The application relates to a blood collection device comprising: a cannula hub (10) defining a chamber (28)； an inlet cannula (12) defining an axis and having a distal end and a lumen extending therethrough, the inlet cannula being mounted to the cannula hub such that the distal end of the inlet cannula is external of the cannula hub and such that the lumen through the inlet cannula communicates with the chamber； an outlet cannula (14) having a proximal end and a lumen extending therethrough, the outlet cannula being mounted to the cannula hub such that the proximal end of the outlet cannula is external of the cannula hub and such that the lumen of the outlet cannula communicates with the chamber； a closed sleeve (34) mounted over a portion of the outlet cannula disposed externally of the cannula hub； and a venting mechanism (38) providing communication between the chamber and ambient surroundings.
