Biomarkers for Necrotising Enterocolitis—Are We There Yet?

Necrotising enterocolitis (NEC) remains an important disease for neonatologists, with diagnostic and management challenges and impacts on mortality and neurodisability. NEC can present in a non-specific way, and differentiating from late-onset sepsis (LOS), focal perforation (FIP) and feed intolerance can be difficult. Biomarkers have been extensively explored as a way to help more definitively identify NEC or rule it out. Many biomarkers that have been studied are blood biomarkers, and several other extensive reviews of biomarkers in NEC exist. In this narrative review, we focus on non-invasive samples, namely stool, urine and saliva, and on tests that are already available as point-of-care tests (POCTs) or are likely to be available as POCTs soon given current technologies. Faecal calprotectin and urinary intestinal fatty acid-binding protein (IFABP) have the most data to currently support their use in larger multi-centre studies and appear most likely to achieve translation into clinical practice. Saliva appears the most under-researched potential source of a non-invasive POCT for a biomarker for NEC. For faecal calprotectin and urinary IFABP, data that are most lacking relate to specificity, particularly the performance of these tests to differentiate NEC from FIP or LOS (occurring in the absence of NEC). We suggest a study design to facilitate moving towards the clinical use of non-invasive biomarkers in NEC.