I. Laparoscopic gastric surgery 1. Laparoscopic surgery for ulcer disease: Although not routinely used, the status of laparoscopic techniques for ulcer perforation repair has been established. Many open surgeries such as: gastroduodenal ulcer perforation repair, vagotomy and major gastrectomy can be done laparoscopically. Laparoscopic ulcer perforation repair is similar to the open surgical approach, with the outstanding advantages of clear diagnosis, easy operation, good results, and rapid control of peritonitis after perforation repair and adequate flushing of the peritoneal cavity [1]. The perforation can be sutured directly under the microscope, or can be plugged with fibrin glue or filled with large omental tissue cover [2]. Laparoscopic completion of major gastric resection and reconstruction first appeared in 1992 and is mainly used for the treatment of scarring pyloric obstruction caused by ulcers and huge, refractory and suspected malignant gastric ulcers, and also for the resection of larger benign tumors of the stomach. 2, laparoscopic surgery for obesity: at the end of the 1980s, laparoscopy began to be introduced into obesity surgery and achieved rapid development, and now the commonly used bariatric surgery can be performed under laparoscopy [3]. the study of Lee et al [4] showed that compared with open surgery, laparoscopic bariatric surgery has outstanding minimally invasive effect, at the same time, the gastroesophageal area is well exposed, the postoperative cosmetic effect is good, and incisional hernia and intestinal adhesions can be avoided, etc. Complications occur. However, it requires certain equipment and high operating techniques, and the operation time is slightly longer than that of open surgery, and the cost is higher. Laparoscopic gastric Roux-en-Y bypass (LRGB), laparoscopic vertical banded gastroplasty (LVBG), and laparoscopic adjustable banded gastric reduction ( 1aparoscopic adjustable gastric banding (LAGB) are the three most common procedures used to treat morbid obesity. Among these three procedures, LRGB has been shown to have the best long-term weight reduction effect in the treatment of patients with severe obesity, with the disadvantage that the procedure is more complicated, with high perioperative complications and a certain surgical mortality. The long-term follow-up of patients with LVBG proves that because patients tend to change their dietary habits to high sweet and high calorie liquid food, the long-term weight gain after surgery is significantly increased. the minimally invasive nature of LAGB is an extremely prominent advantage, because it does not change the normal anatomy of the gastrointestinal tract, the surgical operation is relatively simple, and the perioperative complication rate is much lower than that of other surgical procedures, so it has become a hot spot for research in recent years [5]. 3. laparoscopic surgery for reflux disease: for GERD (gastroesophageal reflux disease), although proton pump inhibitors are very effective in reducing reflux symptoms, the recurrence rate is as high as 80% after discontinuation of the drug. the Nissen fundoplication is a very effective surgical procedure for GERD. in 1956 Nissen first reported this surgical approach and Dallemagne first described the laparoscopic Nissen fundoplication in 1991. Laparoscopic Nissen fundoplication has become the standard surgical procedure for the treatment of GERD, which in the short term can greatly improve the symptoms of esophageal reflux thus improving the quality of life of patients and increasing their cure rate to more than 90% [6,7]. The most common and important postoperative complication is dysphagia, with a reported incidence of up to 100% in the early stage and 2% to 31% in the long term, which is very difficult to manage and requires adequate experience of the operator. 4, laparoscopic surgery for intraluminal gastric diseases: Bhoyrul et al. were the first to perform studies that applied the environment and advantages of laparoscopic surgery to the cavernous organs. Endoluminal surgery represents another possible area of entry for minimally invasive surgery. This technique requires the use of a special puncture trocar, the Radially Expanding Device (RED), which allows laparoscopic access to almost all parts of the gastrointestinal tract. The most performed procedures are gastric anastomosis for pancreatic pseudocysts and resection of gastric smooth muscle tumors, resection of gastric mucosal tumors, and treatment of bleeding ulcer disease [8,9]. After passing through the anterior abdominal wall into the abdominal cavity, the rigid puncture trocar used for endoluminal surgery must also pass through the anterior wall of the stomach into the gastric cavity, a situation that limits endoluminal surgery to the treatment of lesions on or near the posterior wall of the stomach. 5.Laparoscopic surgery for gastric cancer: Surgery for gastric cancer requires high surgical techniques due to rich blood supply, multiple anatomical levels and complex anastomosis, so laparoscopic surgery for gastric malignant tumors is slow in development. For early gastric cancer that only invades the mucosal layer and has no lymph node metastasis, laparoscopic local gastric resection, such as 1aparoscopic wedge resection (LWR) and intragastric mucosal resection (IGMR), can be used. Laparoscopic radical resection of gastric cancer can be divided into three types: completely laparoscopic, laparoscopically assisted, and hand-assisted laparoscopic radical resection of gastric cancer. Depending on the location of the tumor, laparoscopic radical gastrectomy can be divided into laparoscopic major distal gastrectomy (LADG), laparoscopic major proximal gastrectomy (LAPG), and laparoscopic total gastrectomy (LATG). Currently LADG is the most commonly used surgical procedure. For radical resection of tumors, the most discussed issues are the number of gastric margins and lymph node dissection. Many clinical studies have shown that laparoscopic D2 lymph node dissection for progressive gastric cancer is feasible and safe, and can achieve the same radical results as open surgery. Regarding the evaluation of the advantages of laparoscopic radical gastric cancer surgery, many scholars have compared the operative time, bleeding volume, complication rate, mortality rate, postoperative gastrointestinal function recovery time, and postoperative hospital stay between laparoscopic surgery and similar open surgery. It is believed that laparoscopic radical gastric cancer surgery has less bleeding, less postoperative pain, faster recovery of postoperative gastrointestinal function, and shorter