Urine Test Allows for Rapid Preeclampsia Diagnosis

Hypertensive disorders affect 15% of pregnancies and account for one quarter of the antenatal admissions. Preeclampsia (PE) is a multisystem disorder specific to human pregnancy, and its incidence varies from 5% to 60% of gestations, depending on maternal co-morbidities.

PE has a large spectrum of medical signs and symptoms resulting in a range of clinical phenotypes and outcomes, making a diagnosis on available clinical and laboratory parameters challenging. Hypertension and proteinuria are non-specific, and thus major challenges arise when differential diagnosis includes chronic hypertension, endocrine, and kidney diseases.

Scientists at The Ohio State University College of Medicine (Columbus, OH, USA) recruited 346 consecutive pregnant patients from the labor and delivery (L&D) triage unit at Wexner Medical Center (Columbus, OH, USA) and followed prospectively until delivery from July 2014 to July 2015. Eligible, consenting women were approached for enrollment by certified research nurses immediately after their presentation to the triage area before initiation of the clinical work-up for PE. The team designed, developed and validated a simple bedside, paper-based urine test kit, which they named the CR Dot (CRD) Paper Test.

Of the approached women, 353 (98%) agreed to participate. Patients were consented to provide a urine and matched venous blood sample. Refusal to provide a blood sample by 107 women was not an exclusion criterion. Urine was collected in sterile containers and tested fresh without processing in the triage area. The result of the CRD Paper Test was read at three minutes. The team used immunoassays to measure levels of urine and serum soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF). The sFlt-1/PlGF ratios were calculated and used for comparison with the results of the CRD Paper Test.

The team reported that 89 of the pregnant women had a clinical diagnosis of preeclampsia. Of those, 79% were induced due to preeclampsia, with an average age of delivery at 33 weeks gestation. The team found the CRD test was superior to the other biochemical tests, with an accuracy rate of 86%. Urine congophilia was detected in 14 (12%) patients admitted with an uncertain diagnosis and in only 59 (58%) patients admitted with a diagnosis of PE established or confirmed in triage. There were nine (8%) instances of positive congophilia in the group of patients discharged home absent PE. The CRD Paper Test was positive in just four (36%) patients discharged with a diagnosis of PE.

Kara M. Rood, MD, a maternal-fetal medicine physician and first author of the study, said, “This is the first clinical study using the point-of-care, paper-based Congo Red Dot (CRD) diagnostic test, and the mechanism proved superior in establishing or ruling out a diagnosis of preeclampsia. Our findings will have a huge impact on the health of women and children.” The study was published on March 1, 2019, in the journal EClinicalMedicine.

Related Links:
The Ohio State University College of Medicine
Wexner Medical Center