The role of serial blood tests during expectant management of early preeclampsia with severe features

Abstract Background Expectant management of early‐onset preeclampsia with severe features (<34 weeks’ gestation) requires close maternal surveillance. Although serial testing is routinely performed, recommendations regarding testing frequency vary across professional societies and the clinical utility and financial impact of frequent testing during expectant management remain uncertain. Objective To describe the role of serial blood tests in guiding delivery decision‐making in preeclampsia with severe features, and to assess the health costs of these serial blood tests. Study Design A retrospective cohort study of singleton pregnancies diagnosed with preeclampsia with severe features between 23 and 33 weeks at a level IV academic maternity center. Patients with contraindications to expectant management were excluded. Delivery indications were categorized by the contribution of blood test abnormalities: no abnormal blood tests contributing to delivery; blood test abnormalities detected once the decision for delivery was made, but not indication for delivery; and blood test abnormalities as the indication for delivery. Primary outcome was delivery prompted by abnormal blood test findings. Secondary outcomes included charges associated with serial testing. Data analysis included percent with 95% confidence intervals (CIs) or median with interquartile ranges (IQRs). Results A total of 370 patients met inclusion criteria. Only five (1.4%; 95% CI, 0.4–3.1) had abnormal blood test values (transaminitis and/or thrombocytopenia) prompting delivery decisions, all appearing within 4 days of admission. Abnormal blood testing was not an indication for delivery for most patients ( N = 325; 87.8%; 95% CI, 84.1–91.0). For 40 patients (10.8%; 95% CI, 7.8–14.4), blood test abnormalities were detected after decision for delivery was made. The median number of blood tests per patient was 10 (IQR 6–14), and blood testing charge per patient was $5030 (IQR 3018–7042). The total charge for blood testing was $2.176 million over the study period. Conclusion Among 370 patients with early‐onset preeclampsia with severe features managed expectantly, only 1% of the cohort had blood test abnormalities as the sole indication for delivery. All other patients were delivered either because of maternal‐fetal indications or developed blood test abnormalities occurring in association with other indications for delivery. Finally, serial blood testing in this setting resulted in total charges of $2.176 million over 9 years. Based on this large cohort, there is a need to reconsider the frequency of blood testing in the absence of new‐onset symptoms or worsening severe features.