An O-positive mother gave birth to an A- negative baby. After 24 hours the newborn's bilirubin level rose to 18 mg/dL. A DAT performed on the cord blood specimen was positive with polyspecific AHG and anti-IgG reagents. It is probable that from maternal circulation is coating the newborn's red blood cells.
Due to a short supply of O-negative packed cells, an Rh-negative patient was transfused with 1 unit of Rh-positive red blood cells. Calculate the number of Rh-immune globulin vials needed to protect against 250 mL of Rh-positive packed cells.