C-Reactive Protein
Strong evidence supports that C-reactive Protein is a strong rule-in and rule-out marker for patients with suspected surgical site infections.

Rationale
Multiple high-quality studies and meta-analysis of the study data support the use of C-reactive protein in the diagnosis of surgical site infection (Bottner et al 2007, Glehr et al 2013, Cipriano et al 2012, Jacovides et al 2011). Several moderate quality studies (Yi et al 2015, Piper et al 2009, 2010, Bedair et al 2011) also support its use. It was found to be both sensitive and specific in detecting periprosthetic infection and served as an accurate screening tool, with a positive or negative value demonstrating the likelihood of the presence or absence of infection. Studies vary with respect to the timing and thresholds used to diagnose infection. Both Yi et al 2015 and Bedair et al 2011 confirmed its utility during the early postoperative period. Despite this variation, it has proven its accuracy across investigations. While cutoff values at which an infection is diagnosed vary between studies, and based on time postoperatively it has been shown to be a superior screening test relative to other serological studies.