Answer: A penetrating injury creates an opening in the artery and forms a hematoma. This hematoma develops a wall around it and the hematoma liquefies and forms a pulsating "bubble" on the artery. This is called a pseudoaneurysm. A pseudoaneurysm, like any aneurysm, can rupture and cause bleeding or loss of limb. The most common penetrating "injury" of the femoral artery occurs during cardiac catheterization performed via the femoral artery or after femoral central line attempt.
