a medical solution container includes a bag portion for storing solution and a header portion which incorporates an improved outlet port in communication with the bag portion for receiving and holding a spike from an administration set . the outlet port has , at a distal end from the bag portion , a generally inwardly inclined tapered annular collar which , at its widest diameter portion , joins a substantially cylindrical coaxial bore section . the cylindrical bore section has a first section with a reduced diameter which adjoins a second section having an enlarged diameter . the second section is located at an end of the outlet port proximate the bag . a pierceable diaphragm for sealing the outlet port is supported at the junction of the reduced and enlarged diameter bore sections and lies substantially in a plane which is at an angle to a normal to the insertion direction of the spike or the axial direction of the cylindrical bore . by providing the diaphragm at an angle , which is preferably between about 5 ° and about 20 °, the force required to pierce the diaphragm with the spike is reduced while a reliable holding force is maintained after the spike has been inserted , to frictionally hold the spike in the outlet port .