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Maternal fetal hemorrhage of greater than or equal to 0.1 percent predicts preterm labor in blunt maternal trauma

      Objective

      To evaluate factors associated with preterm labor in blunt trauma during pregnancy.

      Study design

      Prospective registry of women admitted to University of Maryland for blunt maternal trauma from 2001-2003. All women were > or = 20 weeks' gestation. All underwent cardiotocodynamometry (CTD) and Kleihauer Betke (KB) testing regardless of RH status. Maternal age, race, gravity, parity, injury type, injury severity score (ISS), trauma-related injury severity score (TRISS), abbreviated injury score (AIS), revised trauma score (RTS), contractions, preterm labor (PTL), placental abruption, maternal fetal hemorrhage (MFH), fetal death, placental, uterine and fetal injury were recorded. Chi-square, Spearman's rho, Fisher's exact test, and logistic regression compared those with and without transplacental hemorrhage (TPH) shown by positive KB test.

      Results

      48 women were identified. Overall, 27 of 48 women had negative CTD, none had preterm labor (PTL). 21 women had documented contractions; 7 of these had PTL characterized by progressive cervical change. All 7 had a positive KB of > or + 0.1%. Of 21 women with documented contractions, 19 of these had a positive KB test and only 2 with a + CTD had a negative KB. None of the patients with a KB <.1% had preterm labor (PTL). Tocolysis was successful in all cases of PTL. Compared to other sites of trauma, spinal injury was more often associated with PTL (P<0. 006). Logistic regression of combined risk factors showed KB of >.1 was the single factor associated with PTL (P = 0. 002, likelihood ratio of 11.2). None of the trauma scoring system correlated with PTL or positive KB.

      Conclusion

      A positive KB test >0.1% following maternal trauma is highly predictive of preterm labor. The high success rate of tocolysis mostly reflects the resolution of TPH and the degradation of the causative agent thrombin.