*Colorectal Anastomosis: The Critical Aspect of Any Colorectal Surgery DOI: http://dx.doi.org/10.5772/intechopen.107952*

non-absorbable antibiotics are advocated despite increasing evidence challenging its benefits. For example, intestinal preparation reduces fecal bulk, clears the bowel lumen, and reduces bacterial colonization, decreasing postoperative complications risks such as anastomotic dehiscence and wound infection. In addition, oral nonabsorbable antibiotics decrease intraluminal bacterial content after mechanical bowel preparation. On the other hand, MBP detractors oppose that MBP has complications, such as clinically significant dehydration and electrolyte disturbances in the preoperative period, and the process is both time-consuming and unpleasant for patients. Therefore, they said the clinical practice sustains that oral and intravenous prophylactic antibiotics are sufficient because the evidence has shown that the gut microbial flora load is not reduced grossly by bowel preparation.

These two main currents of opinion may contribute to implementing different ERAS programs: ERAS pathways in the UK and European guidelines do not include MBP/oral antibiotics. In contradiction to the UK and Europe, North American guidelines recommend incorporating combined mechanical and oral antibiotic bowel preparation into ERAS programs stated [71].

More solid and structured studies are necessary to clarify the real benefits of combined intestinal preparation in colorectal surgery. The published studies are not comparable due to different designs. For example, if MBP is recommended for all colorectal surgery or only in specific situations (left colorectal surgery, anterior rectal resection, or right laparoscopic surgery); if MBP is performed with or without prophylactic oral antibiotic therapy and in case of oral therapy what kind of antibiotics are due and which scheme. On the other hand, some meta-analyses analyzed studies with different features, such as prospective vs. retrospective and randomized vs. not randomized, which do not have the same scientific value. These aspects induce the appearance of difficult-to-interpret biases.

Despite these constraints, in summary, we can read recent papers defending reducing the risk of CAL and surgical site infections with:


In current practice, at least for low anterior resection and laparoscopic right colectomy, MBP plus oral antibiotics seems defensible. Indeed, the higher risk of CAL and its consequences on distal colorectal anastomoses and the more significant contamination with enteric content during laparoscopic anastomosis if intestinal preparation is not performed are valid and essential arguments to consider.

So, this issue remains in debate. The current recommendations for mechanical bowel and oral preparation before colectomy surgery to reduce SSIs or CAL risk should be reconsidered after the realization of well-designed, prospective, and double-blind studies.

#### *7.2.4 Anesthesia technique*

With the development of ERAS protocols, **epidural anesthesia** is commonly used in abdominal surgery to improve pain management and early patient mobility. In addition, epidural anesthesia is essential when the approach is open instead laparoscopic. The initial studies about the utilization of this technique aroused some doubts if it can contribute to a higher risk of CAL.

Recent studies demonstrated that **intraoperative fluid management** in the ERAS programs is not consensual, with limited evidence regarding fluid management protocols. A restrictive vs. liberal fluid regimen seems to benefit pulmonary complications but not the other morbidity [83]. Several studies do not report differences in CAL rate between restricted vs. liberal fluid administration [84, 85]. The National Institute for Health and Care Excellence (NICE) recommended major abdominal surgery by using esophageal Doppler monitoring for individualized fluid management to reduce complications (not necessarily the CAL rate), as shown in the meta-analysis by Walsh et al. [86].

#### *7.2.5 Surgical technique*

**High surgeon experience**, **volume center**, and **operation time** can influence the rate of CAL [30, 87–89]. Operative time longer than 3 hours has also been described in the literature as being associated with an increased incidence of anastomotic dehiscence [68, 90]. **Blood loss** greater than 300 ml with **multiple blood transfusions** or **large fecal contamination** is independent risk factors for CAL [91]. In those cases, it is unclear if they are related to a particular complex procedure or a lack of surgeon experience.

Differences between **open or laparoscopic colorectal approaches** in terms of CAL have not been demonstrated [92, 93]. The COLOR II trial showed statistically significant differences in blood loss, bowel recovery, and the length of hospital stay in favor of the laparoscopic approach and no difference between open and laparoscopic rectal resection in terms of postoperative anastomotic leakage or mortality [94]. Two recent meta-analyses comparing laparoscopic intersphincteric resection vs. an open approach for low rectal cancer have shown no significant difference in anastomotic leakage incidence between the two groups [95, 96]. Nevertheless, the results are contradictory. In anterior rectal resection for rectal cancer, some studies refer to laparoscopic surgery vs. open surgery as a significant factor in decreasing CAL [41].

