Although bilateral endoscopic drainage is regarded as essential for achieving adequate liver volume drainage in unresectable high-grade malignant hilar biliary obstruction (MHO), limited evidence exists regarding the comparative outcomes of bilateral versus tri-segmental drainage. We aimed to evaluate and compare the clinical outcomes of bilateral and tri-segmental biliary drainage in patients with unresectable MHO.

After propensity score matching, 52 patients with unresectable MHO of Bismuth type IIIa or IV were included. Patients underwent plastic stent placement for drainage of either two hepatic sectors (bilateral group; left plus right anterior or right posterior, n = 26) or all three hepatic sectors (tri-segmental group, n = 26). The primary outcome was clinical success, and secondary outcomes were procedure time, adverse events (AEs), and time to recurrent biliary obstruction (RBO).

The clinical success rate was 76.9% (20/26) in the bilateral group and 84.6% (22/26) in the tri-segmental group (P = 0.727). The tri-segmental group demonstrated a significantly longer median time to RBO (44 days vs. 67 days, P = 0.003), whereas the procedure time was significantly shorter in the bilateral group (28.2 ± 8.3 minutes vs. 35.6 ± 11.3 minutes, P = 0.017). Overal AE rates were comparable between the two groups, and no severe AEs were observed (3.8% vs. 7.7%, P = 1.000).

Our findings suggest that, without undue concern for procedure-related AEs from prolonged duration, attempting to drain all technically feasible hepatic sectors could confer clinical benefit in the management of unresectable high-grade MHO.