Instrument delivery device with nested housing

An instrument delivery device for advancing an instrument into a vascular access device, the instrument delivery device comprising:

• an outer housing defining an inner volume and having a proximal end and a distal end;
• a connector positioned at the distal end of the outer housing and comprising a projection member protruding out from the outer housing configured to mate with an access connector of the vascular access device;
• an inner housing having a proximal end and a distal end, with the distal end positioned within the inner volume and engaged with a proximal end of the instrument, wherein the inner housing is configured to move relative to the outer housing such that a distal movement of the inner housing moves the instrument from a first position, in which a distal end of the instrument is disposed within the outer housing, to a second position, in which the distal end of the instrument is disposed beyond the distal end of the outer housing and the projection member;
• and
• a fluid flow preventing seal provided in or adjacent the connector and configured to prevent a transfer of fluid between the vascular access device and the inner volume of the outer housing,
• wherein the inner housing is slideably received within the outer housing in a telescoping relationship.