Does transanal drainage tubes placement have an impact on the incidence of anastomotic leakage after rectal cancer surgery? a systematic review and meta-analysis

Colorectal cancer (CRC) is the most common malignancy of the digestive tract, with the third highest incidence of all malignancies worldwide and the second leading cause of cancer death [1].The incidence of rectal cancer (RC) in China has been on the rise [2]. As part of a comprehensive treatment, RC is currently treated with surgery. Due to the rapid development of Total Neoadjuvant Therapy (TNT), the multimodal approach in the treatment of rectal cancer and various anastomosis and reconstruction techniques in recent years, the treatment of RC with colorectal surgery has made great progress and the incidence of postoperative complications and dysfunction was also significantly reduced in some patients [3]. Nevertheless, anastomotic leakage (AL), a serious complication, remained prevalent [4, 5].

Patients with AL have a poor prognosis, lengthy treatment times, and immense economic and psychological burdens, as well as complications such as peritonitis and sepsis [6].The occurrence of AL will also contribute to a higher local recurrence rate and a lower survival rate [7]. The factors influencing AL are not entirely clear at present. Several studies have shown that TDTs placement after the surgery of RC can reduce the risk of AL [6, 8, 9] or Grade C AL [10], but some studies have shown different results. The placement of TDTs can replace the effect of enterostomy in protecting the anastomosis and avoiding the reoperation, according to some researchers [11]. However, some researchers believe that TDTs placement will not reduce the occurrence of AL but may also cause anastomotic bleeding and intestinal perforation due to mechanical stimulation [6]. Therefore, through a systematic review and meta-analysis of TDTs placement and AL after RC surgery in prospective studies, this study further clarified the internal relationship between them, aiming to provide theoretical references for clinical practice.

Currently, a variety of adjuvant therapy techniques and anastomosis methods are used to treat RC, which results in a higher rate of Sphincter Preserve. However, the incidence of AL after RC surgery is still at a high level. Therefore, a clear understanding of the risk factors and protective factors of AL can bring great benefits to patients. The TDTs is used to drain the proximal intestinal contents and reduce the stimulation of the anastomoses. It can reduce intestinal cavity pressure and the tension of anastomoses. However, there is no consensus on whether the placement of TDTs can reduce the occurrence of AL.

AL following RC surgery cannot be reduced with the placement of TDTs, according to 7 prospective studies in this study. At the level of the original study, according to Tumura [16] and Zhao [4] there was no statistical significance between the placement of TDTs and AL, which is consistent with our findings. Meanwhile, the study of Xiao [9] and Zhao [13] demonstrated that TDTs placement was a protective factor for AL. Additionally, meta-analyses of the placement of TDTs and AL after RC surgery have had inconsistent results. A meta-analysis of Deng [20] found that TDTs placement reduced AL incidence in low-risk patients (OR = 0.29, 95%CI = 0.13–0.63, P = 0.002), but not in high-risk patients undergoing neoadjuvant treatment. The meta-analysis conducted by Zhao [10]found no significant association between the placement of TDTs and the prevalence of AL. However, it did reveal a reduction in the occurrence of Grade C AL (RR = 0.33, 95%CI = 0.11–1.01, P = 0.05). The discrepancies in the results between Deng [20], Zhao [10], and this study may be attributed to the inclusion of different types of studies and Differences in sample size. Deng [20] included both prospective and retrospective studies, this study included prospective studies, and Zhao [10] only included randomized controlled trials. In Guo's [21] subgroup analysis of the meta-analysis, it was determined that TDTs placement did not exhibit a significant association with the low incidence of AL in randomized controlled trials. However, in observational studies, there was a notable association between TDTs placement and the occurrence of low AL. This finding underscores the influence of study design on the obtained results. Among the seven original papers included by Deng [20] it is noteworthy that only three of them were prospective studies. Consequently, the divergent conclusion reached by Deng's [20] study in comparison to the present study can plausibly be attributed to the heterogeneity of results arising from the inclusion of distinct study types. This study exhibits a degree of resemblances to the studies conducted by Deng [20] and Zhao [10]. Nevertheless, Deng's [20] research primarily centers on retrospective studies. The limited evidentiary value of retrospective cohort studies hinders the broad applicability of their findings. Despite the inclusion of the most rigorous randomized controlled trials in Zhao's [10] study, it was relying solely on three primary research papers. In contrast, this study incorporated seven prospective studies. In comparison to Deng's [20] study, the prospective studies integrated into this study entail rigorous data quality control during case screening. This practice serves to mitigate the bias arising from case–control studies to a certain degree, thereby enhancing the reliability of the findings. Furthermore, it encompassed a greater volume of original literature and a larger sample size than Zhao’s [10] study. As a result, this study provides a higher level of evidence and relatively more reliable outcomes.

