An apparatus for trapping bubbles in blood flowing in a circuit, such as blood in an extracorporeal circuit, is provided. The apparatus includes a housing which defines a substantially vertical chamber. Blood is introduced into the chamber through an inlet tube extending downwardly into the chamber and is removed from the chamber at an exit port near the lower end of the housing. A diverter having a container base and rim is positioned within the chamber. Blood is introduced near the container base. The blood is redirected upward upon contact with the container base and is then redirected downward over the rim. The redirection of blood flow provides an opportunity for bubbles in the blood to separate from the blood in the chamber and also helps prevent stagnation of blood in the chamber which might otherwise lead to clotting and separation of the blood.
Blood is introduced into a chamber of the apparatus in a generally downward direction below the level of blood already present in the chamber. The blood is then directed in a generally upward direction, after which it is redirected in a generally downward direction. The reversal of blood flow provides an opportunity for bubbles in the blood to separate from the blood. Thereafter the blood and bubbles are collected.