Systems, methods and kits relating to in-situ forming polymer foams for the treatment of aneurysms are disclosed. The systems include an insertable medical device and an in-situ forming foam that is formed from a polymer that reacts in an aqueous environment. When used to treat an aneurysm, the foam is placed into contact with at least a portion of an exterior surface of the medical device and/or the tissue surface of the aneurysm.