Duodenal Diverticula

　　Duodenal diverticula usually have no clinical symptoms, so they are not easy to detect in time.This disease was reported for the first time in 1710 by Chimel, and its etiology and mechanism are as follows:.

　　1. Etiology

　　The exact cause of diverticula is not yet clear. Most believe that it is due to congenital maldevelopment or weakness of the limited muscular layer of the intestinal wall. When there is a sudden increase in intraluminal pressure or a long-term or recurrent increase in pressure, the thin spot of the intestinal wall, the mucosal and submucosal tissue of the intestinal mucosa extrude to form diverticula. There are mainly three types as follows:

　　1. Congenital Diverticula

　　This type is rare and is a congenital developmental abnormality that is present at birth. The structure of the diverticular wall includes the intestinal mucosa, submucosa, and muscular layer, which are completely the same as those in the normal intestinal wall and are also called true diverticula.

　　2. Primary Diverticula

　　Due to congenital anatomical defects in some parts of the intestinal wall, increased intraluminal pressure causes the mucosal and submucosal tissue at this location to prolapse outward to form a diverticulum. The muscular layer of the diverticular wall is often absent or thin.

　　3. Secondary Diverticula

　　This type is often caused by scar contraction of duodenal ulcers or adhesion and traction due to chronic cholecystitis, so they all occur in the first part of the duodenum and are also called pseudodiverticula.

　　II. Pathogenesis

　　1. Common Sites

　　Duodenal diverticula are mostly solitary, with multiple occurrences being rare. Primary diverticula are commonly located in the second part of the duodenum in 70% of cases, 20% in the third part, and 10% in the fourth part. Secondary diverticula are more common in the first part of the duodenum. About 85% of diverticula are located on the inner wall of the second part of the duodenum, with the vast majority being near the papilla. Since the diverticula are closely related to the blood vessels and common bile duct that pass through the inner margin of the duodenum, it is believed that duodenal diverticula are caused by the gradual outward protrusion of the intestinal wall through this weakness. The diverticula are often located on the surface or behind the pancreas, or even embedded in the pancreatic tissue. They can often cause obstruction and lead to complications such as cholangitis and pancreatitis.

　　2. Pathological Changes

　　The size and shape of diverticula vary, and they are related to their anatomical location, the effect of intestinal pressure, and the duration of time the diverticulum has been present. They are generally 0.5 to 10 cm in size and can be circular, elliptical, or tubular, among other shapes. The size of the diverticular neck is related to the occurrence of symptoms. If the neck opening is wide, the contents of the diverticulum can be easily drained, and symptoms may not occur for a long time. However, if the opening is narrow, or if it becomes narrow due to inflammation and the diverticulum enlarges, intestinal contents or food may remain in the diverticulum, leading to decay of food residue, bacterial infection, diverticulitis, intestinal stones, and other complications.

　　3. Pathological Classification

　　According to the direction of the diverticular protrusion and its relationship with the duodenal lumen, they can be divided into intraluminal and extraluminal diverticula. The common clinical type is the extraluminal diverticulum, while the intraluminal diverticulum is rare.

　　(1) Intraluminal diverticula: The diverticular wall is composed of two layers of intestinal mucosa and a small amount of submucosal connective tissue in between, appearing as polypoid or sac-like and attached near the duodenal papilla. It feels like an intestinal polyp when touched outside the intestinal lumen. In some cases, the duodenal papilla is located inside the diverticulum. Therefore, it is prone to cause biliary and pancreatic diseases, as well as obstruction of the duodenal lumen, and complications such as gastric and duodenal ulcers. Such cases often accompany congenital malformations of other organs.

　　(2) Extraluminal diverticula: Diverticula are mostly circular or lobulated, with necks that can be wide or narrow. They are usually solitary, but about 10% of patients may have two or more extraluminal diverticula or coexisting diverticula in other parts of the digestive tract. Approximately 70% are located on the inner side of the descending duodenum, closely related anatomically to the pancreas, while 30% are in the transverse or ascending parts.

