PA assesses the blood ow to the tissue but does not consider other factors that might play a causal role in the occurrence of AL.Surgeon prediction of AL is not reliable [40]. It seems plausible that patient factors (nutritional status, previous chemoradiotherapy, frailty) and technical aspects play an important role in AL [41]. Recently, dys­biosis and the impact of the microbiome in anas­tomotic integrity have been pursued in mechanistic studies. Surgery represents a major physiological stress, and postsurgical recovery is not fully understood. Recent evidence has shown that the preoperative bowel preparation, prophy­lactic antibiotics and surgical trauma have a sig­nicant impact in the microbiological environment at the anastomosis. The extent to which these factors shape the microbiome has not been completely elucidated [42]. This may lead to a disproportionate increase in bacteria with a more virulent phenotype [41]. The absence of the normal bacteria may favour the occurrence of disseminated infection and sepsis, AL or superin­fection (e.g. C.Difcile). Preclinical models have suggested that inamed and injured intestinal tis­sues undergoing repair select strains of bacteria that express a high collagenase-producing pheno­type which contributes to anastomotic leak [43]. The culture-based methods have been replaced by RNA sequencing and transcriptomic analysis that expands the ability to study the microbio­logical environment [42]. Therefore, there is great potential to explore the microbiome to improve health and prevent AL, as this becomes a more developed area of research.