Chyloperitoneum

　　1. Etiology

　　The etiology of chyloperitoneum is complex, and it can be divided into congenital chyloperitoneum and acquired chyloperitoneum.

　　Congenital chyloperitoneum is caused by congenital abnormalities of abdominal lymphatic vessels, that is, incomplete development, absence, or stenosis of the thoracic duct, mesenteric lymph trunk, or cisterna chyli, leading to increased pressure in the intestinal lymphatic vessels, dilation, and rupture, or congenital fissures.

　　Acquired chyloperitoneum can be caused by trauma or surgical injury to the lymphatic trunk, leading to the occurrence of chyloperitoneum; intra-abdominal infection, especially post-infection of mesenteric lymph node tuberculosis or tuberculous peritonitis, can lead to chyloperitoneum; tumors or fibrous bands can compress the lymphatic vessels, causing distal lymphatic stasis, dilation, rupture, and the formation of chyloperitoneum.

　　2. Pathogenesis

　　Fats in food are broken down into fatty acids and monoglycerides through digestion. After being absorbed by the intestinal mucosal epithelial cells, they are synthesized into triglycerides by the body, and then enter the lymphatic vessels in the form of chylomicrons, which constitute the main component of chyle. Chyle flows into the cisterna chyli through the mesenteric lymphatic vessels, and then merges into the thoracic duct, and finally enters the cervical subclavian vein. Therefore, the lymph in the small intestinal lymphatic vessels, cisterna chyli, and thoracic duct is a white, odorless, alkaline reaction, with a specific gravity of 1.010-1.021. After standing, it can be divided into three layers: the upper layer is creamy, the middle layer is watery, and the lower layer is a white precipitate. The white blood cell count is about 5×109/L, mainly lymphocytes, and no bacterial growth is found in culture.

　　Chyle leakage into the abdominal cavity stimulates the occurrence of aseptic chemical inflammation changes in peritonitis, causing congestion, edema, and hypertrophy of the peritoneum and mesentery. The serous membrane under the intestinal wall is full of white, fine, curved chyle tube stripes, and the intestines become pale. Histological examination: peritoneum thickening, fibrous tissue hyperplasia, covered with a layer of inflammatory exudate, dilated, congested, and hemorrhagic blood vessels, and scattered chronic inflammatory cell infiltration, granulation tissue formation, showing chronic proliferative peritonitis changes.

　　Chyle is rich in nutrients, and prolonged and large-scale loss can lead to hypoproteinemia in the body and is prone to secondary bacterial infection. In addition to a few cases where the focus is localized and a leak can be found to be sutured, the effect of surgery is poor. Those caused by lymph node tuberculosis should be actively treated with anti-tuberculosis therapy. For lymphosarcoma or Hodgkin's disease with chyle ascites, radiotherapy may sometimes be effective. Chyle ascites secondary to trauma may gradually heal on its own and generally does not require surgical treatment. Some believe that a low-fat diet can be adopted for chyle ascites, and medium-chain triglycerides can be used to replace the fat consumed in daily life, which can improve symptoms. There are also reports of the application of peritoneal-cavernous venous shunt surgery (LeVeen tube) for the treatment of chyle ascites, which has achieved good results.

　　1. Acute peritonitis type

　　Rare, onset more than 4-6 hours after a large meal, especially after a fatty meal, due to the sudden and rapid entry of chyle into the abdominal cavity, causing acute chemical peritonitis. It is manifested as acute abdominal pain, initially widespread in range and location, sometimes as colic, and gradually intensified, accompanied by nausea, vomiting, abdominal distension, generalized or localized tenderness, often localized tenderness and muscle tension in the lower right or left abdomen, early hyperactive bowel sounds, and late decreased bowel sounds. It is often misdiagnosed as acute appendicitis or perforation of peptic ulcer disease.

　　2. Chronic peritonitis type

　　Chyle slowly leaks into the abdominal cavity, causing mild stimulation of the peritoneum, and the inflammatory reaction is also mild, with no obvious symptoms of peritoneal stimulation. It is manifested as gradual distension of the abdomen, weight loss or no increase, chyle diarrhea, hypoproteinemia, and malnutrition. In severe cases, it can affect respiration and circulatory function. Abdominal examination may show distension, varicose veins of the abdominal wall, mobile dullness on percussion, positive fluid tremor, and some may show scrotal effusion or edema of the scrotum and lower limbs.

　　The etiology of chyle ascites is complex, including congenital chyle ascites and acquired chyle ascites. Therefore, in terms of prevention, early prevention and treatment of the primary disease can play a certain role in prevention and treatment.

　　Firstly, abdominal puncture is performed to draw chyle-like ascites for examination.

　　1. Nature of ascites

　　Creamy white, alkaline, specific gravity 1.010～1.021, stratification occurs after standing; Sudan fat staining shows a positive reaction.

　　2. White blood cell count and classification

　　The white blood cell count in ascites is approximately 5×109/L, mainly composed of lymphocytes.

　　3. Bacteriological examination

　　No bacterial growth.

　　Second, imaging examination

　　1. Abdominal B-type

　　Ultrasound examination can detect a large amount of ascites.

　　2. Lymphangiography

　　Not only can it determine the cause, but it can also determine the location and extent of the lymph fistula.