AL was categorized into one of three grades (Grade A, B, or C) based on its influence on clinical management [12]. Presently, there is a consensus within the academic community regarding the placement of TDTs to alleviate the severity of AL. When AL ensues, the anal sphincter frequently persists in contracting because of inflammation, pain, and other causative factors. Furthermore, AL frequently manifests during the initial postoperative phase, when the intestinal function has not been restored, and the intestinal contents cannot be eliminated in time, resulting in intestinal high pressure. Physical stimulation caused by high pressure in the intestinal cavity and chemical stimulation caused by intestinal contents is not conducive to the healing of the AL. Drainage of intestinal contents by placing TDTs reduces pressure in the lumen and promotes fecal excretion [9, 22], thus promoting recovery of AL. The findings of this meta-analysis indicate that there is no significant correlation between TDTs placement and a reduced occurrence of AL following RC surgery (RR = 0.89, 95%CI 0.57–1.37, P = 0.58). Considering the following three factors, the relationship between TDTs placement and the incidence of different grades AL was analyzed: (1) Distinct grades of AL necessitate distinct clinical management principles, (2) Grade C AL is of significant concern, as it necessitates a subsequent surgical intervention and escalates the likelihood of restomy and other postoperative complications, (3) TDTs placement can reduce the severity of AL. Given that only four studies in the original literature included recorded the detailed incidence of AL across all levels, it is noteworthy that two out of these four studies did not document the occurrence of Grade A AL. As a result, the present study directed its analysis towards Grade B AL and Grade C AL, while excluding Grade A AL from consideration. The findings of this research indicate that the implementation of TDTs does not result in a decrease in the occurrence of Grade B AL or Grade C AL. Based on the analysis of data from three randomized controlled trials, Zhao’s study determined that the p-value for the association between TDTs placement and the occurrence of Grade C AL was 0.05. Consequently, the researchers of the study of Zhao [10] reached the determination that the placement of TDTs could potentially yield positive outcomes in mitigating Grade C AL. However, Zhao’s [10]study did not yield any statistically significant association between the placement of TDTs and the mitigation of Grade B AL. This research group holds a dissenting perspective on the notion that the implementation of TDTs is incapable of diminishing the occurrence of minor Grade B AL, yet it can effectively mitigate the prevalence of severe Grade C AL, while nor does Zhao’s [10] article offer an explanation for the possible underlying mechanism. As a result, this study augmented the sample size and arrived at an alternative conclusion, namely, the placement of TDTs does not exhibit no correlation with the low occurrence of Grade C AL. This finding suggests that while the placement of TDTs may mitigate the severity of AL, it does not have a significant impact on the occurrence rate of AL.

Furthermore, the present study revealed that the placement of TDTs did not result in a higher occurrence of postoperative complications, including anastomotic bleeding, incision infection, and anastomotic stenosis. The drainage of TDTs, to a certain extent, can support the anastomotic stoma and can be used to detect complications such as anastomotic bleeding and anastomotic infection early, which allows clinicians to take action timely. By using anoscopes and other instruments under direct vision, at the same time, TDTs with moderate hardness was selected, which can minimize the injury of the anastomosis. TDTs of appropriate size and hardness will not cause injury and bleeding of anastomosis. Hence, in cases of AL, the placement of an economical, efficient, and secure TDTs can be employed as a measure to mitigate the extent of AL.

Positive results were observed exclusively in subgroup analysis conducted on area, revealing that TDTs placement served as a protective factor for AL in the Asian group, whereas it posed a risk in the European group. This outcome could potentially be attributed to variations in the study's sample size, discrepancies in the assessment of AL, and the utilization of diverse types of TDTs.