**Robotic colorectal surgery**, including right and low anterior resection, is safe and feasible but has no clear advantages compared with laparoscopic surgery in terms of postoperative outcomes. The rate of anastomotic leakage was comparable between the two techniques [97, 98].

#### *Colorectal Anastomosis: The Critical Aspect of Any Colorectal Surgery DOI: http://dx.doi.org/10.5772/intechopen.107952*

There are **general rules of surgical procedures** that must be fulfilled to contribute to achieving in colorectal surgery, a low rate of CAL. First, independent colorectal type procedure, the surgical technique must be standardized with careful and meticulous dissection. **Avoid anastomosis** tension is one of the general principles to follow during anastomosis confection. In a German expert meeting, a three-step Delphi method was used to find consensus recommendations for how to reduce anastomotic leakage in colorectal surgery. There was a strong consensus in regard to routinely mobilizing the splenic flexure and dividing the inferior mesenteric vein as the main technical aspects to avoid anastomosis tension [99]. **Proper vascularization of intestinal segments** involved in an anastomosis is a primordial factor that can determine healing on the digestive suture. In anterior rectal resection preservation of the left colic artery is an independent factor for anastomotic leakage in laparoscopic rectal cancer surgery according to the studies made by Yao et al. [30] and also by Trencheva et al. [39]. Intraoperative endoscopic visualization can detect anastomotic insufficiency. This procedure can be routinely performed in colorectal anastomosis reducing CAL probability. Recently, the measurement of microcirculation has gained substantial interest. **Indocyanine green (ICG) fluorescence angiography** is a new technique that helps surgeons to assess the blood perfusion of the colon in anastomosis. The meta-analysis and systematic review realized by Li et al. and by Liu et al. agree that ICG fluorescence angiography reduced the CAL rate after colorectal anastomoses for rectal cancer patients. However, both authors considered that more high-quality randomized controlled trials are needed to confirm this benefit [100, 101].

When considering the surgical technique in left colorectal surgery, studies have failed to show significant CAL rate differences between **handsewn or stapled anastomoses** [102]. The considerations about stapled vs. handsewn colorectal/coloanal anastomoses for CAL risk [103] differ from ileocolic anastomoses. In the last one making stapled anastomoses seems safer with minor CAL risk [104, 105].

In ileocolic anastomosis, stapled has less risk of leakage than hand-sewn. It seems that stapled functional end-to-end ileocolic anastomosis is associated with fewer leaks than handsewn anastomosis [105]. In colorectal anastomosis the panorama is different. In stapled anastomosis is necessaire linear stapler for transecting the rectum and a circular suturing machine for the anastomosis. A systematic review and metaanalysis realized by Balciscueta et al. confirm the impact of the number of stapler firings on anastomotic leakage in laparoscopic rectal surgery [106].

During the surgery, an effort must be made to reduce the **number of linear stapler firings** and try to transect the rectum with a single fire. Several studies corroborate the importance of this technical procedure step [107, 108].

The **powered circular stapler device (ECPS)** could have a positive impact by reducing AL rates in left-sided colorectal anastomosis [109].

During left colorectal surgery, immediately following anastomosis, surgeons evaluate **anastomotic integrity** through assessment of anastomotic doughnut completeness, air leak testing, methylene blue testing or povidone-iodine testing, and/or endoscopic visualization with to reduce rate CAL. The most frequent test used is the air leak test which is considered as an important test during an anterior rectal resection for the majority of surgeons that collaborate in international meeting consensus [99]. **Intra-operative endoscopy** can be performed allowing the surgeon to assess for vascular insufficiency and staple line bleeding.

Making a **protective stoma** (ileostomy or colostomy) after low anterior resection remains debatable. The most commonly used form of stoma is the defunctioning loop ileostomy, but some surgeons advocate the use of loop colostomies. The meta-analysis made by Chen et al. and Rondelli et al. shows that temporary loop ileostomy when compared with temporary loop colostomy had a lower risk of prolapse and sepsis [110, 111]. Nonetheless, loop ileostomy has a risk of dehydration and occlusion after stoma closure [111].

