Internal needle

An indwelling needle assembly comprising:

• an outer cannula having a proximal end, a distal end and a housing attached to the proximal end, the housing defining an interior space which decreases in diameter towards the proximal end;
• an inner needle having a sharpened distal tip portion and a proximal end secured to a hub;
• and
• a needle tip protector positioned within the interior space of the housing and slidably positioned about the inner needle, the needle tip protector having a first end defining a first through-hole of a first diameter and a second end defining a second through-hole of a second diameter smaller than the first diameter;
• and
• at least one inwardly movable blocking member supported on the needle tip protector, wherein the inner needle includes an enlarged diameter adjacent the distal tip portion which is larger than the first diameter but smaller than the second diameter;
• wherein withdrawing the inner needle from the outer cannula in a proximal direction causes the enlarged diameter of the inner needle to engage the needle tip protector adjacent the second through-hole to effect withdrawal of the needle tip protector from the housing, wherein withdrawal of the needle tip protector from the housing causes the at least one blocking member to move inwardly to block the distal tip portion of the inner needle.