Mesenteric hiatal hernia

　　Research has confirmed that the existence of mesenteric fissure is the anatomical basis for the occurrence of internal hernia. Mitchell and Watson each found 3 cases with ileocecal mesenteric fissure in 1000 and 1600 cadavers, respectively, but no internal hernia occurred before death. This indicates that although many individuals have mesenteric fissures, they do not necessarily form internal hernias. Only under the combined effects of intestinal peristalsis or abnormal peristalsis, and increased intraperitoneal pressure, etc., may internal hernia occur.

　　The presence of an abnormal fissure in the mesentery of the patient is one of the important causes of internal hernia. The formation of the mesenteric fissure can be due to congenital developmental abnormalities, or it can be caused by trauma or surgical errors, among which congenital developmental abnormalities account for the majority, especially in children. Some authors reported that in 99 cases of mesenteric fissure hernia, only 11 were acquired; another scholar reported that in 83 cases of mesenteric fissure hernia, 82 were congenital. Treves found a circular or oval area (Treves area) in the mesentery of the fetal ileocecal region, which is characterized by the absence of fat and visible blood vessels, and no branches of mesenteric lymphatic vessels, making it a high-risk area for mesenteric defects.

　　Under normal circumstances, there is no pressure difference within the abdominal cavity, as the mesentery is relatively long, the intestinal tract can enter the fissure during natural peristalsis; when there are abnormal peristalsis or overeating, the weight of some parts of the intestinal tract increases or the body position changes suddenly, and the intraperitoneal pressure increases, the intestinal tract is more likely to slip into or protrude into the mesenteric fissure, forming an internal hernia, leading to incomplete or complete intestinal obstruction. The intestine herniated into the mesenteric fissure can be spontaneously extruded with peristalsis, or occur repeatedly, causing intermittent paroxysmal or chronic abdominal pain. The edges of the mesenteric fissure become thickened due to repeated herniation and extrusion of the intestine, local edema, and hyperplasia.

　　When the intra-abdominal pressure suddenly increases, a large amount of small intestine can be squeezed into the defect, and the defect expands passively and then retracts, preventing the herniated small intestine from returning, leading to an incision and causing abdominal colic. The reflex of abdominal pain causes abdominal wall muscle spasm, exacerbating the incision. Due to the lack of support from the hernial sac, the incarcerated intestinal tube can quickly develop circulatory disturbances. The herniated intestinal tube can also twist due to abnormal peristalsis, causing the intestine to swell due to gas and fluid accumulation, further accelerating the ischemia and necrosis of the incarcerated intestinal tube. Due to the compression of the incarcerated intestinal tube and its mesentery, blood return is obstructed, leading to edema and thickening of the intestinal wall and mesentery. The thickened intestine and mesentery further compress the vessels around the hernial ring (the free margin of the mesenteric defect), causing ischemia and necrosis of the corresponding mesenteric segment of the intestine. Even without strangulation, the herniated intestinal tube may cause ischemia and necrosis. If not treated promptly, patients may experience toxic shock and dysfunction of the respiratory and circulatory systems due to significant fluid loss, intestinal distension, infection, and absorption of toxins.

　　Therefore, the mesentery of the small intestine may sometimes have congenital defects or clefts, and the transverse mesocolon may occasionally have defects. Small intestinal loops can pass through this hole and cause obstruction or incarceration. Ischemia of the intestinal tube during fetal development may be related to congenital mesenteric defects, which are more common in infants with intestinal atresia.

　　According to Williamson's report, the incidence of intestinal necrosis in mesenteric defect hernia is about 50%. It is manifested by asymmetric abdominal distension and tender abdominal mass. Marked abdominal tenderness, rebound pain, and muscle tension are prominent, with positive mobile dullness in the abdomen. Peritoneal puncture may yield hemorrhagic effusion, and in severe cases, toxic shock symptoms may appear.

　　Clinical symptoms and signs vary depending on the size of the mesenteric defect (hernial ring), the location, quantity, whether complete intestinal obstruction occurs, and whether strangulation occurs.

　　If the herniated enteric loop does not become incarcerated or strangulated, clinical symptoms are usually mild. However, due to the repeated herniation and retraction of the enteric loop, traction and irritation on the mesentery or intestinal tube may occur, leading to intermittent paroxysmal abdominal pain or chronic abdominal pain in some patients. The pain is often located in the upper abdomen or around the umbilicus, with a few cases accompanied by vomiting and constipation. Most patients do not show significant abdominal distension and lack signs of mechanical intestinal obstruction such as the presence of intestinal loops, intestinal peristalsis, and hyperactive bowel sounds.

