阿米巴肝脓肿

　　Amoebic liver abscess is caused by the tissue-destroying ameba. Some form during the amebic dysentery stage, while others occur several weeks or months after dysentery, and some can last for up to twenty or thirty years. When people ingest food or water contaminated with amebae cysts after digestion by gastric juice, the protozoa are released in the intestines and multiply in large numbers, invading the colonic mucosa to form ulcers, which are common in the cecum and ascending colon. The ameba protozoa parasitizing the colonic mucosa secrete tissue-destroying enzymes, digest and dissolve the small veins on the intestinal wall, and then the protozoa invade the veins and flow into the liver with the portal vein blood. Some surviving protozoa reproduce in the liver, dissolve the liver tissue, and form abscesses.

　　Pathogenesis

　　Amoebic colitis patients, due to colonic ulcers, the trophozoites destroy the vascular wall, and the trophozoites enter the blood vessels and flow into the portal vein to reach the liver, but they can also directly invade the liver through the intestinal wall or reach the liver via the lymphatic system. The sinusoids of the liver lobules play a filtering role, and the protozoa remain at the terminal end of the microV. If the number of侵入 is small and the host is healthy, the protozoa can be eliminated without causing any liver damage. However, if a large number of protozoa invade, some can survive, and the surviving protozoa can reproduce within the liver tissue. Due to the large-scale reproduction of the protozoa, it can lead to the栓塞 of the sinusoids, resulting in ischemic necrosis of the liver tissue and the formation of small abscesses. On the other hand, the protozoa can enter surrounding tissues, causing necrosis and liquefaction of the liver tissue. As time goes by, the abscesses gradually expand outward, and the abscesses fuse with each other, eventually forming liver abscesses that can be detected clinically. Since the vermiform appendix and ascending colon are prone to amoebic colitis, and the right lobe of the liver receives blood from the cecum and ascending colon, the vast majority of the disease locations are located in the right lobe of the liver, especially the top of the right lobe.

　　阿米巴肝脓肿是溶组织阿米巴滋养体从肠道病变处经血流进入肝脏，使肝发生坏死而形成的，一般病程较长，患者全身情况较差，并且容易并发一些并发症，主要为脓肿向周围组织穿破及继发细菌感染。

　　阿米巴肝脓肿可向周围器官穿破，右叶脓肿向上可穿过膈肌形成脓胸或肺脓肿，穿破至支气管造成胸膜-肺-支气管瘘；向下可至大肠、肾脏、腹腔；向左还可穿破胃部。左叶脓肿可穿破至心包或腹腔、胸腔引起心包炎或腹膜炎、胸膜炎。除穿破至胃肠道或形成肝-支气管瘘外，预后大多恶劣。

　　慢性阿米巴肝脓肿、阿米巴肝脓肿穿刺容易引起继发细菌感染，出现感染时患者可有寒战、高热较明显，毒血症加重，血白细胞总数及中性粒细胞均显著增多。脓液呈黄绿色，或有臭味，镜检有大量脓细胞，但细菌培养阳性率不高。

　　阿米巴肝脓肿的发展过程一般比较缓慢，急性阿米巴肝炎期较短暂，如不及时治疗，继之为较长时期的慢性期。其发病可在肠阿米巴发病数周至数年后，甚至可长达30年后才出现阿米巴性肝脓肿的报道。过去病史中约有60％以上的病人有脓血便等痢疾病可查。

　　1、急性肝炎期

　　在肠阿米巴过程中，可出现肝区疼痛、肝脏肿大、压痛明显，体温升高(体温持续在38～39℃)、脉速和大量出汗等症状，此时如能及时正确治疗，炎症可得到控制，避免脓肿形成。

　　2、肝脓肿期

　　临床表现取决于脓肿的大小、部位、病程长短及有无并发症等，但大多数病人起病较缓慢，病程较长，此期间主要表现为发热、肝区疼痛、肝脏肿大等。

　　(1) Fever: Most cases have a slow onset, with persistent fever, body temperature ranging from 38～39℃, most commonly with remittent or intermittent fever; chronic liver abscess may have a normal or low-grade fever; if secondary bacterial infection or other complications occur, the body temperature may rise above 40℃, often accompanied by chills or shivering; the body temperature is usually lower in the morning and higher in the afternoon.

　　(2) Liver pain: Persistent pain in the liver area, occasionally with sharp or severe pain, which may worsen with deep breathing, coughing, or changes in body position. If the abscess is located at the top of the right diaphragm, the pain may radiate to the right scapula or right back.

　　(3) Local edema and tenderness: Larger abscesses may cause bulging in the right lower chest and upper abdomen, fullness between the ribs, local skin edema and luster, possible widening of the intercostal spaces, marked local tenderness or liver area percussion pain, and possible tenderness and muscle tension in the upper right abdomen. Sometimes, an enlarged liver or mass may be palpated.

