Overall survival, clinical significance and biochemical composition of 'white bile' in patients with impaired biliary drainage: a systematic review.

White bile (WB) is a colourless and transparent watery fluid sometimes observed in the biliary system. The clinical significance and underlying mechanisms of this condition remain unclear. This systematic review evaluated overall survival (OS) between patients with WB and coloured bile (CB) and malignant biliary obstruction and described all available evidence regarding the prevalence, aetiology and composition of WB. We conducted a systematic search on PubMed, Scopus and Web of Science using the terms “white”, “translucent” and “clear bile” (February 28th, 2025). Data were independently screened and synthesized using a predefined data template considering the studies objectives and results. Overall survival was considered the main outcome. The quality of the studies was assessed using the Joanna Briggs Institute standardized critical appraisal tool. From 473 initial records, 31 studies with 302 patients with WB were included (5 cohort studies, 1 case-control study and 25 case reports or case series). Six studies investigated the prognostic significance of WB: three found association between WB and longer OS, one found association only in the non-operable group and two did not find it. The prevalence of WB varied from 2.9% to 53.4% and resulted from both malignant and benign conditions impairing biliary drainage. Bile levels of bilirubin, bile salts and cholesterol were practically absent in WB and serum bilirubin was higher when compared WB with CB. The association of WB with worse survival in patients with malignant biliary obstruction could not be established with the current evidence. To clarify its prognostic significance, further well-designed studies are needed.