Pediatric primary peritonitis

　　One, Etiology

　　Primary peritonitis is mostly caused by bacteria from other parts of the body entering the peritoneal cavity through the blood circulation, and a few children can also enter the peritoneal cavity and cause infection by ascending through the lymphatic system, gastrointestinal tract, and female reproductive system (in the prepubertal period, the local pH value and mucosa are suitable for bacterial growth). Nephrotic and liver disease children have a large amount of peritoneal fluid in the abdominal cavity, often infected due to low immunity and complement deficiency. The most common pathogenic bacteria in this disease are group A Streptococcus, Streptococcus pneumoniae, Enterococcus, Staphylococcus, and Escherichia coli.

　　Two, Pathogenesis

　　After bacteria enter the peritoneal cavity, they cause peritoneal congestion, edema, and exudation. The exudate contains a large number of neutrophils, necrotic tissue, bacteria, and coagulated fibrin, usually presenting as turbid exudate or thin purulent fluid. Due to the large amount of exudate and the relatively low content of fibrin, localized abscesses are rare. The pus from Streptococcus is thin and rarely produces fibrinopurulent adhesion. The pus caused by Staphylococcus, Escherichia coli, and Streptococcus pneumoniae is thicker and has more adhesions. After infection control, the pus is absorbed, and the fibrinopurulent adhesions in the peritoneal cavity are absorbed within a week. Some children may have pericardial damage or necrotic tissue in the abdomen, which may leave extensive and tenacious intestinal adhesions, becoming a potential factor for adhesive intestinal obstruction. Due to the edema of the intestinal wall stimulated by the exudate, intestinal peristalsis is suppressed, leading to intestinal distension and paralysis; a large amount of extracellular fluid exudation causes dehydration and electrolyte disorder, and in severe cases, it reduces the circulating blood volume, leading to circulatory failure; at the same time, a large number of bacteria and toxins are absorbed by the peritoneum, which can produce septicemia, bacteremia, or toxic shock.

　　1. Toxic shock:Its characteristics are high fever, vomiting, diarrhea, confusion, and rash, which can quickly progress to a severe and refractory shock.

　　2. Multiple organ failure:MSOF refers to the simultaneous or successive occurrence of acute dysfunction in two or more systems or organs during the process of acute diseases such as severe trauma, major surgery, severe infection, and shock. Among the many systems and organs such as the heart, lung, kidney, liver, brain, blood, and digestion, the lung is often the first to be damaged, followed by the kidney, liver, and brain, etc.

　　3. Late stage:It is easy to cause peritoneal adhesion, leading to complications such as adhesive intestinal obstruction.

　　1. Severe toxic symptoms:The child has severe systemic toxic symptoms, pale complexion, irritability, or listlessness, and is dull to external stimuli. Examination shows that the child is confused, with a body temperature as high as 40°C, a rapid and weak pulse. In small infants, the body temperature may be normal, and important signs include abdominal distension and the disappearance of bowel sounds. The child often has severe dehydration and toxic symptoms, but without obvious secondary peritonitis. In late cases, the general condition is poor, presenting with semi-comatose state, delirium, emaciated appearance, difficulty breathing, herpes on the lips, dry skin, and a severe state of dehydration. However, in cases treated with antibiotics in the early stage, symptoms are relatively mild, and the general condition is better. Nephrotic syndrome complicated with peritonitis is more common in school-age children, with generally mild illness and relatively mild toxic symptoms.

　　2. Gastrointestinal symptoms:Abdominal pain is often severe, affecting the entire abdomen, often worse in the lower abdomen, with frequent vomiting, vomiting food residue and bile. Initially, there may be occasional diarrhea, but later, due to abdominal distension and intestinal paralysis, constipation or inability to pass gas often occurs. In some cases, diarrhea or frequent urination may occur due to stimulation of the intestinal wall or pelvis. Sometimes, there may even be mucous bloody stools.

　　3. Signs:Abdominal distension, non-peritoneal type, with tenderness and muscle tension in the entire abdomen, but in infants and young children, the muscle tension is often not obvious. Abdominal tenderness, rebound tenderness, and muscle tension are not as obvious as secondary peritonitis. Palpation may present with tympany and mobile dullness. Abdominal fluid in large quantities may show signs of ascites, namely, the tremor transmission sign. Auscultation may show normal bowel sounds in the early stage, but later bowel sounds may diminish or disappear. Nephrotic syndrome complicated with peritonitis may present with sudden abdominal pain accompanied by fever, increased swelling of the abdominal wall and scrotum. Liver disease complicated with peritonitis may show dilated abdominal wall veins, and it is common to see redness and tenderness below the umbilicus. It is often suspected to be an ascending infection of the female reproductive tract. Abdominal pain and signs are most pronounced in the lower abdomen, and rectal examination may show tenderness in the rectovesical or rectouterine陷凹.

