Featured is a vascular access device such as an IV catheter device including a housing, a tubular member, a seal member, a compression member, and a securing mechanism. The housing includes a proximal and distal portion and a chamber that extends between the proximal and distal housings. The tubular member is coupled to the housing distal portion so it is fluidly coupled to the chamber. The seal member is disposed within the chamber and the securing mechanism secures the seal member distal end to the housing proximal portion so the seal member is sealingly and compressibly retained between a chamber proximal end and the securing mechanism. Such a seal member also forms a septum, which is compressed by the compression member to prevent seepage upon removal of a stylet.