　　The size and shape of diverticula vary, but most of them have a smaller orifice. Once the intestinal contents enter the diverticulum and are not easily discharged and retained, various complications can occur; or even if there is no retention of intestinal contents in the diverticulum, it may compress adjacent organs and cause complications. Therefore, it is important to understand some pathological changes caused by diverticula. Specifically, see as follows:

　　1. Diverticulitis and diverticular hemorrhage Due to the retention of duodenal diverticular contents, bacterial proliferation, inflammatory infection can cause diverticulitis followed by mucosal erosion and bleeding. There are also ectopic gastric mucosa and ectopic pancreatic tissue in the diverticulum, causing bleeding, or diverticular inflammation erodes or perforates nearby blood vessels causing massive hemorrhage, as well as rare mucosal malignant transformation in the diverticulum causing hemorrhage.

　　2. Diverticular perforation Due to the retention of diverticular contents, mucosal inflammatory erosion and ulcer perforation often occur retroperitoneally, with atypical symptoms after perforation, even laparotomy may not find it, usually presenting with retroperitoneal abscess, pancreatic necrosis, and pancreatic fistula. If peritoneal cellulitis around the duodenum or leakage of bile and pancreatic juice is found during laparotomy, the possibility of diverticular perforation should be considered, and the lateral peritoneum should be incised for careful exploration.

　　3. Duodenal obstruction Duodenal obstruction caused by diverticula is more common in intraluminal diverticula, due to the diverticulum filling to form a polypoid sac bag and block the intestinal lumen. Or larger extraluminal diverticula may cause obstruction due to content retention and compression of the duodenum, but most are incomplete obstructions.

　　4. Obstruction of bile and pancreatic ducts Commonly seen in paraampullary diverticula, both intraluminal and extraluminal types can occur. Because the opening of the common bile duct and pancreatic duct is at the lower or lateral side of the diverticulum, even at the edge or inside the diverticulum, it leads to dysfunction of the Oddi sphincter; mechanical compression of the common bile duct and pancreatic duct by the diverticulum causes bile and pancreatic juice stasis, increasing intraluminal pressure, duodenal papilla edema, distal common bile duct edema, increasing the opportunity for retrograde infection and concurrent bile duct infection or acute or chronic pancreatitis.

　　5. Surgical complications Due to the lack of muscularis mucosae tissue, thin walls, and adhesion to surrounding tissues, the diverticulum is easily torn and the surrounding organs are damaged during dissection, or due to poor suture, common surgical complications include:

　　Duodenal fistula: a serious complication with a high mortality rate, often occurring during the resection of paraampullary diverticula. The key to preventing the occurrence of fistula is to perform gentle and meticulous dissection when separating the diverticulum, and to suture tightly. Once it occurs, it must be drained in time to prevent the development of severe peritonitis; gastroenteric decompression, anti-infection, nutritional support, and maintaining good water and electrolyte balance are generally required for treatment, and the fistula can gradually heal.

　　Obstructive jaundice and pancreatitis: often due to accidental injury to the bile duct or pancreatic duct during the resection of diverticula, or due to local narrowing of the distal common bile duct or ampulla caused by inversion and closure of the diverticulum. Clinical manifestations include upper abdominal pain, fever, and jaundice, and require reoperation to relieve obstruction. To avoid this complication, the bile and pancreatic ducts should be carefully identified during surgery, and excessive resection of the duodenal mucosa should be avoided to affect the patency of the bile duct opening. Generally, a preoperative incision of the common bile duct should be made before resecting the diverticulum, inserting a catheter into the ampulla to mark the position of the bile duct opening, and then separating the diverticulum, preventing the accidental suture of the bile duct opening part to cause bile duct stenosis.