The effect of a diverting stoma in this procedure is generally considered a reducer of CAL (mitigates the clinical effects of fistula), but there are studies demonstrating diverting stoma as an element to reduce CAL probability. In surgery for distal rectal cancer, Matthiessen et al. demonstrated, in a cohort of 234 patients a symptomatic leak rate of 10·3% and a significantly lower reoperation rate in the defunctioned group (ileostomy or colostomy), compared with 28% in the non-stoma group [112]. Similar results were obtained in a prospective randomized study by Chude et al. which demonstrated significantly reduced CAL rates in the group with a defunctioning ileostomy (2·3 vs. 9·3%); no patient in the ileostomy group required surgical intervention or died [113].

#### *7.2.6 Peri and postoperative therapy*

**Hypothermia** increases the risk of surgical-site infections and induces vasoconstriction, but there is no conclusive evidence that it is a risk factor for AL.

The **use of inotropes** is associated with a three-fold increase in AL; this risk is accentuated by the use of multiple agents and the duration of inotropic support. This risk is independent of medical status as determined by Acute Physiology And Chronic Health Evaluation (APACHE) II and Physiological and Operative Severity Score for Mortality and morbidity (POSSUM) physiological scoring systems.

The need of **blood transfusion** is also an independent risk factor for CAL as already asserted. During the surgery, the need of inotropes or blood transfusion are factors that by themselves, advise the creation of a diverting stoma or avoid the anastomosis confection.

Perioperative analgesia with **non-steroidal anti-inflammatory drugs (NSAIDs)** has controversial aspects. During the inflammatory process necessary for healing anastomotic, the enterocytes express high levels of cyclooxygenase 2 (COX-2) with the formation of E2 prostaglandins, responsible for increasing vascularization place, promoting the expression of the factor of endothelial growth and angiogenesis. Thus, some authors defend a direct association link between anastomotic leak and the anti-inflammatory effect of NSAIDs [114]. Because the greater expression of COX at the intestinal mucosa level is COX-1, theoretically, selective NSAIDs for COX-2 (celecoxib, parecoxib) could be less harmful to intestinal anastomotic healing than non-selective NSAIDs (diclofenac, ketorolac). However, there are no studies yet demonstrating unequivocally different CAL risks within classes of AINS, and even the higher risk associated with using NSAID during perioperative time is still controversial. A study by Burton et al. evaluated perioperative non-steroidal anti-inflammatory drugs (NSAIDs) used in colorectal resections and found no statistically significant effect on the CAL rate [115]. The meta-analysis "PROSPERO" realized by Chen et al. indicates that using ketorolac increases the risk of CAL [116]. Also, the study by Klein et al. established an increased CAL risk in colorectal surgery with the postoperative use of diclofenac. Gorissen et al. noted a significant association of a higher CAL rate with NSAIDs, mainly non-selective NSAIDs [117]. Holte et al. describe the risk of CAL augmentation in colorectal surgery even using celecoxib [118]. In conclusion, NSAID treatment could increase the proportion of patients with anastomotic leakage after colorectal surgery. Therefore, even Cyclo-oxygenase-2 selective NSAID should

be cautiously used after colorectal resections [119]. Large-scale, randomized controlled trials are needed to clarify this issue.

**Implementing an Enhanced Recovery After Surgery (ERAS) program** in elective colorectal surgery reduces hospital stay and surgical morbidity. ERAS programs for colorectal surgery have significant variations in care between institutions. As already discussed, some differences, including perioperative analgesia and intestinal preparation, can interfere with the CAL rate.

Nonsteroidal anti-inflammatory drugs are a crucial component of contemporary perioperative analgesia in the ERAS program. They can avoid the side effects associated with opioids (postoperative ileus, urinary retention, change in consciousness, and central respiratory depression), contributing to the early mobilization of patients [120]. Despite its advantages, the set of reactions and adverse effects associated with NSAIDs, namely in the gastrointestinal tract (such as bleeding, nausea, vomiting, and ulceration) and the eventual increase of CAL rate in colorectal surgery, are not despicable [121]. Cyclo-oxygenase-2 selective NSAID utilization for a short period may be the best analgesic option if the ERAS program includes the use of NSAIDs.

The utilization of mechanical intestinal preparation with oral antibiotics in the ERAS program for colorectal surgery does not happen in wall programs. Therefore, implementing this procedure can reduce the benefits of enhanced recovery after the surgery program but eventually may reduce CAL risk, as already stated.
