Para duodenal hernia

　　1. Etiology

　　There are several crypts behind the normal retroperitoneum, such as the superior and inferior duodenal crypts, paraduodenal crypts (Landzerts crypt), posterior duodenal crypt, duodenojejunal crypt, and abdominal wall crypt of the small intestinal mesentery (Waldeyers crypt), etc. They are generally small and do not cause pathological phenomena. If the midgut twists abnormally during embryonic development, part of the small intestine or loops is enclosed in a retroperitoneal pouch, forming a paraduodenal hernia.

　　2. Pathogenesis

　　The pathogenesis of paraduodenal hernia is not yet clear.

　　Treitz (1857) first described many folds and crypts in the paraduodenal area. Jonnesco (1889-1890) divided them into two types: left-sided paraduodenal hernia and right-sided paraduodenal hernia, and found that the left-sided paraduodenal hernia was more common. B.G.A. Moynihan (1899) described nine different crypts around the duodenum and proposed in 1906 that the paraduodenal crypts become larger and deeper to form paraduodenal hernias. The Landzerts crypt is the main cause of left-sided paraduodenal hernias, and the Waldeyers crypt is the cause of right-sided paraduodenal hernias. Andrews (1923) proposed the 'midgut developmental disorder theory', believing that paraduodenal hernia is 'a congenital mesenteric developmental abnormality where the small intestine is enclosed in a retroperitoneal pouch above the colon'. Most scholars currently agree with the latter theory.

　　The normal development of the embryo reaches the 5th week, due to the faster growth rate of the midgut compared to the coelom, it temporarily protrudes into the umbilical cord to form a physiological umbilical hernia. The midgut is divided into two parts, the anterior segment and the posterior segment, by the superior mesenteric artery. The anterior segment of the midgut develops into most of the small intestine, and the posterior segment develops into the distal ileum and the right half of the colon. About 10 weeks later, as the volume of the coelom increases, the midgut located outside the coelom and protruding into the umbilical cord begins to shrink back into the coelom. The anterior segment of the midgut first retracts into the abdominal cavity, passes below the superior mesenteric artery, and rotates counterclockwise. The anterior segment rotates to the left side of the superior mesenteric artery, and the posterior segment rotates counterclockwise above the mesenteric artery to the right. As a result, the cecum and ascending colon are transferred to the lower right abdomen, and the small intestine is located below the transverse colon. Some scholars divide this process into three stages: Stage I, starting from the 5th week of embryonic development, due to the faster growth rate of the midgut compared to the coelom, it temporarily protrudes into the umbilical cord through the umbilical ring to form a physiological umbilical hernia; Stage II, the anterior segment (duodenal part) retracts into the abdominal cavity, behind the superior mesenteric artery, and rotates counterclockwise for 270 degrees; Stage III, the posterior segment (right half of the colon) retracts into the abdominal cavity, in front of the mesenteric artery, rotates counterclockwise for 270 degrees, until this rotation ends at 12 weeks, the right half of the colon moves to the normal position on the right lower abdomen, but the fixation of the intestinal tract and its mesentery may not be completed until birth.

　　The right para-duodenal hernia is caused by the inability of the anterior segment of the mesenteric artery of the middle intestine to rotate counterclockwise or incompletely rotate. It often occurs in the second stage of the rotation of the middle intestine, where the rotation stops after only 90° and remains in the upper right abdomen. During this process, the posterior segment of the mesenteric artery of the middle intestine rotates normally and covers it, causing a large amount of adjacent small intestine to be covered by the right colon mesentery, located within the Waldeyer's recess and fixed with the right posterior peritoneum. This leads to part or all of the small intestine being enveloped behind the cecum and ascending colon mesentery, eventually forming the right para-duodenal hernia. The superior mesenteric artery and ileocolic artery form the anterior margin of the hernia ring, and the ascending colon and its mesentery form the anterior wall of the hernia sac. Therefore, when surgically treating the right para-duodenal hernia, it is often necessary to closely separate the right colon, move the colon to the left side of the abdomen, and leave the small intestine on the right side. Callander (1935) proposed that the mechanism of occurrence of the left para-duodenal hernia is different from that of the right. Normally, the anterior segment of the mesenteric artery of the middle intestine is located on the left side of the superior mesenteric artery, the right half of the colon is located in the normal position in the lower right abdomen, and the duodenum and its mesentery fuse with the posterior peritoneum of the retroperitoneum. If this fusion does not occur, a potential space (Landzerts recess) can be produced. When the small intestine moves to the left posterior upper abdomen, it falls into the Landzerts recess, and the small intestine is enveloped below the descending colon mesentery, forming the left para-duodenal hernia. The descending colon and its mesentery form the anterior wall of the hernia sac, the inferior mesenteric vessels form the anterior margin of the hernia ring, leading to the cecum located on the right side of the median line in the lower abdomen.