　　There are no typical clinical symptoms of duodenal diverticula, which are only occasionally found in X-ray barium contrast examination, fiberoptic endoscopy, laparotomy, or post-mortem examination. The size of the diverticula is not positively correlated with the degree of symptoms. When the diverticula are complicated by inflammation, symptoms such as discomfort in the upper abdomen, pain in the upper right abdomen or around the umbilicus, nausea, vomiting, hiccups, bloating, diarrhea, and even hematemesis and hematochezia may occur. Diarrhea may be caused by malabsorption due to impaired pancreatic function or excessive bacterial overgrowth in the diverticula. If the diverticula perforate, it can cause symptoms of peritonitis, and the perforation embedded in the pancreas can cause severe pain and symptoms of acute pancreatitis: increased blood and urine amylase; if the diverticula compress the common bile duct, symptoms such as bile duct obstruction, fever, jaundice, upper abdominal distension may occur. If there is a localized deep tenderness in the upper abdomen, right of the midline fixed in the diverticula area, it may indicate the presence of chronic diverticulitis.

　　There are no typical clinical symptoms of duodenal diverticula, which are only occasionally found in X-ray barium contrast examination, fiberoptic endoscopy, laparotomy, or post-mortem examination. It is particularly important to pay attention to the prevention of upper gastrointestinal inflammation in daily life.

　　1. Eat in small portions and frequently, at regular intervals. Five to seven meals a day, eating in small portions and frequently can neutralize stomach acid, reduce the stimulation of stomach acid on the ulcer surface, and provide nutrition, which is conducive to the healing of the ulcer surface, and is more suitable for acute peptic ulcers.

　　2. Avoid foods with excessive mechanical and chemical stimulation. Mechanical stimulation increases damage to the mucosa, destroys the mucosal barrier, such as coarse grains, celery, chives, snow vegetables, bamboo shoots, and dried fruits; chemical stimulation will increase gastric acid secretion, which is not conducive to the healing of ulcers, such as coffee, strong tea, strong alcohol, strong meat soup, etc. It is禁忌 acid-producing foods such as sweet potatoes, potatoes, overly sweet pastries, and sugar and vinegar foods; gas-producing foods such as raw scallions, garlic, radishes, garlic oil, onions, etc.; cold foods such as large amounts of cold drinks, cold mixed vegetables, etc.; hard foods such as preserved pork, ham, sausages, clam meat, etc.; strong seasonings such as pepper, curry powder, mustard, chili oil, etc.

　　3. Choose a balanced diet with high nutritional value, soft and easy to digest, such as milk, eggs, soy milk, fish, lean meat, etc., after processing and cooking to make it soft and easy to digest, without irritation to the gastrointestinal tract; at the same time, supplement sufficient calories, protein, and vitamins; the nutrient ratio during the semi-liquid period is 55% carbohydrates, 15% protein, and 30% fat; during the liquid period, it is 60% carbohydrates, 20% protein, and 20% fat.

　　In addition, maintain a regular lifestyle and a comfortable mood. By strengthening exercise, improve the body's immune function and intestinal transportation and transformation function.

　　The diagnosis of duodenal diverticula relies on examination and laboratory tests, as they often have no clinical symptoms. This disease mainly includes imaging examinations, specifically as follows:

　　1. X-ray barium meal examination

　　Duodenal diverticula can be detected, manifested as sac-like shadowing that protrudes from the intestinal wall, with a regular and clear contour, smooth edges. After compression, mucosal ridges can be seen extending into the duodenum from the shadow. Some shadows can be seen after the barium is excreted, which are shadows of barium remaining in the diverticulum cavity. Larger diverticula with wider necks may sometimes show a liquid-gas interface within the diverticulum. When the intestinal mucosal folds around the diverticulum become thickened and irregular, there are signs of irritation or the emptying of the diverticulum is prolonged, or there is localized tenderness, it can be considered as the manifestation of diverticulitis. If the diverticulum is fixed and cannot be moved, it is indicative of peridiverticulitis.

　　Secondary duodenal diverticula are often accompanied by irregular deformation of the duodenal bulb and shadows of intestinal dilation. When the diverticula are small or the neck is narrow, the opening is often concealed by the intestinal mucosal folds, or the diverticulum is filled with a large amount of food residue, making it difficult to detect the presence of diverticula. If a small amount of barium enters the diverticulum or a complete or incomplete ring shadow can be seen, low-pressure duodenal barium X-ray contrast examination can increase the detection rate of diverticula.

