Introduction
Trauma during pregnancy occurs in 1 to 12% of
pregnancies1. In an attempt to optimize maternal and
neonatal outcomes, predictors of serious perinatal consequences such as
placental abruption, preterm delivery, lethal fetal injury, and uterine
rupture, in addition to the full range of maternal injuries, have been
sought2–6. The most significant risk factor for
adverse maternal and neonatal outcomes is severe injury. Fortunately
however, severe trauma occurs in only a minority of pregnant trauma
patients7.
As most trauma cases during pregnancy are mild, continuing exploration
of risk factors for adverse maternal and neonatal outcomes in this
setting is clinically important8. We hypothesized that
feto-maternal hemorrhage (FMH), also called transplacental hemorrhage
(TPH), could possibly be associated with the risk of adverse maternal
and neonatal outcome.
FMH may be diagnosed via flow cytometry (FCM) for detection and
quantification of fetal red blood cells, or by Kleihauer–Betke test (KB
test). FCM is an accurate method to evaluate this type of
bleeding9–14 , based on the identification of fetal
erythrocytes containing hemoglobin F (HbF) with an anti-HbF monoclonal
antibody. The FCM method can analyze a very high number of erythrocytes,
improving the sensitivity and specificity of the KB
test15,16. Massive TPH associated with complete
placental abruption is rare and clinically evident, making FCM testing
superfluous. FCM testing is commonly used to detect TPH in pregnant
trauma women. Some studies have suggested that a positive KB test in the
setting of trauma during pregnancy may be predictive of adverse
perinatal outcomes, however other studies have shown
differently17,18. We failed to find similar studies
assessing the utility of FCM in this setting.
In this study, we aimed to assess whether positive FCM is associated
with adverse perinatal outcomes in pregnant patients experiencing mild
trauma.