An apparatus for oxygenating blood including a housing and an oxygenator bundle. The housing defines a primary chamber, a blood inlet port open to the primary chamber, and a blood outlet region. The outlet region includes a blood outlet port, an outlet chamber open to the outlet port, and a partition. The partition establishes spaced apart, first and second passageways from the primary chamber to the outlet chamber. The oxygenator bundle is disposed within the primary chamber. A blood flow path is formed from the blood inlet port, through the oxygenator bundle and to the blood outlet port, and includes first and second outlet flow paths within the outlet chamber via the first and second passageways, respectively. The first and second outlet blood flow paths merge at the blood outlet port. A dual port blood outlet is created, increasing mixing of blood immediately upstream of the outlet port.