Urinary Congophilia in Pre-Eclampsia: A Potential Diagnostic Biomarker.

AIM: Pre-eclampsia (PE) causes significant maternal and neonatal morbidity and mortality worldwide, particularly in low- and middle-income countries (LMICs). Current diagnostic methods, such as blood pressure monitoring and proteinuria measurement, have poor sensitivity and specificity. Although biomarkers like PlGF and sFlt-1 improve diagnostic accuracy, their clinical value is limited by cost and infrastructural constraints. The Congo red dot (CRD) test, which identifies misfolded proteins via urinary congophilia, has emerged as a low-cost, noninvasive alternative for detecting PE.

METHODS: This review evaluated the diagnostic performance of the CRD test by synthesizing evidence from studies across diverse populations, including India, China, and South Africa. Methodologies encompassed prospective cohorts, case-control designs, and meta-analyses, with a focus on sensitivity, specificity, and comparative efficacy against conventional screening tools.

RESULTS: Results indicate that the CRD test achieves high diagnostic accuracy, with reported specificity of 89.2% and sensitivity of 80.2%. The assay provides rapid results (< 3 min) without specialized equipment, demonstrating effectiveness in LMICs. However, performance variability was observed in late-onset PE, and comparative studies yielded conflicting data regarding its superiority over urinary dipstick analysis. Additionally, challenges persist in differentiating PE from other hypertensive disorders with overlapping proteinuria.

CONCLUSION: The CRD test represents a promising diagnostic tool for PE in LMICS with limited access to advanced diagnostics. Further large-scale validation studies are required to standardize protocols, establish gestational age-specific thresholds, and clarify its role in differentiating PE from confounding conditions. Integration with existing biomarkers may enhance its clinical adoption and diagnostic precision.