatic fibrosis, autosomal recessive polycystic kidney disease, and portal hypertension.
Sonographic findings: multiple cystic structures converging toward the porta hepatis, communicating with bile ducts, and sludge and calculi may accumulate in these ectatic ducts.

Courvoisier Gallbladder

Occurs with a distal mass.
Dilation begins with the gallbladder, followed by the common duct, and finally the intrahepatic tree.
After removal of the obstructing mass, the gallbladder decompresses actively, and the ducts passively return to normal in reverse order.

Hydropic Gallbladder

Overdistended gallbladder filled with mucoid, thick bile, or pus.
Most common cause is a stone obstructing the gallbladder neck or cystic duct.
Usually non-inflammatory.
Can be asymptomatic, or associated with right upper quadrant pain, nausea, vomiting, and a palpable mass.
Can be associated with Kawasaki disease.
Sonographic findings: grossly distended, thin-walled, measuring greater than 5 cm transversely (width) and greater than 4 cm anteroposteriorly. May have stones.

Causes of a Non-visualized Gallbladder

Patient is non-fasting.
Post-cholecystectomy.
Contracted gallbladder with stones (chronic cholecystitis).
Congenitally absent gallbladder.
Porcelain gallbladder.
Hepatization of the gallbladder.
Mirizzi syndrome or gallstone ileus.
Gallbladder neoplasms completely filling the lumen.
Ectopic gallbladder.
Emphysematous gallbladder.
Overlying bowel.
Residual barium in nearby bowel.

Post-Cholecystectomy

The diameter of the common duct increases with age.
The 1 millimeter per decade rule is an acceptable rate of size increase.
Age 60, duct measuring 6 mm is normal.
Age 80, duct measuring 8 mm is normal.
After surgical removal, there is controversy over the size increase of the common duct.
The most accepted theory is that the common duct acts as a reservoir for bile storage, measuring up to 10 mm.

Fatty Meal

Administering a fatty meal can assess biliary dynamics, gallbladder contractility, and obstruction.
Cholecystokinin, a hormone released into the blood by ingestion of fatty foods, causes gallbladder contraction.
Equivocal bile duct dilatation or abnormal lab values (conjugated bilirubin, alkaline phosphatase) are reasons to administer a fatty meal.
Negative results: unchanged or decreased size.
Positive results: duct increase in size.

Biliary Obstruction

Obstruction causing direct interference with bile flow.
Can be intrinsic or extrinsic (stones, tumors, or strictures).
Intrahepatic or extrahepatic.
Majority are due to pathology in the distal common bile duct.
Gallstones and carcinoma of the head of the pancreas are the two most common lesions.

Elevated Labs

Alkaline phosphatase, direct bilirubin, gamma-glutamyl transferase.

Clinically

Jaundice, right upper quadrant pain, fever, palpable right upper quadrant mass.

Causes of Biliary Obstruction

Choledocholithiasis, Mirizzi syndrome, cholangitis, biliary atresia, choledochal cyst, Caroli disease, pancreatic adenocarcinoma, and gallbladder carcinoma.

Dilated Intrahepatic Ducts

Criteria to differentiate intrahepatic bile ducts from portal veins: "parallel channel sign" and "double barreled shotgun sign".
Dilated hepatic duct anterior to the portal vein.
Intrahepatic ducts greater than 2 mm or more than 40% of the portal vein are considered dilated.

Causes of Intrahepatic Bile Duct Dilatation Only

Cholangiocarcinoma (Klatskin tumor).
Intrahepatic choledocholithiasis.
Recurrent pyogenic cholangitis.
Caroli's disease.

Description

Explore the critical concepts surrounding biliary atresia and choledochal cysts. This quiz covers diagnosis, treatment efficacy, and associated anomalies related to these conditions. Understand the implications for infants and young children, including surgical interventions and long-term outcomes.