　　2. Fiberoptic duodenoscopy

　　In addition to detecting the orifice of the diverticulum, it can also understand the relationship between the diverticulum and the ampulla of Vater, providing a basis for determining the surgical plan.

　　3. Cholangiography

　　Methods such as intravenous cholangiography, percutaneous transhepatic cholangiography (PTC), and retrograde cholangiography through duodenoscopy (ERCP) can be used to examine the relationship between the diverticulum and bile ducts, pancreatic ducts, and provide reference for the selection of surgical treatment methods.

　　4. CT examination

　　Diverticula usually manifest as circular or ovoid sac-like shadows protruding from the duodenal mucosal wall, with a smooth serosal contour. Due to the fact that diverticula are often connected to the intestinal lumen by a narrow neck, CT not only can show the contrast enhancement entering the diverticulum but also commonly shows gas shadows within it. It should be noted that when positive contrast material enters the diverticulum on the inner side of the descending duodenum, it may be mistaken for a lower end bile duct stone.

　　The diverticula of the descending duodenum are usually located near the ampulla of Vater, and CT shows a sac-like contrast enhancement that protrudes outward between the descending duodenum and the head of the pancreas, extending beyond the contour of the descending duodenum; when positive contrast material fails to enter the diverticulum, it appears as a low-density liquid shadow. The diverticula in the horizontal and ascending segments appear as sac-like shadows above or below the main intestinal plane, and the diverticula located on the superior wall often contain gas. When the diverticula are large, they may resemble the shape of the intestinal tract. At this time, attention should be paid to the observation of continuous sections to clarify their relationship with the intestinal tract. When associated with diverticulitis or peridiverticulitis, the diverticulum wall thickens, and edema appears on the intestinal wall or surrounding area, with reduced density and associated with linear shadows, increased fat-space density. Diverticulitis occurring on the inner wall of the descending duodenum is mainly manifested by an increased distance between the duodenum and the head of the pancreas, with the appearance of low-density shadows between them, while the outer wall of the descending duodenum remains normal; the edema and thickening caused by duodenal ulcers are characterized by a circumferential change centered on the intestinal tract.

　　Pay attention to regular diet for duodenal diverticula, and the diet should be rich in nutrition and easy to digest. Specific attention should be paid to the following 5 points:
　　1. Small and frequent meals, regular timing and quantity, avoiding foods with strong mechanical and chemical stimulation, such as coarse grains, celery, chives, snow peas, bamboo shoots, dried fruits, coffee, strong tea, and strong alcohol.

　　2. Ensure a balanced diet, such as milk, eggs, soy milk, fish, lean meat, etc. Sufficient protein should be provided to meet the body's needs, and there is no need to strictly limit fat, as it can inhibit gastric acid secretion. Appropriate fat does not irritate the gastrointestinal mucosa, but excessive fat can promote the secretion of cholecystokinin, inhibit gastrointestinal motility, and it is advisable to choose easily digestible and absorbable creamy fat, such as milk, butter, egg yolks, cheese, and an appropriate amount of vegetable oil.

　　3. Carbohydrates have no stimulatory effect on gastric acid secretion and do not inhibit gastric acid secretion. 300-350g can be provided daily, thick congee, noodles, wontons, etc., are all easily digestible staple foods.

　　4. Supplementing foods rich in B vitamins, vitamin A, and vitamin C.

　　5. Cooking methods. Patients should try to choose steaming, boiling, blanching, soft braising, stewing, etc., and should not use methods such as frying, roasting, stir-frying, pickling, and cold mixing for food processing.

