Methods, devices and systems are described for treating venous insufficiency in which the vein is compressed at least partially along a treatment zone. A system can be provided including an injection device (300), such as a glue gun, that is operably connected to a delivery catheter (202) that can be advanced across a treatment zone in the vein (400). The delivery catheter can be used to deliver one, two, or more boluses of media (V2, V2') (e.g., cyanoacrylate) to occlude the vein (400) along different spaced-apart sections of the treatment zone. External compression can also be applied to the vein (400) by a compression element, such as a hand (640) or multifunctional ultrasound transducer (630), to occlude portions of the vein (400) along the treatment zone prior to or during the introduction of the boluses of media (V2. V2').