Postoperative anastomotic leakage (PAL) is the most common complication of gastric cancer surgery, affecting 2.1–14.6% of all patients (16–19). PAL is regarded as one of the most serious complications and is consistently associated with high postoperative mortality rates, reaching as high as 60% in some studies (20, 21). PAL can be regarded as one of the key indicators of surgical quality, since it is related to the level of expertise of the surgeon(22). PAL has also had a significant impact on several other postoperative outcomes (23).
Whether the use of IOLT in gastrectomy can significantly reduce PAL rate is yet to be decided. IOLT involves injecting air and methylene blue into the anastomosis, which can help observe the integrity of the anastomosis directly. Any defects in the anastomosis can be repaired during surgery. Katsunori Nishikawa was the first to test the efficacy of IOLT in gastric cancer surgery. Previous single center, small sample studies demonstrated that IOLT can detect anastomotic leakage and allow for the repair of the defects and thus a reduction in PAL rates (24). However, some researchers insist that IOLT has no place in bariatric surgery since they found that IOLT does not reduce postoperative complications (25, 26). Some other disadvantages are IOLT prolonged operation time and increased resource utilization. Some researchers found that IOLT cannot prevent all anastomotic leakage, such as late leakage and leakage caused by other factors, such as poor surgical technique or the age of the patient(10, 15). Therefore, the preventive effect of IOLT on postoperative complications remainsto be further studied.
PAL may lead to serious complications, including hemodynamic instability, sepsis, multi-organ failure, and even death(27). This study comprehensively evaluated the efficacy of IOLT as measured by PAL and other postoperative complications. Through retrospective analysis and meta-analysis of relevant articles, our research found that IOLT can reduce the incidence of PAL (moderate quality evidence), anastomotic-related complications (moderate quality evidence), and reoperation rates (moderate quality evidence) for gastric cancer surgery. According to the Cochrane manual, publication bias testing is required for more than 10 articles included in a meta-analysis. As such, bias testing was not performed in this study. When determining the overall quality of evidence, we assumed that there was no publication bias between overall evidences on the basis of the risk of bias in a single study and the degree to that each study contributed to the estimated effect (28).
In this study, we found that PAL rates were lower in the IOLT group than the NIOLT group. Z Wu, et al found that the PAL rate was 4.8% in the IOLT group compared to 6.1% in the NIOLT group. This result suggests that IOLT did not significantly reduce PAL rates after colorectal surgery in this meta-analysis. The lack of statistically significant difference may be due to the fact that one study is substantially influencing the sensitivity analysis of the meta-analysis (6). A randomized controlled trial with small sample size found that intraoperative endoscopy could prevent technical defect-related leaks in laparoscopic Roux-en-Y gastric bypass bariatric surgery(29). The significance of our study is that IOLT not only has a preventive effect on PAL, but can also significantly reduce other postoperative complications, such as postoperative anastomotic-related complications and reoperation rates in gastric surgery.
The technique of IOLT has been applied in various ways in clinical practice, although there is no consensus on the standardization of IOLT. According to published articles on IOLT for gastric cancer surgery, bariatric surgery, colorectal surgery and our own experience, we found that IOLT can be performed by gastroscopy or gastric tubes. Interestingly, researchers found that IOLT performed with gastroscopy had statistically significant lower PAL rates than IOLT performed with gastric tubes had (30, 31). When compared with IOLT using gastric tubes, intraoperative gastroscopy had the advantage of detecting and preventing severe complications such as esophageal perforation. However, a gastric tube maybe a viable option for IOLT when there is no gastroscopy device or professional endoscopists available. The method of intraoperative leakage test has not been unified. Some scholars use the air testing(32) while another scholars use the methylene blue testing(11). Which method is better is currently the controversial point. We recommend the combination of air testing and methylene blue testing(31).
Intraoperative air pressure plays a crucial role in the process of IOLT. Biomechanically, standardizing the volume of injected liquid or air can be difficult due to the complexity of the human anatomy. It is important to keep the anastomotic pressure within a safe range to avoid excessive perfusion pressure or anastomotic bursting pressure. Excessive perfusion pressure can lead to insufficient blood perfusion, inadequate oxygen supply, and an increased risk of postoperative obstruction, dyspnea, and anastomotic rupture(23). The anastomotic blasting pressure wascarried out in animals and in vitro experiments (33–35). One experimental study showed that the colorectal anastomosis can be ruptured at 70–184 mmHg pressure, which demonstrates that there was a risk of rupture when 400ml liquid was injected (35). Anastomotic pressure monitoring is thus recommended for IOLT. Further studies are needed for finding safe pressures in IOLT.
There are three limitations of our study. The first limitation is that only 3 observational studies were included in this meta-analysis since IOLT is not widely used in gastric cancer. Second, the quality of overall evidences was not high. Lastly, the ways of IOLT were not uniform. This may be a confounding factor.