Elevated admission white blood cell count in pregnant trauma patients: an indicator of ongoing placental abruption.

Placental abruption (PA) is a common cause of fetal demise in pregnant trauma patients. Diagnosis of PA may be difficult, and multiple diagnostic clues are currently used including uterine/abdominal pain and tenderness, bleeding, maternal hemodynamic instability, and evidence of PA by ultrasonography or other fetal monitoring. Although diagnosis may be problematic fetal and maternal survival are dependent on early diagnosis and intervention. The purpose of this study is to determine predictive factors present at admission associated with PA in trauma victims. Records of all pregnant trauma patients admitted to Wake Forest University Baptist Medical Center over a 5-year period were reviewed for injury characteristics and outcome. Inclusion criteria included a confirmed pregnancy and fetal disposition. Specific admission parameters evaluated included temperature, heart rate, systolic blood pressure, partial pressure of CO2 in arterial blood, total white blood cell count (WBC) and differential, hematocrit, base deficit, and lactic acid. PA is defined as a spontaneous abortion in the first trimester or abruptio placenta in the second or third trimester. Between April 1, 1996 and October 30, 2000, 30 patients met study criteria. Six of 30 patients were found to have PA (20%). Of the studied parameters WBC was significantly elevated in PA patients (27 +/- 4.6 vs 17 +/- 7.8 WBC x 10(3)/mm3; P = 0.005) as was band count (10 +/- 6.6% vs 4 +/- 6.1%; P = 0.03). Hematocrit was lower in the PA group (27 +/- 4.3% vs 32 +/- 5.4%; P = 0.04). Within this group of variables which differed on univariate analysis, WBC was the best discriminator between patients with and without PA (sensitivity 100%, specificity 79%, negative predictive value 100%, and positive predictive value 54%). In pregnant trauma patients WBC >20,000/mm3 on admission should raise suspicion of the possibility of PA, and close monitoring is warranted. Conversely WBC <20,000/mm3 rules out PA in the pregnant trauma patient (negative predictive value of 100%).