　　The orifice of the left para-duodenal hernia opens to the right, and the peritoneum in its anterior margin has the inferior mesenteric arteries and veins passing through. The hernia sac is located in the Landzerts recess on the left side of the mesentery of the small intestine, with the descending colon mesentery in front and the psoas major muscle, left kidney, and ureter at the back. The descending colon can be pushed to the left side of the hernia sac or straddle the front of the hernia. The orifice of the right para-duodenal hernia opens to the left, and the anterior margin of the hernia ring has the superior mesenteric arteries and veins or ileocolic artery passing through. The hernia sac is located in the Waldayer's recess on the right side of the mesentery of the small intestine, behind the transverse colon mesentery. The hernia sac of para-duodenal hernia is a single-layer peritoneum. The contents of the hernia are mostly small intestine, which can be a single intestinal loop or the entire small intestine.

　　When there are no obvious pathological changes such as compression, adhesion, or torsion of the hernia ring or intestinal tract in the hernia sac, some patients with para-duodenal hernia may have no obvious symptoms. When the hernia ring compresses, adheres to the neck of the hernia sac, or twists within the hernia sac, it can cause varying degrees of intestinal obstruction. Once an incision occurs, it not only leads to the obstruction of blood supply to the intestinal loops in the hernia sac, causing strangulation, necrosis, or perforation, but also compresses the superior (inferior) mesenteric arteries and veins located at the anterior margin of the hernia ring, which in severe cases can obstruct the blood supply to the intestinal tract outside the hernia sac, even leading to ischemia and necrosis.

　　Patients may have the manifestations of long-term incomplete small bowel obstruction, such as recurrent intermittent, spastic abdominal pain, trunk straightening or overextension, and exacerbation after eating, accompanied by a history of nausea, vomiting, and bloating; or an acute intestinal obstruction may suddenly occur on this basis, which is a common complication of para-duodenal hernia. Once incarceration occurs, it not only leads to circulatory obstruction of the intestinal loops within the hernia sac, but also causes strangulation, necrosis, or perforation, and also compresses the superior (inferior) mesenteric arteries (veins) in front of the hernia ring mouth, which may obstruct the blood supply of the hernia sac exterior intestinal tract in severe cases, even leading to ischemia and necrosis.

　　The patient's clinical manifestations are not only related to the presence of small bowel obstruction, but also closely related to the degree of intestinal obstruction, whether there is incarceration and strangulation. The most common symptoms and signs are those of complete or incomplete small bowel obstruction.

　　Some patients may have no obvious symptoms, but most present with long-term incomplete small bowel obstruction, such as recurrent intermittent, spastic abdominal pain, lasting for several minutes or hours, straining, trunk straightening or overextension, and exacerbation after eating. These symptoms may be accompanied by nausea, vomiting, and bloating. The condition may resolve spontaneously without treatment, but repeated episodes are common, and often accompanied by postprandial nausea, vomiting, and bloating.

　　Once the obstruction turns into complete obstruction or even intestinal strangulation, persistent spastic abdominal pain may occur, accompanied by intermittent exacerbation, frequent, severe bilious vomiting. For most of the small intestine located within the hernia sac, there is not much small intestine at the proximal end of the obstruction, so bloating is not obvious. The abdomen can be palpated for a mass, the shape and size of which vary with the amount of intestine herniated. The mass has a tympanic percussion sound, slight tenderness, and can hear a high-pitched bowel sound. When the intestine is strangulated, the tenderness is obvious, the bowel sound disappears, and the patient may appear systemic toxic symptoms.

　　1. Do not drink alcoholic beverages for a long time, quit smoking and drinking habits, do not overeat pickled vegetables, sour, spicy and刺激性 food, and do not eat moldy food. It is more important for those with chronic pharyngitis to develop good dietary hygiene habits, such as eating less meat and more vegetables, and eating more fresh fruits and vegetables.

　　1. Do not drink alcoholic beverages for a long time, quit smoking and drinking habits, do not overeat pickled vegetables, sour, spicy and刺激性 food, and do not eat moldy food. It is more important for those with chronic pharyngitis to develop good dietary hygiene habits, such as eating less meat and more vegetables, and eating more fresh fruits and vegetables.

　　First, X-ray examination

　　1. Abdominal radiography or plain film:Visible twisted small intestine on the left or right side, intestinal dilatation with gas or fluid accumulation, and other signs of intestinal obstruction.

　　2. Gastrointestinal barium enema:It is helpful for the diagnosis of para-duodenal hernia, suitable only for patients without symptoms and signs of intestinal obstruction, typical imaging:

　　(1) Mass-like small intestinal loops are aggregated on the left or right side of the abdomen, and the intestines are not easy to separate. When the patient's position is pushed or changed, the small intestinal mass does not move, as if it is placed in a bag.

　　(2) Barium passes slowly through the small intestine; there are few small intestinal loops in the pelvic cavity, the terminal ileum is in a normal position, and the position of the colon and stomach is often changed. The characteristic imaging of a right-sided duodenal hernia: the small intestine is aggregated into a mass (hernia), located in the right abdomen. When the patient is standing, the stomach often hangs down to the left of the small intestinal mass (hernia), with the descending colon on its left, the ascending colon can be on its right, rear, front, or oblique left front. The imaging of a left-sided duodenal hernia: the small intestine is aggregated into an oval hernia and located in the left abdomen, with the stomach often crossing over the small intestinal mass (hernia) above, with a clear band between them, the ascending colon on its right, and the descending colon in front, left, or rear.

