Biliary atresia is a rare, progressive liver disease that only affects infants. It leads to complete obstruction and scarring of the bile duct. Current non-invasive diagnostic tests have limited sensitivity.

Indocyanine Green (ICG) is a non-radioactive, fluorescent compound with several clinical applications including angiography for ophthalmologic testing, visualization during surgery, and measurement of liver function. After excitation with near infrared light (750-810 nm), ICG emits near infrared light at 850 nm, which can be detected by a special camera. ICG is taken up by the liver exclusively and excreted in the bile, where it is removed from the body in the stool. The hypothesis is that after injection of ICG, participants with biliary atresia will not have any fluorescence detected in the stool. Investigators aim to use ICG as a functional test of bile duct patency in participants with cholestasis being evaluated for biliary atresia.

Inclusion Criteria:

1. age <3 months viable infants
2. cholestasis (defined as direct bilirubin >1)
3. undergoing diagnostic HIDA scan to evaluate for biliary atresia

Exclusion Criteria

1. kidney disease (eGFR <60 mL/min/1.73m2)
2. grossly bloody stools
3. history of bowel surgery or disease
4. history of allergic reaction to ICG, iodine, or shellfish
5. unable to provide informed consent