Gastro - jaundice Flashcards
How many infants become visible jaundiced?
50%
More prevalent in pre-term babies
What is the pathogenesis of infant unconjugated jaundice? Due to haemolysis?
Increased lysis of RBCs: Enzyme defects (G6PD, pyruvate kinase) Structural (spherocytosis) Isoimmunisation (blood group incompability eg. ABO, Rh) Infection Shortened lifespan of RBC (70 days) Sequestered blood (cephalohematoma, bruising, intracranial haemorrhage) Polycythaemia
What is the pathogenesis of infant conjugated jaundice? (hepatocellular)
Hepatitis (neonatal idiopathic, viral, bacterial (e.coli, UTI))
Total parenteral nutrition
Hepatic ischaemia
Metabolic disorders (alpha1-antitrypsin def., galactosemia, tyrosinaemia, glycogen storage disorders, CF)
What is the pathogenesis of infant unconjugated jaundice? Due to decreased hepatic uptake?
Immature glucuronyl transferase activity in all newborns.
Breastmilk jaundice - inhibits glucuronyl transferase activity.
Gilbert syndrome
Pyloric stenosis
Hypothyroidism
Crigler-Najjar syndrome (NO glucuronyl transferase - very rare)
How can increased enterohepatic reabsorption (includes bilirubin) cause unconjugated jaundice?
Breast feeding - dehydration if inadequate milk supply
Bowel obstruction
No enteric feedings
Which biliary tree conditions lead to conjugated jaundice?
Biliary tree atresia (unconjugated at first, later conjugated after 2 weeks)
Choledochal cyst
Bile Plug syndrome
Why is jaundice within the first 24 hours of life worrying?
It indicates haemolysis and thus unconjugated bilirubin
which can lead to kernicterus
Which signs distinguish conjugated from unconjugated bilirubinaemia?
Dark urine and unpigmented STOOLS suggests conjugated bilirubinaemia. Assessing stools is thus very important
Hepatomegaly and poor weight gain may be other features.
What is biliary atresia?
Progressive disease in which there is destruction or absence of the extrahepatic biliary tree and the intrahepatic biliary ducts.
What are the presenting features of biliary atresia? (history, exam)
Normal birth weight but fail to thrive.
Dark urine, pale stools.
Mild jaundice.
Often hepatomegaly and there may be splenomegaly secondary to portal HTN.
Jaundice at >2 weeks (persistent)
What investigation results point towards biliary atresia?
LFTs of little differential value.
There may be contracted or absent gallbladder on fasting US.
Radioisotope scan with TIBIDA shows good uptake into liver, but no excretion into bowel.
Liver biopsy may show extrahepatic biliary obstruction.
Diagnosis confirmed at laparotomy by operative cholangiography which fails to outline a normal biliary tree.
What is physiological jaundice?
Jaundice at 2 days to 2 weeks, after considering other causes
What are the presenting features of viral hepatitis in children?
Nausea Vomiting Abdo pain Lethargy Jaundice (50-70%)
Large tender liver and splenomegaly (30%)
AST/ALT high
Coagulation usually normal
How is Hep A transmitted and how does it present?
Faecal-oral transmission
May be asymptomatic, or mild illness with recovery in 2-4 weeks
Some develop prolonged cholestatic hepatitis (self-limiting)
How is HBV transmitted?
Perinatal from mother Transfusion Needlestick injury Renal dialysis Horizontally in family
What is the significance of perinatal HBV? Diagnosis?
90% of infants become chronic carriers, and 30-50% develop chronic HBV liver disease. Cirrhosis in 10%.
5-10% of older children become carriers.
Thus, should be prevented by maternal screening and giving the infant a course of hep B vaccine if indicated
Diagnosed by IgM antibody to virus (acute) or HBsAG (ongoing infection)
How does Hep C cause disease in infants? Impact?
Transfusions and vertical spread, especially if co-infection with HIV.
Majority become chronic carriers. (20-50% lifetime risk of cirrhosis/HCC)
High prevalence in IVDU
How does Hep D cause disease in children?
It occurs as a co-infection with Hep B or a superinfection causing acute exacerbation of chronic Hep B
Cirrhosis in 50-70% of chronic HDV
What are the presenting features of Non-A to G hepatitis
Similar to Hep A (asymptomatic or mild illness - acute)
Apart from the Hep viruses, which other virus can cause hepatitis in children?
EBV
usually asymptomatic.
40% have hepatitis that may become fulminant
Which viral infections can cause acute liver failure in children?
Hep A, B, C
Non-A to G
In which infants should serum bilirubin be measured? (NICE)
Jaundice at <24 hours (measure within 2 hours!!) Then every 6 until below threshhold and stable.
Gestation <35 weeks
Otherwise, first line is transcutaneous bilirubinometer.
If it shows >250micromol/L, check with serum levels.
Which investigations are required to assess the underlying cause of jaundice in infants? (NICE)
Serum bilirubin (for baseline to assess response to treatment) Blood packed cell volume Blood group (mother and baby)
Direct Coomb’s test (DAT): did mother have anti-D immunoglobulin?
Which investigations are useful in assessing the underlying cause of jaundice in infants? (NICE)
FBC and blood film
Blood G6PD levels (take into account ethnic origin)
Microbiological cultures of blood, urine, CSF (if infection suspected)