　　Once an enteric loop herniates and becomes strangulated, clinical symptoms and signs of complete intestinal obstruction appear, characterized by sudden, persistent pain in the upper abdomen or around the umbilicus, which intensifies intermittently. These are accompanied by nausea, vomiting, cessation of flatus and defecation, and abdominal distension, indicating strangulated intestinal obstruction. As the course of the disease progresses, due to significant fluid loss, infection, and poisoning, patients may exhibit profuse sweating, pale complexion, and acute diffuse peritonitis and toxic shock within a short period of time. In some cases, if the herniated enteric loop twists, asymmetric abdominal distension may occur, and a mass in the abdomen can be palpated. Marked abdominal tenderness, rebound pain, and muscle tension are prominent, with positive mobile dullness in the abdomen. Peritoneal puncture may yield hemorrhagic effusion.

　　In the case of an internal hernia in the transverse mesocolon, the small intestine herniated into the omental sac can return to the large abdominal cavity through the Winslow hole, the falciform ligament, and the gastrocolic ligament, or the weak area due to the abnormal 'course' of this intestinal segment, causing compression of the distal stomach, and the patient may appear symptoms similar to chronic ulcer disease or pyloric obstruction.

　　1. Develop good living habits.

　　2. Maintain a good mood, stable emotions, and healthy eating habits, eat more fruits and vegetables, etc., to enhance self-immunity.

　　3. People who must work in heavy smoke should try to protect themselves, such as wearing masks, going out to breathe some fresh air regularly, and at least doing one check-up a year.

　　4. Stay away from smoke, alcohol, drugs, radiation, pesticides, noise, volatile harmful gases, toxic and harmful heavy metals, etc.

　　The chemical examination of mesenteric hernia includes laboratory examinations and auxiliary examinations.

　　Laboratory examinations include:

　　1. Hemoglobin and hematocrit can increase due to dehydration and blood concentration.

　　2. A significant increase in white blood cell count and neutrophils suggests the occurrence of intestinal strangulation.

　　3. Serum electrolytes (K, Na, Cl), blood gas analysis, and other measurements can reflect the situation of water, electrolytes, and acid-base balance.

　　Auxiliary examinations include:

　　1. Abdominal透视 or plain film. In the acute phase, it can show the manifestations of strangulated intestinal obstruction, such as a large amount of gas and fluid in the intestinal cavity, 'intestinal occlusion loop' shadow, and dense mass shadow (pseudo-tumor) shadow, but it generally cannot clearly identify the cause of the obstruction.

　　2. Mesenteric artery angiography. Selective mesenteric artery angiography can suggest the abnormal passage of related mesenteric blood vessels through the hernia ring and blood circulation conditions.

　　3. CT scan. It can show the location of intra-abdominal hernia, intestinal gas and fluid accumulation, thickening of the intestinal wall, and intestinal mass shadow.

　　It should be noted that mesenteric hernia should be distinguished from adhesive intestinal obstruction, intestinal volvulus, intussusception, mesenteric vascular thrombosis, gastric and duodenal ulcer perforation, acute necrotizing pancreatitis, acute appendicitis, and other surgical acute abdominal conditions.

　　The diet of patients with mesenteric hernia should be light. On the one hand, in the first few days after surgery, diet should be adjusted according to individual condition, mainly with liquid and semi-liquid foods, and eating more high-protein foods is beneficial to the recovery of the wound. On the other hand, it is necessary to supplement a variety of vitamins, and eat more fresh vegetables and fruits. It is recommended to eat various lean meats, milk, eggs, and other foods rich in protein.

　　Patients with intestinal mesenteric hernia should avoid greasy foods and should not choose foods such as preserved bean curd, scallions, chili peppers, chives, etc., which are not conducive to wound healing, as they are prone to cause infection.

　　Due to the difficulty in determining the diagnosis before surgery and the high incidence of intestinal strangulation and necrosis, the average mortality rate (Moch, 1958) is as high as 62%. Moreover, the only effective treatment for this disease is surgery. Therefore, for patients with intermittent, paroxysmal, chronic upper abdominal or umbilical pain history, the diagnosis should be considered as intestinal mesenteric hernia, and the surgical indication can be appropriately relaxed under the consent of the patient and family. If abdominal surgery is performed for other reasons, attention should be paid to exclude the existence of intestinal mesenteric hernia, and if an intestinal mesenteric hernia is found, it should be sutured and repaired to prevent the occurrence of intestinal mesenteric hernia in the future.

　　For patients seeking medical attention for acute intestinal obstruction and cannot exclude the possibility of intestinal mesenteric hernia, active preoperative preparation should be done, and early surgery should be performed to avoid intestinal strangulation, intestinal necrosis, and even life-threatening conditions.

　　The principle of surgery is to relieve obstruction and repair the hernia.

