A stent graft (10) for placement in a lumen of a patient comprises a main body (20) comprising a main lumen (22) and having a distal end terminating in a bifurcation. It also comprises first and second legs (100, 200) extending from the bifurcation, the first and second legs having respective first and second leg lumens (105, 205) in fluid communication with the main lumen (22) and a side arm (300) extending from the first leg, the side arm having a side arm lumen (305). The side arm lumen (305) is in fluid communication with the first leg lumen (105) at a position adjacent to the bifurcation. A combined lumen is formed. The combined lumen is between the main lumen (22) and a distal portion of the first leg lumen (105) and is bounded laterally by a portion of the side arm located adjacent to the bifurcation.
