True about Extrahepatic binary atresia –
Extrahepatic binary atresia 

Biliary Atresia is the absence of patent bile duct draning the liver.
The abnormality found most commonly is complete atresia of extrahepatic biliary structures.
Infants with biliary atresia often has an uneventful neonatal course until jaundice is noted at 2-3 weeks of age.
Conjugated hyperbilirubinemia occurs.
Urine is dark in colour
Stools may be normal or clay coloured (acholic).
The liver may be of normal size early, but it becomes enlarged with time.
Liver becomes hard as a consequence of progressive cirrhosis
Splenomegally is usually seen

Laboratory findings

Direct bilirubin levels over 3 mg/dl
Alkaline phosphatase elevated to 500-1000 units/L
Gamma Glutamyl transpeptidase levels > 300 units/L

Imaging studies

Absence or inability to visualize a contracted gall bladder on USG
Serial Scintiscans of right upper abdomen should be obtained after injection of Technitium Tc 99m. labeled iminodiacetate. Compounds (IDA, HIDA, PIPIDA) --> Liver fails to secret these compounds into the duodenum due to biliary obstruction.
Needle biopsy of the liver - If bleeding and clotting tests are normal.
Acholic stool
Conjugated hyperbilirubinemia
Absence of nucleide in duodenum in HIDA scan
All of these