The failure of postinjection Rh immune globulin titers to detect large fetal-maternal hemorrhages

The inadequacy of current testing methods for fetal-maternal hemorrhage (FMH) had led to the use of postinjection titers of Rh immune globulin (RhIg) to assess large FMH. The authors have studied the titers of 30 RhIg recipients who received 300 μg of RhIg. The 48-hour postinjection titer was compared with the size of bleed as measured by Du testing and the enzyme-linked antiglobulin test (ELAT). Patients had less than 30 mL FMH suggested by negative Du and immune rosette tests. The postinjection titer of RhIg ranged from 0 to 32 when tested by saline-antiglobulin technics. When the size of the bleed was compared with the titer, no correlation could be found. The authors believe that postinjection titers of RhIg should not be used to detect a large FMH.