　　3. Selective mesenteric angiography:A right-sided duodenal hernia shows that the jejunal artery, although originating from the left side of the superior mesenteric artery, runs in the opposite direction, towards the small intestine. A left-sided duodenal hernia shows that the superior mesenteric artery remains at the same position at the root, but the jejunal artery enters the descending colon behind the herniated intestinal loops accompanying the hernia, and it can also be seen that the proximal jejunal artery runs in an internal posterior direction along the intestinal loops.

　　4. CT scan:A left-sided duodenal hernia may have a wrapped mass of intestinal loops between the stomach and pancreas, at the level of the Treitz ligament or behind the pancreas. The wrapped loops lack the finger-like gaps between normal intestinal loops, and visible dilated intestines and liquid-air levels can be seen. A right-sided duodenal hernia can be seen in the right middle abdomen with dilated intestines and liquid-air levels, and the superior mesenteric artery posterior to the jejunal and ileal arteries.

　　2. Ultrasound examination:

　　Visible clear boundary echo, with or without intestinal peristalsis, the tubular or cystic shape of the mass internally changes with time and diet.

　　1. Foods that are good for the body with duodenal hernia:

　　Pay attention to a light diet. In the first few days after surgery, adjust the diet according to individual conditions, mainly with liquid and semi-liquid foods, and eat more high-protein foods to promote wound healing. Supplement a variety of vitamins, eat more fresh vegetables and fruits. You can eat various lean meats, milk, eggs, and other protein-rich foods.

　　2. Foods to avoid with duodenal hernia:

　　Avoid overly greasy foods; foods such as preserved bean curd, scallions, chili peppers, chives, etc. are not conducive to wound healing as they are prone to cause infection.

　　(The above information is for reference only, please consult a doctor for details)

　　Asymptomatic duodenal hernias are often found during other surgeries, such as when the position of the colon is normal or altered, and part or most of the small intestine is enclosed in a sac-like capsule formed by the mesocolon. This can be diagnosed as a duodenal hernia, and the intestinal loop should be复位 and the hernial ring closed for treatment.

　　1. Classification during surgery:Judgment of left or right duodenal hernia based on pathological characteristics:

　　1. The hernial ring is located on the right side of the abdomen or opens to the right, and the anterior wall vessels are the inferior mesenteric artery, which is a left-sided duodenal hernia.

　　2. If the hernia ring orifice is on the left side of the abdomen or opens to the left, and the blood vessels on the anterior wall are the superior mesenteric artery, it is a right-sided paraumbilical hernia.

　　Two, Surgical Principles:For patients with long-term incomplete small bowel obstruction due to paraumbilical hernia, surgical treatment should be considered after diagnosis, and emergency surgery should be performed for those with acute intestinal obstruction. The principle of surgery is: reposition the intestinal loops, appropriately treat the herniated intestines, and close the hernia ring orifice.

　　Three, Surgical Method

　　1. Repositioning of the intestinal tract and loops:For the small intestinal hernia with few herniated contents and a small hernia mass, the repositioning of contents is relatively easy. If there is a large amount of herniated small intestine and it is incarcerated in the hernia sac, and the manual repositioning is difficult, carefully dilate the hernia neck and try to reposition; if there is still difficulty, carefully avoid the mesenteric vessels in front of the hernia sac, incise the hernia neck, and enlarge the hernia ring to facilitate the repositioning of the intestine from the hernia sac. To prevent mesenteric vessel injury, incise the hernia sac in the avascular area on the anterior wall of the hernia sac, extract the intestine, and perform incision and decompression to facilitate the repositioning of the intestine.

　　2. Treatment of the intestine:After the hernia sac's intestinal loops are repositioned, appropriate treatment can be given as necessary: ① If there is torsion, it should be relieved; ② Severe adhesions can be loosened, and enterostomy can be performed if necessary to avoid postoperative recurrence of intestinal obstruction; ③ If intestinal strangulation and necrosis have occurred, then intestinal resection and anastomosis should be performed.

　　3. Closing the hernia orifice:The left iliac hernia can first incise the lateral peritoneum of the descending colon on the side from the splenic flexure to the sigmoid colon; free the descending colon; incise the hernia sac along the long axis of the colon, turn the descending colon to the right, and clearly expose the hernia ring mouth. Incise part of the peritoneum around the hernia ring edge. Pay attention not to damage the inferior mesenteric vessels, reposition the hernia contents, and then close the hernia orifice, and fix the descending colon to the left posterior abdominal wall.

　　The right iliac hernia can incise the lateral peritoneum of the ascending colon on the side, turn the ascending colon to the left side of the abdominal cavity, place most of the duodenum, jejunum, and ileum on the right side, and place the terminal ileum, cecum, and colon on the left side of the median line, making the hernia sac part of the peritoneal cavity, thus effectively eliminating the hernia ring and completely repositioning the herniated small intestine. The superior mesenteric artery and its branches to the cecum and ascending colon are located on the anterior wall of the hernia sac, and the hernia sac should not be incised at this location to avoid injury to these blood vessels.