Diagnostic yield of weekly laboratory testing in the outpatient management of hypertensive disorders of pregnancy

Abstract

Weekly laboratory testing in the outpatient management of Hypertensive Disorders of Pregnancy (HDP) has been recommended by ACOG for the last decade with little evidence regarding its utilization. Our objective was to compare the diagnostic yield of weekly laboratory episodes in symptomatic versus asymptomatic patients with HDP. Retrospective cohort study of singleton pregnancies with HDP managed outpatient from 1/2014 to 7/2021. Our primary outcome was the prevalence of a positive laboratory test resulting in delivery or inpatient management in patients that were symptomatic versus asymptomatic at the time of each laboratory episode. A positive test was defined as a laboratory value diagnostic of preeclampsia with severe features. Patients were considered symptomatic if maternal symptoms (headache, scotoma, RUQ pain) or elevated blood pressure were reported. Secondary outcomes included adverse maternal outcomes and a cost analysis performed using Medicare fee schedule costs of each lab test. The prevalence of 1° and 2° outcomes were compared using chi square test. A total of 543 patients were included in the study. In total, 1082 laboratory episodes were performed: 356 (33%) in symptomatic and 726 (67%) in asymptomatic patients. Overall, the rate of abnormal lab results was low (1%), but the percentage of positive tests was higher in symptomatic versus asymptomatic patients (2.8% versus 0.1%, p< 0.01). Only 1 patient (0.2%) had an adverse maternal outcome, intrapartum placental abruption. The overall cost to screen asymptomatic patients was higher than symptomatic patients ($12,363.78 versus $6,062.68), and the cost per abnormal test was lower for symptomatic patients ($1,212 versus $12,363.78). The diagnostic yield of weekly laboratory evaluation for HDP was low overall, however significantly higher in patients that were symptomatic. Eliminating routine weekly laboratory evaluation of asymptomatic patients with HDP would eliminate approximately 67% of laboratory episodes and result in significant cost savings with minimal effect on the overall diagnostic yield.View Large Image Figure ViewerDownload Hi-res image Download (PPT)