Analysis of Prevention and Treatment of Anastomotic Leakage after Sphincter-Preserving Surgery for Middle- and Low-Grade Rectal Cancer under Laparoscopy

Background Anastomotic leakage is one of the most serious complications that can occur after laparoscopic-assistedsphincter-preserving surgery for middle- and low-grade rectal cancer. Objectives To explore the cause, prevention, and treatment of anastomotic leakage after sphincter-preserving surgery for middle- and low-grade rectal cancer under laparoscopy. Methods The clinical data from patients with mid- and low-grade rectal cancer who underwent laparoscopic-assistedanus-preserving surgery in the anorectal surgery department of our hospital have been analyzed. Patients with a definite diagnosis, indications for laparoscopic surgery, and sphincter-preserving surgery were included in the analysis, and patients with a protective loop ileostomy and laparotomy were excluded. Results Among the 126 patients with middle- and low-grade rectal cancer undergoing sphincter-preserving surgery under laparoscopy. There were 75 male patients and 51 female patients, ranging in age from 37 to 89 years old, with an average age of 60.2 ± 6.7. The distance from the lower edge of the rectal tumor to the anal edge was ≤10 cm. 6 developed anastomotic leakage after the operation (leakage rate of 4.7%). Moreover, turbid purulent fluid was drained from the abdominal drainage tube in three patients on the third and fourth days after the operation, and the abdominal drainage tube drained serous drainage in three more patients on the fifth and sixth days, with signs of peritonitis appearing locally. All patients received continuous flushing and negative pressure drainage with a self-made double cannula and symptomatic treatment, and all were cured and discharged. Conclusion Many factors can cause anastomotic leakage after this operation, and adequate perioperative preparation, meticulous operation during surgery, and careful postoperative management are key factors in preventing it.


Introduction
Compared with Westerners, the prevalence of rectal cancer in Chinese people has the following characteristics. Its incidence is higher than that of colon cancer, accounting for approximately 60%, and the proportion of middle-and low-grade rectal cancer is high, accounting for approximately 60%-70% of rectal cancer cases. Most such cancers can be touched during digital rectal examination [1]. Anastomotic leakage is one of the most serious complications that can occur after laparoscopicassistedsphincter-preserving surgery for middle-and low-grade rectal cancer, with an incidence of 3%-21% after anterior resection for rectal cancer (Dixon) [2,3]. Te main issue with anastomotic leakage is colonic content corrosion of pelvic and sacral tissues, exposed lymphoid tissues, and blood vessels. If treatment is not timely sought, the leakage will seriously afect patients' postoperative recovery and subsequent treatment and may even lead to death. Tis complication has a high mortality [4]. Terefore, preventing and efectively dealing with anastomotic leakage are of great signifcance. Te clinical data from patients with mid-and low-grade rectal cancer who underwent laparoscopic-assistedanus-preserving surgery in the anorectal surgery department of our hospital have been analyzed.

General Information.
Te data of 126 patients with middle-and low-grade rectal cancer who underwent laparoscopic-assistedsphincter-preserving surgery in the anorectal surgery department of our hospital from June 2017 to December 2020 were retrospectively analyzed. An electronic colonoscopy was performed before the operation for all patients, and rectal cancer was diagnosed via pathology. Tis study was conducted in accordance with the declaration of Helsinki and approved by the Ethics Committee of the Afliated Hospital of Putian University. Written informed consent was obtained from all participants.

Tumor Characteristics.
Preoperative digital examination of the anus, computed tomography (CT), magnetic resonance imaging, and intraoperative exploration were employed in combination. Clinical tumor classifcation: Tere were 74 cases of ulcerative tumors, 32 cases of protruding tumors, and 20 cases of infltrative tumors. Pathological classifcation: Tere were 56 cases of welldiferentiated adenocarcinomas, 45 cases of moderately diferentiated adenocarcinomas, and 25 cases of poorly diferentiated adenocarcinomas. Clinicopathological staging (the tumor-node-metastasis (TNM) staging according to the eighth edition of the Union for International Cancer Control developed in 2017) [5]: Tere were 34 cases at Stage I, 69 cases at Stage II, and 23 cases at Stage III. Te distance from the lower edge of the anastomosis to the anal edge after the anastomosis was >2.5 cm in 51 cases and >4 cm in 75 cases.

Inclusion Criteria.
All patients were informed of the operation plan. Te perioperative preparation was adequate, and no patients had operative contraindications. Laparoscopic-assisted radical resection for middle-and lowgrade rectal cancer (Dixon) was performed for all patients. All patients were anastomosed with double staplers [6]. Patients with a protective loop ileostomy and a laparotomy were excluded. Te operative procedures were approved by the hospital's ethics committee.