Several factors contribute to AL, and more studies are being conducted to determine the causes and development of AL. It has been confirmed that some factors are closely related to AL's development, such as albumin levels lower than 4 g/dL [23] and operation time longer than 3 h [5]. As a common clinical treatment, the placement of TDTs has low technical requirements and is suitable for hospitals of every level. Multiple studies have documented the occurrence of unfavorable incidents associated with the placement of TDTs subsequent to RC surgery, with anal pain being the most frequently reported complication [4]. Due to the lack of comprehensive documentation regarding adverse events following TDTs placement in the original literature included in this meta-analysis, statistical analysis pertaining to such events was not performed in this study. The visual analogue scale was employed to assess the pain perception experienced by the patients, which is also suitable for the assessment of anal pain after the placement of TDTs. The score ranges from 0 to 10, where 0 denotes the absence of pain and 10 signifies the most severe pain that can be imagined [24]. The pain was subsequently categorized into four distinct levels. No pain: score of 0, indicating the absence of pain; Mild pain: score of 1–3, representing pain that is tolerable; Moderate pain: score of 4–6, indicating pain that may disrupt sleep but remains tolerable; Severe pain: score of 7–10, signifying pain that is unbearable. A randomized controlled study found that TDTs placement caused anal pain in 46.4% of patients, moderate pain in 3.9%, and unbearable pain in 3 patients [4]. What's more, other studies have documented iatrogenic perforation resulting from the placement of TDTs [6, 25], as well as cases necessitating emergency laparotomy due to such perforations [25]. In addition, studies have reported that no expected drainage effect occurs after the placement of TDTs, manifested as fecal discharge from the anus rather than from the TDTs [4].Despite the lack of correlation between the placement of TDTs and the occurrence of AL after RC surgery. However, it is considered that the placement of TDTs can reduce the severity of AL, and healthcare professionals can enhance patient outcomes by proactively optimizing preoperative nutrition, limiting surgical duration to a maximum of three hours, and implementing the placement of TDTs following AL. The placement of TDTs helps to discharge the intestinal contents in time, which is conducive to reducing the length of hospital stay. Studies have found that patients with high-risk factors for anastomotic leakage, such as diabetes and open surgery, have a higher probability of readmissions within 30 days [26]. The placement of TDTs positively affects the timely and rapid detection of intestinal abnormalities. Thus, the disease can be treated earlier and the reoperation rate can be reduced.

There are several strengths of this meta-analysis: All relevant prospective studies (n = 7) from recent years with rich data and high statistical power were included. In addition, our study included recently published randomized controlled trials and more participants (n = 1774) than previous meta-analyses. Finally, a sensitivity analysis was performed to assess the potential influence of utilizing adjusted risk ratios on the aggregated effect estimates.

There remain certain limitations within this study. Primarily, the present meta-analyses were unable to mitigate heterogeneity, whether in the overall population or in subgroup analyses. Furthermore, while gender and age are commonly recognized as confounding factors in numerous studies, there exist additional variables that may also hold significant importance, such as the type of TDTs, presence of diverting stoma, and utilization of Neoadjuvant therapy, which may also possess considerable significance. However, none of these phenomena have been thoroughly investigated. The third aspect pertains to the highly intricate and diverse nature of AL. The existing model is incapable of mitigating this heterogeneity. Fourth, the sample size of some included documents is small, and the statistical impact may exhibit constraints, thereby posing challenges in terms of generalizability of the findings.

In conclusion, the placement of TDTs does not yield significant results in terms of reducing the occurrence of AL after RC surgery, including Grade B AL, and Grade C AL. Furthermore, TDTs placement does not lead to heightened complications such as anastomotic bleeding, incision infection, or anastomotic stenosis. Based on the potential for anal pain, iatrogenic perforation, and limited efficacy associated with TDTs placement, we advise against the immediate placement of TDTs following RC surgery. The findings of this research are derived from a compilation of seven prospective studies. Given the current scarcity of data and the variability observed among studies, the conclusion remains subject to scrutiny. Consequently, future investigations should prioritize the implementation of meticulously planned randomized controlled trials with substantial sample sizes to corroborate this assertion.