　　Duodenal diverticula without symptoms do not require treatment. For duodenal diverticula with symptoms, non-surgical treatment should be considered first after excluding the presence of other lesions. Specific measures are as follows:
　　I. Non-surgical treatment
　　Adjust the diet, take adequate rest, administer antacids and antispasmodic drugs, use positional drainage to assist in the emptying of the contents of the diverticulum, reduce stasis, apply antibiotics and gastric tube decompression, etc., to alleviate or fade general symptoms. When non-surgical treatment is ineffective, or there are serious complications such as bleeding and obstruction, and no other lesions are found, surgical treatment may be considered.
　　II. Surgical treatment
　　Surgical resection of the diverticulum is an ideal treatment, but the wall of the duodenal diverticulum is thin and adherent, and it is easy to tear during resection. When the diverticulum is located at the head of the pancreas, there is a lot of bleeding during separation, and it is easy to injure the pancreas and bile ducts, etc. Therefore, the surgical method must be carefully selected and should not be rushed.
　　1. Indications for surgery: Duodenal diverticula may be considered for surgery under the following conditions:
　　(1) The neck of the diverticulum is narrow, the contents of the diverticulum are retained, there are obvious symptoms of diverticulitis, and repeated内科(treatment) has been ineffective;
　　(2) Diverticula with bleeding, perforation, or abscess formation;
　　(3) Diverticula are large and distended, compressing the common bile duct or pancreatic duct, causing obstruction and abnormal opening of the bile and pancreatic ducts into the diverticula, leading to lesions in the biliary and pancreatic systems;
　　(4) Diverticula with polyps, tumors, parasites, and other properties that cannot be clearly identified.
　　2. Preoperative preparation: In addition to the general preoperative preparation for gastrointestinal surgery, it is necessary to understand the location of the diverticula and their relationship with surrounding organs. Accurate positioning is conducive to exploration during surgery and the selection of surgical methods. The upper gastrointestinal X-ray contrast should be taken in the left anterior oblique and right anterior oblique positions to determine the location of the diverticula in the anterolateral or posterolateral side of the duodenum, their relationship with the parenchyma of the pancreas and the course of the bile duct, and the relationship between the opening of the diverticula and the papilla of the duodenum. It is best to perform endoscopy and biliary contrast examination before surgery for diverticula located on the medial side of the descending part to understand the relationship between the diverticula and the papilla of the duodenum and the bile duct. It is necessary to insert a gastric tube, and air can be injected through the gastric tube during surgery if necessary to inflate the diverticula, making it easier to display the location of the diverticula.
　　3. Common surgical methods: There are different approaches to expose the diverticula during surgery, depending on the location of the diverticula; for diverticula located in the third and fourth parts of the duodenum, the transverse mesocolon should be incised to expose the diverticula; for diverticula on the anterolateral side of the descending part of the duodenum, the anterolateral margin of the descending part should be dissected; for diverticula on the posterolateral side of the descending part, the lateral peritoneum of the duodenum should be incised, and the duodenum should be flipped to the left anterior side to expose the diverticula.
　　Surgical methods, in principle, the resection of diverticula is the most ideal. For smaller diverticula, only inversion surgery can be performed. When multiple diverticula are present and it is difficult to perform resection techniques, translocation surgery can be adopted, that is, partial gastrectomy in the Billroth II manner and selective vagotomy. If it is difficult to find the diverticula during surgery, the duodenum can be incised from the inside to find the opening of the diverticula, flip the bottom into the intestinal lumen for resection and treatment. After resection of the diverticula, the incision of the intestinal wall should be inverted and sutured vertically to the long axis of the intestinal curvature to prevent intestinal stricture.
　　4. Postoperative management: Duodenal surgery is a high-risk operation, and postoperative management is very important. The main measures include:
　　(1) Major surgery of the duodenum, especially for patients with poor conditions and complications, should be monitored for vital signs after surgery;
　　(2) Continuous duodenal decompression (send the distal end of the gastric tube to the descending part of the duodenum) for 3 to 5 days;
　　(3) For patients who undergo duodenal stenting, the stent must be properly fixed, and it can be removed after 15 days according to the situation;
　　(4) Other diseases should be treated strictly according to the routine postoperative treatment of gastrointestinal surgery.