Tissue expanders having integrated drainage and infusion assemblies

A tissue expander having an integrated drain includes an outer shell having an opening and one or more drainage holes. An injection port is disposed in the opening of the shell and forms a fluid-tight seal with the shell. The injection port includes a needle guard having a needle guard base with a top surface, and a barrier membrane that overlies the top surface of the needle guard base. The barrier membrane defines an inflation chamber located between the top surface of the needle guard base and a bottom surface of the barrier membrane, and a drainage chamber overlying a top surface of the barrier membrane. The tissue expander includes one or more inflation ports that are in fluid communication with the inflation chamber for inflating and deflating the outer shell with a first fluid. A drainage conduit is in fluid communication with and extends between the drainage chamber and the one or more drainage holes for draining a second fluid from outside the shell.