Operation
Steps. Each patient was placed in the modifed lithotomy position [7]. Under general anesthesia, after disinfection and surgical drape placement, laparoscopic intraoperative exploration was carried out. After the relationship between the location of the rectal tumor and surrounding organs was basically determined and it was clear that the tumor had not obviously infltrated or metastasized in the abdominal cavity, the uterus of female patients was suspended with purse strings, and an incision was made on the retroperitoneum at the junction of the sigmoid mesocolon and small pelvic cavity with an ultrasonic scalpel. Te inferior mesenteric artery and veins were carefully isolated, clamped, and cut with a ligation latch clip. Te adipose lymphoid tissues around the root of the inferior mesenteric artery and veins were cleaned, and the operation reached the Toldt space to the left to free the sigmoid colon. Following the total mesorectal excision (TME) and nontouch isolation principles, the lymphatic and adipose tissues near the iliac vessels and lateral pelvic wall in the presacral space between the wall and visceral layers of the pelvic fascia were incisively dissected, separated, and removed. An incision of the pelvic foor peritoneum in the rectal bladder or rectal uterine depression was made, and the rectal wall was exposed, approximately 3-5 cm away from the lower edge of the tumor. If necessary, a digital rectal examination was performed during the operation to locate the lower edge of the tumor. Te intestinal canal at the anastomosis was scheduled and clamped with intestinal forceps. Te anus was fully expanded, and the lower rectum was fushed with 250 ml of diluted iodophor and normal saline through the anus to avoid tumor cell contamination in the closed line as far as possible. Ten, the distal end of the rectum was closed with a cutting closure device, the rectum was amputated, and the sigmoid mesosigmoid, and blood vessels were arranged. Te incision of the median one-trocar hole of the lower abdomen was extended 4-5 cm along the transverse line. Te severed rectum and its mesosigmoid were removed from the abdominal cavity, and the sigmoid colon was cut 10 cm from the upper edge of the tumor. Te rectal tumor, sigmoid mesosigmoid and its lymphoid cells, and adipose tissue were removed. Te anvil head of the tubular circular stapler, with a diameter of 29-33 mm, was placed and fxed at the stump of the sigmoid colon. Te abdominal incision was sutured, and the peritoneum was rebuilt. Te stapler handle was inserted into the anus and connected with the anvil head in the abdominal cavity. After confrming that there was no intestinal torsion and that no other tissue was sandwiched in the junction, the anastomosis was started. Te cutting ring in the stapler was checked and sent to the doctor for pathological analysis. After the anastomosis, air was injected into the rectal cavity to check for air leakage, and a self-made double cannula [8] was placed behind and below the presacral anastomosis (Figure 1), led out through the one-trocar hole in the right lower abdomen, and fxed and connected to the external drainage bag. At the end of the operation, the pelvic cavity was rinsed with warm normal saline. If the patient had a chronic disease or weak physique, was elderly, or was unsatisfed with the anastomotic stoma, terminal ileum prophylactic suspension plus abdominal wall skin fxation with an external suspension wire was performed, and a rubber tube was placed in the anal canal to reduce pressure. A ghost ileostomy ( Figure 2) refers to that at the ileum about 40 cm away from the ileocecal valve. A #12 rubber catheter passes through the ileal mesentery, and prophylactic suspension of the terminal ileum is performed. Te suspended terminal ileum remains in the abdominal cavity and is not fxed to the surrounding tissue. Te suspended rubber catheter is led out from the right upper abdominal one-trocar hole and fxed with external abdominal wall skin (with appropriate tightness) to ensure that the intestines are free of torsion and that the blood supply is good. If there is no obvious anastomotic leakage approximately six days after the operation, the rubber catheter can be removed. In the case of anastomotic leakage, the skin of the abdominal wall at which the rubber catheter is fxed is cut into the abdominal cavity according to the layer of the leakage, and the preventively suspended terminal ileum is removed for a colostomy.

Specifc Countermeasures for Preventing Anastomotic
Leakage in Clinic. (A) Prophylactic end ileostomy or transverse colostomy is performed during the operation to divert feces. Tis method is suitable for patients with preoperative neoadjuvant chemoradiotherapy, advancedage patients with chronic diseases, patients with many underlying diseases and a weak physique, patients with anastomosis tension, patients with sphincterpreservingultra-low rectal cancer, and patients undergoing emergency operation due to obstruction. (B) A postoperative end ileostomy or transverse colostomy is performed during the operation to divert feces. Tis method can be applied in the following situations: (1) No prophylactic measures have been taken, and anastomotic leakage occurs after the operation; after active and conservative treatment, the symptoms and signs are not improved, but the patient needs open fushing and drainage, followed by an enterostomy. (2) Prophylactic measures have been taken, and the patient has either undergone a ghost ileostomy or a self-made double cannula has been placed behind the external terminal ileum and presacral anastomosis. After the operation, anastomotic leakage that seems to be not limited occurs. Tus, direct ileostomy and double cannula continuous negative pressure fushing and drainage are performed, and active symptomatic treatment is given. (C) For limited anastomotic leakage, double cannula continuous fushing and negative pressure drainage can be performed immediately, and symptomatic treatment, such as anti-infection therapy, fasting, octreotide inhibition of digestive juice secretion, nutritional support, and rehydration, can be strengthened [9,10]. (D) If the anastomosis is not satisfactory, double cannula continuous fushing and negative pressure drainage should be performed immediately after the operation to keep the pelvic foor clean, which is conducive to the healing of the anastomosis and reduces the occurrence of anastomotic leakage. [11]. (A) Closely observe whether the self-made double cannula drainage is unobstructed or compressed, and whether there is distortion or falling of. If a blockage is found, sterile normal saline can be extracted from the syringe for repeated fushing; in the case of compression and distortion, the position should be adjusted, and the tube must be replaced so that it does not fall of. During the operation, the double cannula must be placed at the lowest position behind the anastomosis to prevent retention of efusion. Efectively control the negative pressure at ≤0.02 MPa to avoid tissue damage or tube blockage in the pelvic cavity due to excessive negative pressure. (B) Te rate of continuous fushing fuid should be continuously adjusted as the drainage volume and nature of the drainage fuid change; the entire operation process must be sterile to prevent exogenous infection. (C) Observe whether the negative pressure introducer is too large or too small and whether the inlet and outlet fuid at either end of the drainage tube are balanced. (D) After continuous fushing and drainage for 4-10 days, if the drainage fuid volume decreases daily and the color of the fushing fuid becomes lighter, the double cannula should be gradually withdrawn until it is completely removed.

