As previously mentioned - a midline catheter is a peripheral IV (ie not a central line). The tip (or end - where the medication infuses) - is in the mid basilic/cephalic vein - it does not extend past the axilla. They usually are about 20cm long - and are intended for long term peripheral access (up to ~6 months)..because they are not a central line - they should be used for non-vesicant infusions and are not suitable for blood draws - if they require either of these, they should have a PICC or other CVC placed. Midlines aren't used much anymore as PICC's are becoming more abundant - PICC's usually are a better choice - longer life, more functionality etc... Brent.