postoperative hospital stay, which fully reflects the minimally invasive advantages of laparoscopy [10]. Second, laparoscopic small bowel surgery 1, laparoscopic small bowel adhesion release: intestinal obstruction after surgery is a common postoperative complication, and 49%-74% of small bowel obstruction is caused by intra-abdominal adhesions [11]. Laparoscopic surgery can completely release abdominal adhesions and has the advantages of less trauma, less gastrointestinal interference, abdominal wall incision far from the original abdominal adhesions, early bedtime activity, and early recovery of gastrointestinal function, and the chance of re-forming adhesions after surgery is significantly reduced compared with open surgery [12]. The most common complication is an undetected intestinal fistula at the time of intestinal adhesion release. There is a risk of splitting the plasma membrane during the release of intestinal adhesions, which needs to be repaired. In many cases of laparoscopic small bowel adhesion release, the author found that pathological intestinal collaterals caused by severe adhesions, which are estimated to form adhesions again after surgery or have obvious obstacles to the passage of intestinal contents, should be decisively removed, otherwise they may be obstructed again after surgery and have to be operated twice. 2, laparoscopic small bowel resection: laparoscopic small bowel resection can be used for a variety of small bowel diseases, and lesions such as small bowel stenosis or mesenteric vascular injury can be found microscopically, and benign and malignant small bowel tumors can be easily detected. The most difficult to identify smooth muscle tumors or polyp-like lesions in the intestinal cavity, endoscopic activated charcoal injection before laparoscopic surgery is beneficial for intraoperative identification. When small bowel resection is required for upper gastrointestinal bleeding, dye can be injected according to the site identified by angiography, and the extent of bowel resection can be determined according to the area of small bowel plasma membrane staining. For those with multiple negative preoperative examinations and high clinical suspicion of small bowel lesions, laparoscopic exploration can both clarify the diagnosis and administer radical treatment. There are two types of surgery: total laparoscopy and laparoscopy-assisted small bowel resection. Laparoscopic-assisted small bowel resection is more practical and easy to perform, and after lesion removal, intestinal anastomosis is performed outside the body. Because the specimen is often removed after total laparoscopic small bowel resection by enlarging the incision to 3 cm, which is sufficient for laparoscopic-assisted small bowel resection. III. Laparoscopic appendectomy The world’s first laparoscopic appendectomy was reported by Dr. Semn in Germany in 1983, 4 years before the first laparoscopic cholecystectomy. The indications for laparoscopic appendectomy are the same as those for open appendectomy, and appendiceal perforation or abscess is not a contraindication to surgery, and laparoscopic exploration has significantly improved the accuracy of surgical diagnosis. The operative time is slightly longer compared to open surgery. Specimens for laparoscopic appendectomy are removed through specimen bags, resulting in a significant decrease in incisional infection rates. However, there is a relative increase in the cost of instrumentation. ball et al [13] showed that for complex appendectomy, laparoscopic surgery is safer and more effective than open surgery. IV. Laparoscopic colorectal surgery The anatomical features of the colorectum make it suitable for laparoscopic surgery. The first case of laparoscopic colorectal surgery was completed in 1990. With the improvement of surgical techniques and instruments and equipment, the indications for surgery and the scope of surgery are still expanding. 1, laparoscopic surgery for benign colorectal diseases: laparoscopic surgery has become the ideal method for experienced surgeons to treat benign colorectal diseases [14]. Commonly used procedures include: (1) laparoscopic colonic diverticulectomy: the diverticulum is cut from the root with ENDO-GIA and repaired if necessary. (2) Laparoscopic partial colectomy: for resection of benign colonic tumors, such as adenomas and smooth muscle tumors that cannot be removed by colonoscopy. (3) Laparoscopic total colectomy: for lesions involving the whole colon, such as multiple polyps, segmental colitis, etc., which are difficult to operate and are less frequently used at present. (4) Laparoscopic rectal fixation: used for the treatment of rectal prolapse, laparoscopy can provide a clear view for separating the anterior sacral space and the anterior rectum and reduce side injuries. The polypropylene mesh can be fixed to the sacrum with titanium nails, or the mesh can be sutured to the sacrum with a microscopic suture technique. 2.Laparoscopic surgery for colorectal cancer: laparoscopic colorectal cancer surgery is now widely carried out all over the world, and there have been a lot of clinical studies showing the clinical efficacy and minimally invasive superiority of laparoscopic radical surgery for colon cancer and laparoscopic radical surgery for rectal cancer. The surgical complications are not significantly different from those of open surgery, and the operation time and intraoperative bleeding are better than those of the open group. Total rectal mesenteric resection for middle and low rectal cancer is more advantageous when operated under laparoscopy: more accurate judgment of the lax tissue gap between the two layers of the pelvic fascia visceral wall, more accurate protection of the pelvic plexus by the magnifying effect of laparoscopy on the local field of view, more complete resection of the rectal mesentery by ultrasonic knife along the sharp dissection of the pelvic fascia gap, and strict control of oncological surgical standards by monitoring and recording the surgical operation process through the screen. Numerous clinical studies have reported that the length of bowel resection in laparoscopic colorectal cancer resection is adequate. There is no difference in the number of lymph nodes cleared compared with similar open surgery. Metastasis from the perforation hole of the cancer is not specific to laparoscopy, but is associated with improper operative technique. Recent clinical reports on prospective randomized controlled studies of laparoscopic colorectal cancer surgery have shown no difference in 3- and 5-year survival rates between laparoscopic colorectal cancer surgery and comparable open surgery [15].