a single port is provided for a container such as an i . v . bag which can serve both as an additive port and also as an administration port . the combined administration and additive port has an inner diaphragm portion which is in open communication with the solution in the container and an outer resealable stopper unit which when pierced by a needle of a hypodermic syringe is self - sealing . the outer resealable unit is removable from the port so that the port subsequently serves as the usual administration port when utilizing the standard i . v . administration equipment .