In recent years, endoscopic minimally invasive treatment techniques have made rapid progress. In the treatment of malignant gastrointestinal obstruction, self-expanding metal stents placed via large caliber (≥3.7 mm) endoscopic clamp tracts have been gradually applied in the treatment of malignant gastric outlet or duodenal obstruction and malignant colorectal obstruction, which have partially replaced surgical bypass surgery (i.e., emergency abdominoplasty) while achieving good clinical outcomes. In this article, we will briefly describe the application of intestinal endoprosthesis in gastric outlet-duodenal obstruction and colonic obstruction.
Gastric outlet-duodenal obstruction is a common comorbidity of unresectable distal gastric cancer, duodenal cancer and pancreatic cancer, of which about 15-20% of pancreatic cancer patients can develop gastric outlet-duodenal obstruction. Other causes of obstruction include peri-pot belly cancer, lymphoma and metastatic cancer of duodenum or proximal jejunum. Gastric outlet-duodenal obstruction can cause nausea, intractable vomiting, esophagitis, electrolyte imbalance, malnutrition, and severe dehydration. The traditional palliative treatment is open or laparoscopic gastro-jejunal anastomosis. However, even with laparoscopic surgery, there is a high rate of complications and mortality. Therefore, endo-intestinal stenting is increasingly gaining attention as a minimally invasive alternative treatment.
Indications and contraindications It is mainly used for stenosis due to malignant tumors of the gastric sinus and duodenum and obstruction due to direct invasion or extraluminal compression of pancreatic and biliary tumors. The only absolute contraindication is perforation of the gastrointestinal tract.
The operation should be performed in a room with X-ray fluoroscopy. Preoperative imaging to understand the anatomy of the lesion and the length and extent of the stricture will help the operation. Biliary obstruction often occurs in combination with gastric outlet-duodenal obstruction (especially in patients with pancreatic cancer) and often precedes gastric outlet obstruction. In patients with coexisting or impending biliary obstruction, the biliary stent should be placed before the duodenal stent is placed, because once the duodenal stent is placed, it is difficult for the biliary stent to enter the bile duct through the papilla. Biliary obstruction that occurs after duodenal stent placement is often treated by a percutaneous, transhepatic route.
The most commonly used intestinal stent for gastroduodenal use is the Wallstent, an uncoated metal stent available in 20 mm and 22 mm bore with a 10 Fr diameter release system ranging from 160 cm to 255 cm in length. More recently, BostonScientific has also introduced the intestinal stent WallFlex, a nickel-titanium alloy stent with a 22mm body diameter and a 27mm proximal umbilical diameter, available in 6cm, 9cm and 12cm lengths. Both stents can be released through the clamp channel of a therapeutic endoscope. There are two ways of stent placement: transendoscopic clamp tract release (TTS) and release via guidewire (OTW). Compared with the OTW method, the TTS operation is more advantageous, as follows: it can be released under the double surveillance of endoscopy and X-ray at the same time, with accurate positioning; the proximal stenosis can be identified more clearly under the endoscope, and it is easy to complete the operation of the guidewire through the stenosis; the insertion of the stent pusher through the endoscopic clamp channel can effectively avoid the pusher from knotting in the wide gastric lumen during insertion; the operation is convenient and fast.
II. Treatment of colonic obstruction Colonic obstruction is a life-threatening disease, and about 8-9% of patients with colon cancer will develop obstruction. In addition, some other pelvic malignant tumors (such as prostate cancer, bladder cancer, ovarian cancer) sometimes also invade or externally press the intestinal wall to cause colon obstruction. Colonic obstruction due to colon cancer often requires emergency surgery. At the same time, due to the inability to perform adequate bowel preparation before surgery, stage I anastomosis is often not possible and colostomy is required, which significantly increases the mortality rate, hospital stay and cost compared with patients undergoing elective surgery. With the use of intestinal stents in the clinic, we have a new alternative to emergency surgery that allows patients to not only decompress and cleanse the bowel preoperatively, but also makes a phase I anastomosis possible.
Indications Indications for colonic stenting include: 1. for colon cancer that can be resected radically, as a preoperative alternative to colostomy in the presence of intestinal obstruction; 2. for advanced colon cancer that cannot be resected, as a means of palliative treatment; 3. for colon obstruction due to metastatic cancer or external pressure lesions; 4. overlying stents for colonic vesicovaginal fistula, internal colonic fistula or colonic vaginal fistula; 5. The use of stents in colonic obstruction due to benign lesions is still controversial.
Operative technique The basic procedure is the same as that for gastric outlet-duodenal obstruction. The application of the TTS approach for colonic stenting, in addition to the same advantages mentioned above, helps to complete the treatment of malignant obstruction of the proximal colon (above the transverse colon), which is difficult to accomplish with the OTW approach (the OTW approach is often limited to the left hemicolectomy).