**1.1 Importance of colorectal anastomosis in colorectal surgery and anastomotic leakage implications**

Most colorectal surgery implies intestinal resection and, if possible, bowel continuity restoration. Conceptually, colorectal resection surgery without reconstitution of intestinal continuity is a functional surgery not entirely achieved. The patient and the surgeon aim to avoid a permanent stoma after any bowel resection surgery. The reconstitution step is, therefore, the critical point for any colorectal surgery. The surgery may have been perfect from the point of view of surgical technique. However, if any problems arise at the level of the anastomosis, the surgical results obtained will be compromised temporarily or permanently, with a spectrum of variable severity. In fact, the presence of some leak in the anastomosis may have, in addition to short- and

medium-term infectious implications, functional and survival implications, in the latter case in oncological patients.

In this perspective, it is essential to define and standardize the concept of colorectal anastomotic leakage (CAL), as well as know its etiopathogenesis, the possible occurrence promotor factors, how to detect it early and, if present, how to manage and reduce its consequences.

This chapter intends to analyze and reflect on these aspects and, in this way, prevent and reduce the occurrence of anastomotic leaks and, if it happens, minimize their consequences and settle the issue.
