Biliary drainage in perihilar cholangiocarcinoma: historical rationale and the evolving case for selective use.

INTRODUCTION: Cholestasis prevents optimal treatment of perihilar cholangiocarcinoma (pCCA). To counteract this, biliary drainage (BD) has long been regarded as mandatory prior to any treatment. However, increasing evidence has highlighted the risks associated with BD, notably cholangitis, indicating that while often necessary, drainage requires careful clinical judgment. AREAS COVERED: This narrative literature review outlines the historical development of BD and its rationales, including the restoration of liver function, a prerequisite for liver hypertrophy-inducing procedures, and improvement of performance status. The review also addresses its drawbacks, particularly the risk of cholangitis due to bacterial colonization of the biliary tree and summarizes the evidence shaping contemporary clinical practice. EXPERT OPINION: Once regarded as mandatory, BD can no longer be justified as a routine intervention for every pCCA patient, given the associated risks. Undrained partial hepatectomy should be considered in patients with moderate bilirubin levels, adequate future liver remnant volume, absence of cholangitis, normal performance status, and preserved liver and renal function. Still, this applies to only a minority of patients. Similarly, systemic therapy may be feasible without BD in highly selected patients. Future research should focus on defining selection criteria, investigating new biomarkers of cholestasis, and refining drainage techniques to minimize complications of BD.