Congenital Abnormalities of Liver, Biliary, and Pancreas

Question 1

liver embryology

Answer 1

*liver appears during the 4th week of gestation as diverticulum arising from duodenum
*cranial portion forms parenchymal tissue + bile ducts
*caudal portion forms gallbladder + cystic duct

Question 2

bile canaliculi embryology

Answer 2

*bile canaliculi are well developed by 6 weeks of gestation
*intrahepatic ducts formed from cell plates derived from hepatic duct and is complete by 12 weeks of gestation
*gallbladder and cystic duct canalize by 8 weeks of gestation

Question 3

cholestasis

Answer 3

*decrease in bile flow due to:
1. impaired secretion by hepatocytes OR
2. obstruction of bile flow through intra- or extra-hepatic bile ducts
*elevation of serum CONJUGATED bilirubin (> 1.0)
*indicates hepatobiliary dysfunction
*affects approx 1/2500 infants

Question 4

neonatal cholestasis - ddx

Answer 4

*BILIARY ATRESIA (most common)
*neonatal hepatitis
*infectious hepatitis
*parenteral nutrition-associated liver disease

Question 5

neonatal cholestasis - staged evaluation

Answer 5

*clinical evaluation: history + PE
*initial labs: LFTs, fractionated bilirubin
*stool color assessment
*synthetic liver function: INR
*bacterial cultures (blood, urine)
*viral serology (TORCH, viral hepatitis, CMV, HIV)
*urine reducing substances
*alpha-1 antitrypsin phenotype
*thyroid function studies
*sweat test/CF gene
*newborn screen
*imaging (US, HIDA scan)
*liver biopsy

Question 6

biliary atresia - overview

Answer 6

*destructive inflammatory obliterative cholangiopathy
*intra- and extra-hepatic bile ducts are destroyed during neonatal period
*progressive fibrosis occurs rapidly

Question 7

biliary atresia - epidemiology

Answer 7

*most frequent identifiable cause of obstructive jaundice in the first 3 months of life
*most common indication for liver transplant in children
*1/10,000-20,000 incidence in US
*nonsyndromic (84%)
*syndromic:
-with laterality defect (10%) - situs inversus, malrotation, polysplenia, congenital heart disease
-without laterality defect (6%) - intestinal atresia, cardiac abnormalities

Question 8

biliary atresia - pathogenesis

Answer 8

*viral infection
*toxins
*genetic bile duct dysmorphogenesis
*chronic inflammatory or autoimmune mediated duct injury

**cholestasis identified soon after birth, suggesting biliary injury occurred BEFORE BIRTH

Question 9

biliary atresia - clinical features

Answer 9

*acholic stools (pale stools)
*growth failure
*dark urine
*hepatosplenomegaly (abdominal distention)
*jaundice
*direct/conjugated hyperbilirubinemia
*elevated LFTs (AST, ALT, GGT, alk phos)
*low fat-soluble vitamins (ADEK)

Question 10

biliary atresia - diagnostic steps

Answer 10

1. ultrasound - triangular cord sign, ABSENT/SMALL GALLBLADDER, no biliary ductal dilation
2. hepatobiliary scintigraphy (HIDA scan)
3. intraoperative cholangiogram (GOLD STANDARD) or liver biopsy (portal inflammation/fibrosis, bile duct proliferation and plugs)

Question 11

biliary atresia - importance of timely diagnosis

Answer 11

EXTREMELY IMPORTANT: time to treatment determines success of procedure (HPE or Kasai)
*no universal screening method

Question 12

biliary atresia - treatment

Answer 12

*Kasai hepatoportoenterostomy (HPE):
-excise extrahepatic biliary tree
-porta hepatis is transected at the liver capsule to expose remaining ductules
-jejunal Roux loop is anastomosed to cut surface

Question 13

biliary atresia - prognosis

Answer 13

*majority of patients will require liver transplantation
-primary failure of HPE
-progressive fibrosis -> cirrhosis
-growth failure
-portal HTN complications

*1 year and 5 year survival rates after transplant are really high!

Question 14

choledochal cysts

Answer 14

*cystic dilation of biliary tree
*incidence about 1 in 100,000
*30% diagnosed before age 1 year
*more common in females
*increased risk of cholangiocarcinoma
*dx = ultrasound
*treatment = surgical resection

Question 15

pancreas - embryology

Answer 15

*originates as dorsal bud and two ventral buds
*L ventral bud atrophies
*rotation of stomach & duodenum with elongation carries R ventral bud posteriorly
*fusion of R ventral with dorsal bud completes head & uncinate process

Question 16

annular pancreas - pathogenesis

Answer 16

*hypertrophy of normal pancreatic tissue
*fusion of heterotopic pancreatic rests
*failure of L ventral bud atrophy
*failure of free rotation of R ventral bud

Question 17

annular pancreas - clinical presentation

Answer 17

*sx may present at any age (2/3 asymptomatic; approx 50% present in pediatric age)
*vomiting
*peptic ulceration
*abdominal pain - pancreatitis
*jaundice - biliary obstruction
*associated with other congenital defects (Down’s syndrome, esophageal/duodenal atresia, imperforate anus, Meckel’s)

Question 18

annular pancreas - diagnosis

Answer 18

*evidence of duodenal obstruction on plain abdominal film (double bubble effect)
*barium studies demonstrating duodenal filling defect
*CT
*MRCP/ERCP
*laparotomy, if presents with obstruction

Question 19

annular pancreas - management

Answer 19

*surgical intervention in cases with obstruction
*recommended approach is a bypass operation
-duodenoduodenostomy is preferred

Question 20

pancreatic agenesis, hypoplasia, and dysplasia

Answer 20

*complete agenesis rare and usually incompatible with life
*clinical manifestations attributable to both exocrine and endocrine pancreatic dysfunction
*associated with other syndromes

Question 21

ectopic pancreas

Answer 21

*presence of pancreatic tissue lacking anatomic and vascular continuity with the main body of pancreas
*70-90% occurs in upper GI tract, mostly in gastric antrum
*usually incidental finding

Question 22

pancreatic divisum

Answer 22

*most common congenital pancreatic anomaly (10% of population)
*abnormality resulting from INCOMPLETE FUSION of dorsal and ventral pancreatic ductal systems
*dorsal duct functions as main drainage system but opens into smaller accessory papilla

Question 23

pancreatic divisum - clinical presentation

Answer 23

*majority are asymptomatic
*may cause recurrent attacks of pancreatitis or chronic epigastric pain (controversial)
*dx: MRCP/ERCP

Question 24

common channel syndrome (pancreatic duct anomaly)

Answer 24

*anomalous junctions of common bile duct and main pancreatic duct
*the presence of a long common channel with pancreaticobiliary junction located outside of duodenal wall associated with pancreatitis and choledochal cyst
*can lead to abdominal pain, pancreatitis
*dx and management with ERCP