Anastomotic leakage is a major complication after lower rectal surgery and is associated with postoperative morbidity, mortality, functional defects, and oncological outcomes [5, 6]. Several risk factors have been reported for anastomotic leakage after open LAR [7-11], and recent studies have also examined the risk factors for anastomotic leakage after laparoscopic LAR [12-21]. The devices and techniques used for laparoscopic LAR differ from those used in open LAR, suggesting that the risk factors for anastomotic leakage also may differ between laparoscopic and open LAR. According to these studies, the anastomotic level, number of linear staples, sex, smoking habits, alcohol intake, previous abdominal surgery, preoperative chemoradiotherapy, tumor location, stage, operative duration, blood loss volume, transfusion, and precompression before firing are reported risk factors for anastomotic leakage after LAR. In the present study, our analysis of potential risk factors suggests that the presence of underlying disease, the use of transanal hand-sewn anastomosis, and the use of closed drains may increase the risk for anastomotic leakage.
In some studies, intraoperative blood loss volume was a reported independent risk factor for anastomotic leakage [17-19, 21, 22]. In the present study, we found no significant association between blood loss volume as a continuous variable and anastomotic leakage. This finding suggests that anastomotic leakage did not occur directly because of bleeding and that intraoperative blood loss volume was likely to be a surrogate for surgical difficulty.
The duration of surgery is a reported risk factor in some studies [23-25]. Our study confirmed that patients with a longer surgical duration had a higher incidence of anastomotic leakage. Prolonged surgery may be caused by lower surgical skill or poor exposure of the surgical field secondary to pelvic stenosis or a large tumor. In addition, decreased blood perfusion caused by prolonged anesthesia may increase the risk of anastomotic leakage.
Previous studies have reported that diabetes mellitus is a risk factor for anastomotic leakage [26, 27], which our results confirmed (Table 3). Possible reasons for this increased risk include the following: insufficient blood supply to the anastomosis secondary to microcirculatory disorders, insufficient glycogen stores, and delayed tissue healing secondary to hyperglycemia. These results suggest that patients with type 2 diabetes mellitus require good blood glucose control before surgery to reduce the risk of anastomotic leakage post-LAR. However, other studies have found that diabetes was not a risk factor for anastomotic leakage [16, 28].
Sánchez-Guillén et al. reported the perioperative risk factors for anastomotic leakage and for 60-day morbidity and mortality after ileocolic anastomosis (stapled vs hand-sewn). The authors’ multivariate analysis showed the following independent risk factors for major anastomotic leak: male sex (P = 0.0140, odds ratio [OR]: 2.9), arterial hypertension (P = 0.0480, OR: 2.29), and perioperative transfusion (P < 0.0010, OR: 2.4 per liter). The overall 60-day complication rate in that study was 27.3%. Male sex (31.3% complication rate vs 22.3% among female patients, P = 0.0200, OR: 1.7), diabetes (P = 0.0300, OR: 2.0), smoking habit (P = 0.0400, OR: 1.8), and perioperative transfusion (P < 0.0010, OR: 3.3 per liter) were independent risk factors for postoperative morbidity . These results are consistent with our underlying disease results, which suggest that the presence of underlying disease is associated with anastomotic leakage.
Several studies have reported that tumor location and distance from the anal verge are risk factors for anastomotic leakage after LAR [13-17, 20]. Choi et al. reported that the anastomotic leakage rate was 10 times higher when the anastomotic region was located within 5 cm of the anal verge in a series of 156 patients who underwent LAR without double stapling . It is hypothesized that tumor location and distance from the anal verge may reflect technical difficulty and affect anastomotic tension and blood supply. In multivariate analysis in the present study, there was a statistically significant difference in leakage occurrence between double-stapling and hand-sewn anastomosis. Therefore, we concluded that these were likely risk factors for anastomotic leakage.
Our results showed that the type of drain was related to anastomotic leakage after LAR. To our knowledge, this result has not been reported previously and is considered an important finding. An open drain can be used for effective long-term drainage, but the possibility of retrograde infection is a concern. In contrast, a closed drain is less likely to be associated with retrograde infection, but obstruction is a problem. Although some reports have described the risk of retrograde infection in patients with open drainage [30-32], none has reported the related frequency or any diagnostic criteria. In the present study, no retrograde infection occurred in patients with open drainage. A peritoneal defect is sometimes present within the pelvis after rectal resection. This loss of peritoneum decreases reabsorption of effusion and increases the risk of infection, predisposing to abscess formation. There is a strong possibility that these conditions lead to leakage.
Because efficient fluid drainage is important, we consider it necessary to carefully consider which type of drain to use in digestive surgery. Surprisingly, in the propensity-score analysis, patients with closed drainage had a 6.315 times higher risk of postoperative leakage than those with open drainage. This finding is impressive and important, and statistically meaningful.
The limitations of this study must be addressed. The major limitations are the single-institution, retrospective design and the small number of patients. In fact, the rate of anastomotic leakage in this study was slightly higher (21.7%) than that in other studies. This higher percentage may be attributed to the fact that many of the patients in this study had advanced disease. Moreover, many patients had Rb-positive lesions, which may have caused selection bias. Additionally, we excluded patients who received preoperative chemotherapy or chemoradiotherapy because of our department’s treatment policy.
These limitations should be considered when evaluating the results of our study. A prospective study involving multiple institutions with a unified definition of anastomotic leakage and standardized procedures is needed. However, to our knowledge, no studies have collected and analyzed drainage data in patients undergoing lower rectal surgery; therefore, our findings are noteworthy.