　　For chyle ascites, provide a diet low in fat, medium-chain fatty acids, high in protein, and rich in vitamins. It is advisable to consume nutritionally rich, easy-to-digest, light foods, eat more fruits and vegetables, and drink plenty of water. Avoid spicy foods. Avoid greasy and rich foods.

　　First, treatment

　　1. Conservative treatment

　　(1) Diet therapy: Initially, provide a diet low in fat, medium-chain fatty acids, high in protein, and rich in vitamins, and try to reduce the intake of long-chain fatty acids. Since fat-rich diets can promote the leakage rate of chyle, which is not conducive to the healing of the fistula.

　　Medium-chain fatty acids, after being absorbed by the small intestinal mucosa, can be transported directly into the portal vein without passing through the intestinal lymphatic system. Therefore, medium-chain fatty acids not only can supplement nutrition but also can reduce the leakage of chyle.

　　(2) Fluid aspiration therapy: Abdominal puncture and fluid aspiration therapy is an important measure to relieve respiratory difficulty and reduce peritoneal irritation. Aspiration should be made to remove as much chyle as possible. Generally, fluid aspiration is performed once every 1 to 2 weeks, depending on the speed of chyle exudation, and some cases may gradually decrease ascites and be cured.

　　2. Surgical treatment

　　The purpose of the surgery is to relieve the cause, ligate lymphatic fistulas, or perform shunt surgery. For acute chyle ascites, traumatic chyle ascites, and patients with obvious primary diseases, such as chyle ascites caused by tumors, as well as those who have been treated conservatively for 3 to 4 weeks without effect or with worsening condition, surgical treatment should be performed as soon as possible.

　　(1) Surgical treatment to relieve the cause: Chyle ascites may be caused by inflammation, tumor, or fibrous bands compressing the lymphatic trunk. The surgery should involve the removal of tumors and the relaxation of bands to relieve compression. Ma Chi et al. reported a case of acute suppurative lymphadenitis rupture complicated with acute chyle peritonitis, where 1200ml of milky fluid was seen in the peritoneal cavity during surgery, and the ascites chyle test was positive. There were 4 enlarged lymph nodes in the terminal ileum mesentery, one of which had ruptured, and it was removed, resulting in recovery and discharge. In another case, a lymphangial cyst of the small intestinal mesentery ruptured and was complicated with chyle peritonitis. The ruptured collapsed cystic mass was surgically removed, and an abdominal drain was placed, resulting in cure.

　　(2) Suturing and ligating chyle fistula: In some cases, during surgery, a cleft can be seen near the root of the mesentery on the posterior abdominal wall, with chyle continuously leaking out of the fistula. The cleft should be sutured and ligated, and an abdominal drain should be placed. Among the 19 cases of surgical treatment collected by the author, 9 cases found the cleft and were cured by suture and ligation. To find the cleft more easily, some people inject Evan blue as a lymphatic tract indicator into the root of the mesentery during surgery to help locate the lymphatic tract cleft. Some people also consume a fat-rich diet 2 to 5 hours before surgery, feeding milk containing Sudan black, which can help locate the cleft. Some people have observed that the basic chyle flow rate is an average of 1ml/(kg·h), and the outflow rate after a fat meal can reach up to 200ml/h.

　　(3) Shunt surgery: Shunt surgery can be performed for those who cannot find the cause and foramen during surgery. The most commonly used shunt surgeries include:

　　① Abdominal great saphenous vein shunt surgery: It is to cut the femoral triangle, free the great saphenous vein, ligate its branches, free the length 12-15cm, then cut and ligate the distal end, make a hole at the lowest part of the abdomen, pull the proximal end of the great saphenous vein into the abdomen, and anastomose with the peritoneum.

　　② Abdominal venous shunt surgery: It is to place the Leveen tube with a one-way check valve, one end left in the abdomen, and the other end extracted from the abdomen through the great saphenous vein and placed into the iliac vein, or directly placed into the internal iliac vein within the abdomen, above the diaphragm level or to the right atrium. The one-way valve keeps the pressure between the vein and the abdomen at 0.294-0.490kPa (3-5cmH2O), so that when the abdominal pressure increases, chylous fluid can directly flow into the vein, establishing a new balance in the chylous circulation.

　　③ Lymph node venous shunt surgery: Some reports have shown that by cutting the enlarged lymph nodes horizontally or vertically, the lymphatic vessels entering the lymph nodes are retained, and then the cut surface of the lymph nodes is anastomosed with the inferior vena cava or iliac vein or its branches, thereby achieving cure.

　　In addition, abdominal drainage can also be performed for those who cannot find the cause and foramen. Conservative treatment can also be continued after surgery and can be cured.

　　Second, prognosis

　　This disease can be cured in most cases with timely and correct treatment, with good short and long-term efficacy, and very few recurrences. Among the 21 cases we collected, 19 were cured, 2 died, 1 died 2 months after the abdominal great saphenous vein bypass operation due to chylous ascites refusing treatment; and the other 1 died due to sepsis and multi-organ failure because the foramen was not found during surgery, and 75% alcohol was used to wipe the root of the mesentery.

　　Someone collected literature reports on 92 cases of chylous ascites in children, 16 deaths (17%), the mortality rate is related to the cause of the disease. The mortality rate of idiopathic chylous ascites is the highest, with 12 deaths in 53 cases (22.6%), and all the children who died did not receive special treatment, or only underwent peritoneal puncture, or laparotomy, and did not receive low-fat, high-protein diet.