BACKGROUND:Children commonly present to Emergency Departments (ED) with a non-blanching rash in the context of a feverish illness. While most have a self-limiting viral illness, this combination of features potentially represents invasive serious bacterial infection, including meningococcal septicaemia. A paucity of definitive diagnostic testing creates diagnostic uncertainty for clinicians; a safe approach mandates children without invasive disease are often admitted and treated with broad-spectrum antibiotics. Conversely, a cohort of children still experience significant mortality and morbidity due to late diagnosis. Current management is based on evidence which predates (i) the introduction of meningococcal B and C vaccines and (ii) availability of point of care testing (POCT) for procalcitonin (PCT) and Neisseria meningitidis DNA. METHODS:This PiC study is a prospective diagnostic accuracy study evaluating (i) rapid POCT for PCT and N. meningitidis DNA and (ii) performance of existing clinical practice guidelines (CPG) for feverish children with non-blanching rash. All children presenting to the ED with a history of fever and non-blanching rash are eligible. Children are managed as normal, with detailed prospective collection of data pertinent to CPGs, and a throat swab and blood used for rapid POCT. The study is running over 2 years and aims to recruit 300 children. PRIMARY OBJECTIVE:Report on the diagnostic accuracy of POCT for (i) N. meningitidis DNA and (ii) PCT in the diagnosis of early MD Report on the diagnostic accuracy of POCT for PCT in the diagnosis of Invasive bacterial infection Secondary objectives: Evaluate the performance accuracy of existing CPGs Evaluate cost-effectiveness of available diagnostic testing strategies Explore views of (i) families and (ii) clinicians on research without prior consent using qualitative methodology Report on the aetiology of NBRs in children with a feverish illness DISCUSSION: The PiC study will provide important information for policy makers regarding the value of POCT and on the utility and cost of emerging diagnostic strategies. The study will also identify which elements of existing CPGs may merit inclusion in any future study to derive clinical decision rules for this population. TRIAL REGISTRATION:NCT03378258 . Retrospectively registered on December 19, 2017.