A point-of-care urine test to predict adverse maternal and neonatal outcomes in Asian women with suspected pre-eclampsia

To assess the predictive value of the urine Congo red dot test (CRDT) in ruling in and out composite adverse maternal and neonatal outcomes in Asian women presenting with suspected pre-eclampsia (PE). Urine CRDT result at admission and pregnancy outcomes were prospectively documented in 251 women who presented with signs/symptoms of suspected PE after 20 weeks of gestation between January 2020 and December 2022. All admissions were managed according to internally agreed protocols and all clinicians were blinded to CRDT result. Composite adverse maternal outcome included PE, postpartum hemorrhage, intensive care unit admission and maternal death. Composite adverse neonatal outcome included small for gestational age, preterm birth, Apgar score < 7 at 5 minutes, perinatal depression, respiratory distress syndrome, necrotising enterocolitis, intraventricular hemorrhage, sepsis, neonatal intensive care unit admission and neonatal death. 244 (97.2%) women with suspected PE on admission had a negative CRDT. Rates of composite adverse maternal and neonatal outcomes in CDRT negative women were 103/244 (42.2%) and 165/244 (67.6%) respectively. Corresponding rates of composite adverse maternal and neonatal outcomes in those with a positive CRDT were both 7/7 (100%). The negative predictive value (NPV) of a negative urine CRDT test for adverse maternal outcome was 141/244 (57.8%, 95%CI 48.6%-68.2%) whilst that for adverse neonatal outcome was 79/244 (32.4%, 95%CI 25.6%-40.4%). The positive predictive values of a positive urine CRDT for adverse maternal and neonatal outcome were both 7/7 (100.0%). A negative CRDT alone has low NPV for adverse maternal and neonatal outcomes in women with suspected PE. Further studies are required to evaluate its clinical utility combined with maternal serum anti-angiogenic and pro-angiogenic proteins in improving the prediction of adverse outcome.