Simplify the following text for a Grade 13 native English-speaking person.
Original: In medicine , a central venous catheter ( `` central line '' , `` CVC '' , `` central venous line '' or `` central venous access catheter '' ) is a catheter placed into a large vein in the neck ( internal jugular vein or external jugular vein ) , chest ( subclavian vein ) or groin ( femoral vein ) .
Simplified: A central venous catheter ( CVC ) or `` central line '' is a catheter put in a large vein in the neck , chest , or groin when a patient needs close cardiovascular monitoring , for assessment of fluid status , and so that intravenous drugs and fluids can be given to the patient more effectively . The veins most commonly used are the internal jugular vein , the subclavian vein , and the femoral vein .