抽血 is a separable verb (离合词) meaning 'to draw blood'. The verb 抽 and the object 血 can split when you insert aspect markers (了, 过), measure words (次, 管), or duration (三分钟) between them — for example, 抽过血 ('have drawn blood') or 抽了三管血 ('drew three vials of blood'). You can also put the action before a location: 到医院抽血 ('go to the hospital to have blood drawn'). The person whose blood is drawn is usually introduced with a possessive or location phrase: 抽我的血 ('draw my blood') or 在手臂上抽血 ('draw blood from the arm').