Most patients admitted to an intensive care unit undergo central venous catheterization (CVC) or already have received a CVC. Over 5 million CVC placements are performed each year in the United States. An indication of central venous access is for example when peripheral veins are inaccessible or for the administration of potent vasoactive drugs such as norepinephrine or dopamine. Three anatomical sites are frequently used to insert a CVC: the subclavian, jugular and femoral site. Although central venous catheterization offers multiple advantages, it is associated with adverse events that could be hazardous for patients. Mechanical, infectious or thrombotic complications could occur. Most common mechanical complications include arterial puncture, hematoma and pneumothorax. Besides mechanical complications, malposition of a CVC could also lead to complications, including phlebitis, perforation, and venous thrombosis or occlusion. Malposition of the CVC tip into the right atrium could also lead to arrhythmias. The frequency of primary mal-positioning has been shown to be up to 3.7%. A recent multicenter trial, which included 3471 catheters in 3027 patients, showed that subclavian-vein catheterization was associated with a lower risk of bloodstream infection and symptomatic thrombosis but involved a higher risk of pneumothorax as compared to jugular-vein or femoral-vein catheterization. The risk of mechanical complications in subclavian, jugular or femoral catheterization was 2.1%, 1.4% and 6% respectively.