　　The precautions for surgery are as follows: 5 points

　　(1) Automatic复位 of herniated intestinal tube: In some intestinal mesenteric hernias, the herniated intestinal tube can automatically复位 or be explored, as unintentional traction of the intestinal tube may cause the herniated intestinal loop to automatically复位. Therefore, during surgery, careful inspection of each mesentery, omentum, and peritoneal recess should be performed to find and deal with the pathological factors causing obstruction as much as possible. It is imperative not to end the surgery in a hurry without finding the answer. Wang Xiaoxiang once reported a case of a 12-year-old male child who was admitted to the hospital and operated on due to paroxysmal abdominal pain for 7 days. On the second day after the operation, persistent abdominal pain appeared, accompanied by exacerbation, nausea, vomiting, and marked abdominal distension. X-ray examination diagnosed acute intestinal obstruction and reoperation. The second operation found a 2.5cm defect in the transverse colon mesentery, with about 80cm of small intestine herniated, and 15cm of ascending colon necrosis and perforation. The reason is that the first operation did not find the pathological factors causing intestinal obstruction, leading to the second occurrence and causing intestinal necrosis.

　　(2) Intestinal mesenteric hernia complicated with other abdominal abnormalities: Patients with intestinal mesenteric hernia may have congenital malformations of the gastrointestinal tract at the same time, such as malrotation of the intestine, small intestinal stenosis or atresia, intestinal duplication malformation, etc. Therefore, attention should be paid to the discovery of congenital malformations of the gastrointestinal tract during surgery, and as far as possible to deal with them at the same time if the condition permits, in order to avoid affecting postoperative recovery and the need for reoperation.

　　(3) Vitality judgment of incarcerated and strangulated intestinal tubes: The judgment of the vitality of the incarcerated intestinal loop is crucial for surgical management.

　　Method: Approximately 20cm of the proximal and distal ends of the herniated intestinal tube are pulled out, and their color, tension, and peristalsis are observed; the pulsation of the mesenteric vessels; whether the exudate in the hernia sac is turbid and has an odor, etc. If necrosis is suspected, an appropriate amount of 0.25% procaine 5-10ml can be injected into the root of the mesentery, and at the same time, the intestinal tube can be heated with warm saline to relieve the tension. It can also be temporarily placed in the abdominal cavity for observation for 15-20 minutes. If the intestinal tube turns red and the peristalsis and mesenteric artery pulsation recover, then the vitality is still good. For the intestinal tubes that cannot be judged after observation, it is better not to leave them.

　　(4) Treatment of hernia ring and protection of mesenteric vessels: For patients with good blood supply of the herniated intestinal loop, the hernia ring (mesenteric defect) can be expanded to relax and realign the incarcerated intestinal tract, and the hernia ring can be sutured and repaired. For patients with difficulty in realigning the herniated intestinal tract, the hernia ring can be expanded first and then tried to realign. If it is still difficult to realign the herniated intestinal loop after expanding the hernia ring, the herniated intestinal loop can be decompressed and realigned again to avoid the hernia ring from being too large and damaging the main mesenteric vessels. Since at least one side of the free margin of the hernia ring is formed by the branch of the superior mesenteric artery or inferior mesenteric artery, it is very easy to damage it when expanding the hernia ring. To prevent injury to the main mesenteric vessels, it is necessary to carefully identify and protect the main mesenteric vessels to avoid injury. It is forbidden to pull hard or blindly cut the edge of the hernia ring hole. If it is necessary to cut the mesentery to expand the hernia ring, it should be cut from the intestinal tract to the edge of the mesenteric defect, even if the vessels are injured, they are not the main mesenteric vessels.

　　For patients with necrosis and perforation of the herniated intestinal loop, if the overall condition of the patient allows, anastomotic resection of the intestinal loop should be performed in one stage, and then the hernia ring should be sutured and repaired. If there are too many herniated intestinal loops with necrosis and obvious expansion, and it is difficult to realign, the intestinal tube at the crack should be cut first, and the incarcerated intestinal tube should be decompressed and realigned, removed, and then anastomosis should be performed; to prevent the rupture of necrotic intestinal tube during realignment, which will worsen peritoneal contamination. When resecting the intestinal tube, it is as much as possible to tie the two ends of the necrotic intestinal tube with gauze first, so as not to allow the contents of the necrotic intestinal tube to flow into the adjacent intestinal tube, postoperative absorption, aggravate the symptoms of poisoning, and affect recovery. If the patient's condition is serious, a jejunostomy can be performed first, and then a second-stage intestinal anastomosis can be performed after the condition improves.

　　(5) Hernia ring suture: It is advisable to use non-absorbable suture for intermittent suture when suturing the hernia ring, and at the same time, pay attention not to pierce or tie off the superior mesenteric artery or inferior mesenteric artery at the free margin of the hernia ring.