Utility of Weekly Laboratory Monitoring in the Expectant Management of Hypertensive Disorders of Pregnancy

Our retrospective cohort study evaluates the diagnostic yield of weekly laboratory surveillance in outpatient management of hypertensive disorders of pregnancy (HDP) based on patient clinical status at the time of laboratory testing. The study included 459 patients and 1,082 laboratory episodes: 356 (32.9%) episodes were performed in the setting of concerning clinical findings and 726 (67.1%) when the patient was asymptomatic. Overall, the diagnostic yield for abnormal laboratory values (n=11) was 1.0% (95% CI 0.4-1.6%) of all assessments performed and 2.4% (95% CI 1.0-3.8%) among all patients in the cohort. The prevalence of abnormal test results was higher in patients with clinical findings (2.8%, 95% CI 1.1-4.5%) compared with those who were asymptomatic (0.1%, 95% CI 0-0.2%) ( P <.01). Clinical findings suggestive of worsening disease had a 91% sensitivity (95% CI 59-100%) and a 99% (95% CI 99-100%) negative predictive value for abnormal laboratory values. Directed screening based on signs and symptoms, rather than universal weekly screening, may be a potential strategy to lower costs and reduce multiple blood draws for patients with HDP, because there is a low diagnostic yield for this practice.