　　1. Regular physical examination:In order to achieve early detection, early diagnosis, and early treatment.

　　2. Do a good job of follow-up:To prevent the deterioration of the disease.

　　3. Vaccination:Children under 2 years of age and older children with nephrotic syndrome or chronic renal insufficiency (and chronic liver diseases with possible ascites) need to be revaccinated with pneumococcal vaccine.

　　4. Strengthen physique:Improve immunity: Pay attention to the combination of work and rest, participate in more physical exercises, and eat more fresh fruits and vegetables rich in vitamins.

　　1. Blood routine:The peripheral blood leukocyte count is much higher than that of general peritonitis, which can reach (20～40)×109/L (20,000～40,000/mm9), and neutrophils can increase to more than 90%.

　　2. Abdominal puncture fluid:If the ascites is cloudy, thin pus can be aspirated, and the smear shows a large number of pus cells. After Gram staining, diplococci or cocci can often be found; if ascites culture is positive, gynecological examination and transcervical puncture aspiration of pus may be necessary, and B-ultrasound and X-ray examination should be performed. X-ray abdominal film shows intestinal paresis (simultaneous colonic distension) and many scattered low tension liquid levels, and abdominal water phenomenon can be seen. Pay attention to the presence of free gas, and other examinations such as CT may be necessary to make a definite diagnosis.

　　1. Easy-to-digest foods that promote defecation. Such as vegetables: kelp, pork blood, carrots, etc.; fruits: hawthorn, pineapple, papaya, etc.; eat more fibrous foods such as various vegetables, fruits, brown rice, whole grains, and beans, which can help defecate, prevent constipation, stabilize blood sugar, and reduce blood cholesterol.

　　2. Choose vegetable oil, which is often cooked by boiling, steaming, cold dish, roasting, baking, pickling, and stewing; avoid high-cholesterol foods such as fatty meat, offal, fish eggs, and cream.

　　One, treatment

　　1. Non-surgical treatment

　　Primary peritonitis is relatively mild or nephrotic ascites complicated with peritonitis should mainly be treated by non-surgical methods, and most children can be cured. Non-surgical therapy should include 4 parts:

　　(1) Antibiotic treatment: Choose the appropriate high-dose antibiotic based on the results of abdominal puncture fluid smear or bacterial culture.

　　①Gram-positive bacterial infection: If the primary peritonitis pathogen is a single gram-positive bacterium, such as streptococcal and pneumococcal infection, penicillin is the first choice. Penicillin has a clear therapeutic effect on gram-positive bacteria, is inexpensive, and is more effective at high doses. However, patients with penicillin allergies and poor liver and kidney function should not use it, and some patients are resistant to penicillin. If allergic to penicillin, use erythromycin or cephalosporin. Treat staphylococcal infections with new penicillin or cephalosporin; treat Escherichia coli infections with ampicillin (ampicillin) or gentamicin.

　　② Mixed infection: If the primary peritonitis is a mixed infection, ceftriaxone (ceftriaxone) or ceftriaxone is selected. Ceftriaxone has a broad antibacterial spectrum and is effective against both Gram-positive and Gram-negative bacteria. The half-life is long at 12h, and it only needs to be injected intravenously once a day. It is effective for respiratory tract infections and has small toxic and side effects on the liver and kidneys. However, it is expensive, and it should be used with caution in patients with penicillin allergy. Some patients may develop resistance to ceftriaxone. Quinolone antibiotics are effective against both Gram-positive and Gram-negative bacteria and are especially effective for respiratory and urinary tract infections, with a low incidence of resistance. However, this class of drugs affects the development of children's bones and is not suitable for children. In summary, for primary peritonitis, high-efficiency, broad-spectrum, and low-side-effect antibiotics should be used. Nephrotic syndrome complicated with peritonitis can be cured with antibiotics and other therapies, and does not require surgical treatment.

　　(2) Supportive treatment: Fresh frozen plasma or fresh blood is given for extracorporeal nutrition support, as well as a large amount of various vitamins to improve the general condition.

　　(3) Correct dehydration and electrolyte imbalance.

　　(4) Continuous gastrointestinal decompression to relieve abdominal distension and allow the gastrointestinal tract to rest.

　　2. Surgical Treatment

　　For patients with primary peritonitis that does not respond to drug treatment or cannot exclude secondary peritonitis, early laparotomy should be performed. Although laparotomy has a certain misdiagnosis rate, it is still more beneficial than harmful for saving patients' lives. At present, the main treatment principle for primary peritonitis is surgical treatment, because surgery can confirm the diagnosis, exclude a part of secondary peritonitis (such as that caused by appendiceal perforation), and drain pus to reduce toxin absorption and improve symptoms of poisoning. The drained pus can be used for bacterial culture and drug sensitivity test to facilitate the selection of antibiotics. Preoperative preparation should be made according to the 4 items of non-surgical treatment.

　　II. Prognosis

　　The mortality rate is not high except for those not treated in time. If complications occur, the course of the disease will be prolonged, but the prognosis is generally good. At the same time, the prognosis should also be considered based on the evolution of the primary disease, such as nephrotic syndrome and the evolution of chronic liver disease.