Source: Sharon Bord, MD, Department of Emergency Medicine, The Johns Hopkins University School of Medicine, Maryland, USA Placement of an intravenous (IV) catheter is one of the key procedures in medicine. The IV catheter allows patients to receive critical medications, including pain medicine, insulin, antibiotics, blood products, and fluids for rehydration. Additionally, placing an IV catheter allows for blood samples to be obtained, which can be sent to the laboratory for testing and evaluation. A majority of peripheral IV lines are placed in the superficially located veins of the upper extremities. IV catheters can be placed in any superficial vein from the upper arm to the hand (though the veins in the antecubital fossa are larger than those in the hand). IV catheters can be placed in the lower extremities as well; however, this procedure should be performed with caution in patients with a history of diabetes or poor peripheral circulation.