*9.2.1 White blood cells count*

The role of **white blood cells (WBC)** in the early diagnosis of CAL is still controversial due to its nonspecific nature and wide variability. WBC may increase after the surgical injury or signaling a postoperative complication, regardless of whether they are medical (pneumonia or urinary infection) or surgical (surgical site infection or organ/ space infection), among others. Warschkow et al. found that the WBC level had a fair contribution to the early detection of septic complications, offering a lower diagnostic accuracy than the plasma CRP [130].

### *9.2.2 Eosinophil cells count*

**Eosinopenia** (ECC) is a common inflammatory response in acute infections. It has been proposed as a useful biomarker to identify severe sepsis and to distinguish it from other causes of SIRS. Shaaban et al. consider an ECC cutoff point of 50 cells/ mm3 a good marker of sepsis presence [131]. Recently, ECC monitoring was proposed as a marker for positive evolution in septic patients under antibiotic therapy [132].

Due to its availability, fastness, simplicity, and low cost, ECC can be used in the daily clinical diagnosis of sepsis [133]. However, its specific usefulness in the early diagnosis of CAL is yet to be established.

### *9.2.3 C-reactive protein*

**Plasma C-reactive protein (CRP)** is an acute phase reactant with liver synthesis. In healthy individuals, plasma levels are under 0.8 mg/L. It has shown a strong correlation with postoperative complications, namely after abdominal surgery. In addition, due to its short half-life (19 hours), plasma CRP is a reliable marker of SIRS secondary to surgery since it increases in response to surgical injury for up to 72 hours, decreasing afterward. Serum CRP is the most widely studied biomarker for CAL diagnosis. In patients with postoperative complications, CRP levels remain high. Plasma CRP higher than 140 mg/L on POD3 is a strong predictor of major abdominal septic complications [134].
