Is one elevated blood pressure enough? A retrospective analysis of preeclampsia labs sent from the emergency room

Background: In the emergency department, where providing efficient, cost-effective medical care is becoming increasingly important, care of pregnant women with elevated blood pressures is varied.Currently, there are no recommendations designating when laboratory evaluation for preeclampsia should be initiated in the emergency department.Objective: This study sought to compare the incidence of positive laboratory findings in women with isolated initial versus repetitive elevated blood pressure in the emergency department.Study Design: This retrospective cohort included women ≥ 20 weeks gestation who presented to a tertiary care emergency department between January and July 2014 with an elevated blood pressure (≥ 140 mmHg systolic or ≥ 90 mmHg diastolic) and without significant co-morbidities (chronic hypertension, diabetes mellitus, preexisting renal or liver disease, or thrombocytopenia).The primary outcome was abnormal laboratory values suggesting preeclampsia (platelets, creatinine, liver enzymes, and urine protein/creatinine ratio).The association between one versus more than one elevated blood pressure in the emergency department and abnormal laboratory evaluation for preeclampsia was evaluated using Fisher's exact test.Secondary outcomes included diagnoses of preeclampsia at emergency department discharge or delivery.Results: Of 4,208 charts screened, 271 met inclusion criteria and had complete preeclampsia labs sent per hospital policy.Of these, 122 had an isolated elevated blood pressure and 149 had more than one elevated blood pressure.Women with multiple elevated blood pressures were more likely to have abnormal preeclampsia labs than women with an isolated elevated blood pressure, 34.2% vs 15.6% (p<0.001).Only one woman with an isolated elevated blood pressure had a laboratory abnormality consistent with a severe feature of preeclampsia.Compared to women with an isolated elevated blood pressure, women with multiple elevated blood pressures were more likely to carry the diagnosis of preeclampsia at the time of discharge from the emergency department (14.8% vs 5.3%, p=0.003), and at the time of delivery (17.9% vs 4.2%, p<0.001).Conclusion: Women with multiple elevated blood pressures are at significantly higher risk for lab abnormalities consistent with preeclampsia and at significantly greater risk for developing preeclampsia by delivery than women with only one elevated blood pressure in the emergency department.Delaying serum laboratory evaluation for preeclampsia in patients presenting to the emergency department until two abnormal blood pressures are noted may be reasonable to decrease costs without significantly increasing morbidity.