Risk assessment of rectal anastomotic leakage (RAREAL) after DIXON in non-emergency patients with rectal cancer

We retrieved the electronic medical records of the Second Affiliated Hospital of Fujian Medical University between January 2015 and December 2020, and selected the information of 721 hospitalized patients who had undergone Dixon surgery for rectal cancer who were hospitalized during this period. Exclusion criteria: patients with intestinal obstruction (47 cases), patients with rectal perforation (6 cases), patients with distant metastasis (38 cases), patients with incomplete hospitalization data (26 cases), and patients with prophylactic diverting stoma (131 cases). A total of 473 consecutive patients who had undergone DIXON for rectal cancer were screened and collected. Signed informed consent was obtained from all study subjects. This study was approved by the ethics committee of the Second Affiliated Hospital of Fujian Medical University (2,022,208).

A total of 323 hospitalized patients who underwent Dixon surgery for rectal cancer from January 2015 to December 2018 were used as the modeling group, which were divided into NAL group (297 patients) and AL group (26 patients) according to whether AL occurred after surgery. A total of 150 hospitalized patients who underwent DIXON surgery for rectal cancer from January 2019 to December 2020 were selected as the validation group, including the NAL group (135 cases) and the AL group (15 cases) (Fig. 1).

The investigated variables were age, gender, smoking, Alcohol excess, body mass index (BMI), Previous history of malignancy, hypertension, preoperative chemoradiotherapy (PCT), diabetes mellitus, HbA1c (glycated hemoglobin), American Society of Anesthesiologists physical status classification (ASA ), operation time, intraoperative blood loss, left colic artery (LCA) preservation, tumor distance from the anal margin (TD), number of staples, surgical approach, pathological T stage, pathological N stage, TNM stage, and tumor histological differentiation.

Each patient underwent bowel preparation by oral polyethylene glycol electrolyte solution combined with prophylactic oral enteric antibiotics on the first preoperative day. All surgeries were performed by experienced and skilled colorectal surgeons. According to the criteria of the learning curve of laparoscopic colorectal cancer resection, after 40 laparoscopic colorectal cancer surgeries were carried out, the operating technique of the operating surgeon could achieve a degree of comparative stability [5, 6]. We considered surgeons who carry out more than 40 laparoscopic colorectal cancer procedures to be experienced and skilled colorectal surgeons. The principles of total mesorectal excision (TME) were strictly followed for both open and laparoscopic procedures. For transection and anastomosis of the rectum, linear cutting closure device was used for rectal resection, and circular stapler was used for rectal anastomosis. In each patient with an anastomosis for rectal resection, an ECHELON linear cut closure device was used for rectal resections, and an Ethicon Endo-surgery circular stapler was used for rectal anastomoses. The circular stapler was a double-rows. In recent years, intraoperative indocyanine green (ICG) angiography has been introduced into clinical practice to provide useful information on intraoperative vascular perfusion. However, according to some studies, it does not significantly reduce anastomotic leakage rates [7, 8]. There are still some drawbacks to the technique of intraoperative ICG angiography evaluation. One drawback is the optimal dosage and timing of ICG prior to evaluation. The vascular system has a fast washout time, and an accurate injection protocol is still to be discovered. Another drawback is the lack of strict analysis methods to objectively quantify signal intensity, and the evaluation of images still depends on the surgeon’s judgment. It is currently unclear what precise blood flow rate is required to ensure satisfactory healing of intestinal tissues [7]. Intraoperative air leak test (ALT) is a widely accepted measure to prevent AL [9, 10]. After anastomosis, the ALT was performed on all patients. When the leak test was positive, the anastomosis was repaired by suturing until a negative result was obtained. After anastomosis, the pelvic cavity and abdominal cavity were irrigated with a large amount of distilled water to clean, and a rubber drain was routinely left in place next to the rectal anastomosis in the pelvic cavity.

A multidisciplinary team (MDT) of physicians with independent diagnostic and therapeutic capabilities, mainly from colorectal surgery and anesthesiology departments, including cardiovascular medicine, respiratory medicine, endocrinology, neurology, hematology, Nephrology, nutrition and other related clinical departments, was established. Each rectal cancer patient was consulted by the MDT team. If the patient had diseases for which no preoperative normative treatment has been administered such as: severe hypertension, arrhythmia, bronchial asthma attack, severe chronic bronchitis, acute exacerbation of emphysema, pneumonia, poorly controlled severe hyperglycemia, severe thyroid dysfunction, brain dysfunction, uncontrolled coagulopathy, severe anemia, severe electrolyte imbalance, malnutrition, psychological disorders, and so on, the MDT team would administer optimized treatments to the patient, and then the patient would undergo surgical treatments at a limited period. All patients received adequate nutrition, anti-infection and other symptomatic treatment after operation.

Clinical diagnostic criteria for AL [11]: clinical signs of AL were considered if the pelvic drain was draining pus or stool and there were suspicious symptoms of peritonitis, including abdominal pain, tenderness, fever, tachycardia, or severe inflammation on blood tests. AL was further confirmed by CT scan or colonoscopy. Positive CT scan: abscess and effusion or air bubbles around the anastomosis; Positive colonoscopy: the rectal cavity communicates with the extracavity (Fig. 2). Enema with contrast agent was not routinely performed in our department, and asymptomatic AL was not considered. All rectal cancers were confirmed as primary rectal adenocarcinomas by preoperative colonoscopy as well as postoperative pathology.

Statistical analysis was performed using SPSS 21.0 software. Normally distributed measurement data are represented by \(\stackrel{-}{x}\pm s\), and skewed distribution data are represented by median (first and third quartiles) [M (P25, P75)]. Enumeration data were expressed as the number of cases (%). The t test, χ²test and Mann-Whitney U test were used for statistical analysis of the two groups of data in the NAL group and the AL group. Multivariable Logistic regression analysis was used to obtain the risk factors of the AL group, and the partial regression coefficient was rounded into the score of the corresponding risk factor index. Risk assessment of rectal anastomotic leak (RAREAL) score was used to express the risk of AL group. The area under the curve (AUC) of the receiver operating characteristic (ROC) and the Youden index were used to evaluate the RAREAL score. The maximum Youden index obtained corresponds to the sensitivity and specificity of RAREAL. The RAREAL score was performed on the patients in the modeling group, the ROC curve was used for analysis, and the Z test was used to evaluate the consistency of the ROC curve between the modeling group and the validation group. P<0.05 was considered to be statistically significant.