Infants with cholestasis prior to 181 days of age present a challenging diagnostic problem of differentiation between an extra- and intra-hepatic location of the cholestatic process. This assessment is critical, since any evidence of obstruction essentially mandates surgical exploration. Extrahepatic biliary atresia (EHBA) is the most frequent cause of persistent unrelieved infant jaundice amenable to surgical correction.

This is a retrospective multi-center pathology project, which will examine interobserver variability in the histological diagnosis of infantile cholestasis with the aim of establishing reliable histological criteria of extra-hepatic obstruction in infants.

The evaluation of liver biopsies is a cornerstone in the work-up of the infant with cholestasis. The primary purpose of this project is to test interobserver variability in the histopathological assessment of liver biopsies taken from cholestatic infants < 181 days of age.

There are 3 major aims of this study: firstly, to determine the reliability and reproducibility of several pathologists to distinguish, on a liver biopsy, histological changes pointing to an extra-hepatic obstructive process. Secondly: to develop a set of criteria that could be reliably and confidently identified by pathologists with variable levels of expertise, practicing at different centers, to diagnose obstruction. And thirdly: To develop a standardized assessment of fibrosis on a liver biopsy of a child with biliary atresia for the purposes of prognostication.

There are no outcome measures for this study.

This is a retrospective study of infants <181 days with cholestasis for whom the pathologist at the institution can provide representative slides from their liver biopsy or biopsies. Therefore, the inclusion/exclusion criteria describe the biopsy, as well as the subject.

Inclusion Criteria:

• Patients who were infants at the time of biopsy, which was performed during the period between 01/01/2002 and 12/31/2002, and for which there was either a final clinical diagnosis available or imaging assessment that determined the presence or absence of an obstruction will be considered for this study.

Exclusion Criteria:

• Patients for whom there is an inability to provide two representative slides from the liver biopsy will not be included in this study.