Observation Indexes.
Te occurrence and clinical manifestations of anastomotic leakage after laparoscopicassistedsphincter-preserving surgery for middle-and lowgrade rectal cancer in 126 patients were studied and summarized, and the treatment countermeasures and efects were analyzed.

Results
Among the 126 patients with middle-and low-grade rectal cancer undergoing sphincter-preserving surgery under laparoscopy, the distance from the lower edge of the rectal tumor to the anal edge was ≤10 cm. In 81 cases (64.28%), the distance was ≥6.0-10 cm, and in 45 cases (35.72%), the distance was ≥4.5-6.0 cm, 6 developed anastomotic leakage after the operation (leakage rate of 4.7%), comprising 4 male patients and 2 female patients ranging from 35 to 88 years old. On the second and fourth days after the operation, turbid purulent fuid was drained from the abdominal drainage tube in three cases, and on the ffth and sixth days, the abdominal drainage tube drained light yellow liquid in another three cases, with abdominal distension, low fever, and local peritonitis in the lower abdomen. Te anastomotic leakage was diagnosed by CT and digital anal examination. Tese six patients received continuous fushing and negative pressure drainage with a selfmade double cannula and strengthened symptomatic treatment, such as anti-infection therapy. All patients were cured and discharged. Te healing time was 4-10 days, with an average of 5.69 days. Te continuous fushing time was 3-10 days, and the hospital stay length ranged from 8 to 24 days [12]. Regarding the patients with abdominal distension, low fever, and local peritonitis in the lower abdomen, their body temperature returned to normal 3-4 days after continuous fushing with a double cannula. Teir abdominal distension and pain improved signifcantly 5-8 days after the fushing; the fuid drainage decreased, and the color of the fushing fuid became lighter after 9-15 days. At this time, the double cannula was gradually withdrawn until it was completely removed; this operation went smoothly in all patients.

Discussion
In recent years, with the continuous improvement of people's living standards and quality of life and the maturity of endoscopic technology combined with the wide clinical application of staplers, cutting closures, ultrasonic scalpels, and other instruments, patients with middle-and low-grade rectal cancer have demonstrated a signifcantly increased willingness to require preservation of the sphincter during surgery. Tus, clinicians have adopted laparoscopic-assisted radical resection for middle-and low-grade rectal cancer (Dixon), which makes the sphincter-preserving surgery simple and convenient. Anastomosis is a reliable operation that has the advantages of less trauma, a shorter operation time, and rapid postoperative recovery, improving patients' quality of life and the sphincter retention rate. Tis surgical method has also greatly promoted the technological progress of the surgical treatment of rectal cancer. However, there are still complications, such as postoperative anastomotic leakage and bleeding. In this study, the data of 126 patients with middle-and low-grade rectal cancer who underwent the sphincter-preserving surgery under laparoscopy were analyzed and studied. Of these patients, six developed anastomotic leakage after the operation. Tey received continuous fushing with normal saline or continuous washing with normal saline and dripping metronidazole alternately, negative pressure drainage with a self-made double cannula, and strengthened symptomatic treatment, such as anti-infection therapy. All six patients were cured and discharged. Tis suggests that continuous fushing and negative pressure drainage with a self-made double cannula play an obvious role in preventing and treating anastomotic leakage simply, economically, and efectively.
Te clinical study analysis also revealed that the results of timely, efective, and active conservative treatment of anastomotic leakage should be signifcantly better than those of surgical treatment. Most anastomotic fstulas heal 1-3 weeks after conservative treatment [13]. In summary, patients with middle-and low-grade rectal cancer should be fully evaluated before operation to recognize the risk factors for anastomotic leakage. Terefore, adequate perioperative preparation, meticulous operation during surgery, and careful postoperative management are key factors in preventing anastomotic leakage. In the case of such leakage, thorough continuous pelvic fushing and effective pelvic drainage are vital to reducing and controlling abdominal infection and promoting healing of the leakage. It is only in this way that we can ensure the most ideal operation results.

Data Availability
Te data used to support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that there are no conficts of interest.