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Preeclampsia Screening Should Not Include Proteinuria

Preeclampsia affects approximately 4% of pregnancies in the United States. Preeclampsia is defined as the onset of hypertension occurring after 20 weeks of gestation, combined with either proteinuria or other signs or symptoms involving multiple organ systems. Preeclampsia causes adverse health effects in both mothers and infants. Serious maternal complications include stroke, retinal detachment, HELLP syndrome and eclampsia. The latter can cause maternal brain damage, aspiration pneumonia, pulmonary edema, placental abruption, disseminated coagulopathy, acute renal failure, cardiopulmonary arrest, and coma. Adverse perinatal outcomes for the fetus and newborn include intrauterine growth restriction, oligohydramnios, low birth weight, and stillbirth. Preeclampsia leads to early induction of labor or cesarean delivery and subsequent preterm birth.

The United States Preventive Services Task Force (USPSTF) recently updated their recommendation on screening for preeclampsia during pregnancy. USPSTF found that screening and early treatment reduce maternal and perinatal morbidity and mortality. USPSTF recommends screening for preeclampsia with blood pressure measurements throughout pregnancy. The agency did not find sufficient evidence to support point of care urine testing for proteinuria. Urine dipstick tests for proteinuria had sensitivity ranging from 0.22 to 1.00 and specificity ranging from 0.36 to 1.00. Sensitivity of the protein to creatinine ratio ranged from 0.65 to 0.96 and specificity ranged from 0.49 to 1.00. These performance statistics were obtained by screening women with preeclampsia and not all pregnant women. 

According to USPSTF, proteinuria measurement should be reserved for diagnosis of preeclampsia. Recently revised criteria for the diagnosis of preeclampsia include; elevated blood pressure (140/90 mm Hg or greater on 2 occasions after 20 weeks of gestation) and proteinuria, which is defined as 300 mg/dL of protein or greater in a 24 hour urine collection or a protein to creatinine ratio of 3 mg/g or greater. If quantitative analysis is not available, a urine protein dipstick reading of >1 can be substituted. If proteinuria is not present, then the presence of thrombocytopenia, renal insufficiency, abnormal liver function, pulmonary edema, and cerebral or visual symptoms can be used to make the diagnosis.

USPSTF’s revised recommendation is similar to the recommendation of the American College of Obstetricians and Gynecologists. ACOG recommends obtaining blood pressure measurements at every prenatal visit and using a detailed medical history to evaluate for risk factors for preeclampsia.

US Preventive Services Task Force, Screening for Preeclampsia. JAMA 2017;317:1661-67.

American College of Obstetricians and Gynecologists. Hypertension in Pregnancy. Washington, DC: American College of Obstetricians and Gynecologists; 2013. 

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