　　(4) Liver enlargement: The liver often presents with diffuse enlargement, with marked localized tenderness and percussion pain at the site of the lesion. The enlarged liver can be palpated below the right costal margin, with a dull, rounded lower edge, a full feeling, moderate consistency, marked tenderness, and often accompanied by abdominal muscle tension. Some patients may develop right pleural effusion.

　　Amoebic liver abscess is more common in warm and tropical regions, especially in tropical and subtropical countries. According to clinical data, 1.8％～20％ of patients with intestinal amoebiasis develop liver abscesses. If not treated promptly, this rate can reach up to 60％.

　　This disease is more common in middle-aged and young male adults aged 20～50. Among the 4819 cases reported in China, 90.1% are male and 9.9% are female. It is more common in rural areas than in urban areas. Amoebic liver abscess has a long course, and patients often have anemia and malnutrition. Nutritional and systemic supportive therapy should be strengthened, providing a diet high in carbohydrates, proteins, vitamins, and low in fat. Plasma and albumin may be supplemented if necessary, and antibiotics should be administered simultaneously.

　　To prevent the occurrence of amoebic liver abscess, attention should be paid to personal and dietary hygiene. Wash hands before and after meals, drink boiled water, and wash raw vegetables and fruits thoroughly before eating, and make appropriate disinfection treatments, such as soaking in vinegar or potassium permanganate.

　　Strengthen physical exercise, improve dietary structure, and enhance the body's ability to resist diseases. Patients diagnosed with amoebic dysentery should be treated as soon as possible, taking drugs with anthelmintic effects, such as metronidazole and ipecac alkaloid hydrochloride, to prevent the occurrence of amoebic liver abscess. Traditional Chinese medicine such as Brucea javanica and Pulsatilla chinensis also have preventive and therapeutic effects on acute and chronic amoebic enteritis.

　　For individuals entering the epidemic area, one of the following drugs may be taken if necessary: metronidazole 0.2～0.4g, trichlorosulfan 0.5g, diiodoquin 0.6g, 1～2 times/day.

　　Amoebic liver abscess requires many examinations, among which the main ones are:

　　1. Blood count examination

　　The total white blood cell count usually increases in the early stage (13～16)×10^9/L, and often decreases below normal in the later stage. Neutrophils account for about 80%, and this percentage is higher in cases with secondary infection. Hemoglobin levels decrease, and the erythrocyte sedimentation rate may accelerate.

　　2, Liver function test

　　ALT and most other items are within the normal range, but the activity of serum cholinesterase is reduced significantly.

　　3, Gene detection

　　Using the molecular weight of 30×10^3 protein coding gene primer of the invasive ameba, it can detect its gene fragment from the abscess fluid by PCR method, with sensitivity and specificity of 100%.

　　4, Ultrasound examination

　　The diagnostic accuracy of B-ultrasound imaging can reach more than 90%, showing a liquid shadow in the liver area, and at the same time, it can understand the size, range, and number of the abscess, which is helpful for guiding puncture qualitative diagnosis and treatment.

　　5, X-ray examination

　　Right diaphragmatic elevation, restricted movement, local prominence; sometimes there may be pleural reaction or effusion, lower lobe pneumonia or discoid atelectasis, etc.; occasionally, a gas-liquid surface in the abscess cavity may be visible on plain films; irregular radiolucent liquid-air shadows in the liver area have special diagnostic significance, and contrast agents can show the size of the abscess cavity.

　　6, CT

　　The liver abscess area shows uneven or uniform low-density area, after contrast agent enhancement, the peripheral area of the abscess shows a ring-shaped density increase band, and there may be a gas-liquid surface in the abscess cavity. The density of the cyst is similar to that of the abscess, but the edge is smooth, and there is no congestion band around it; the CT value of liver tumors is 35 to 50Hu, significantly higher than that of liver abscess.

　　7, Serological examination

　　Using amebic pure culture antigen for serological reactions, its specificity is very high, such as indirect hemagglutination test, indirect fluorescent antibody test, and ELISA test, the positive rate can reach 95% to 100%. Therefore, it has great auxiliary diagnostic value for amoebic liver abscess, and those with negative results can basically be excluded from the disease.

　　Amoebic liver abscess is also one of the liver diseases, therefore, nourishing and protecting the liver is also one of the health measures.

　　The first choice of food for nourishing the liver is grains, such as glutinous rice, black rice, sorghum, and millet; followed by dates, longan, walnuts, chestnuts; and there are also meat and fish such as beef, pork stomach, crucian carp, etc., which also have a health-preserving effect on the liver.

　　1, Soybeans and soy products

　　It is rich in protein, calcium, iron, phosphorus, vitamin B, moderate amounts of fat, and a small amount of carbohydrates, which is very beneficial for liver repair.

　　2, Seafood

　　For example, whitebait, yellow croaker, silver croaker, and shellfish such as oysters and crabs, can enhance immune function, repair damaged tissue cells, and not be invaded by viruses. However, proper selection and cooking are necessary, otherwise food poisoning may occur. Steaming should be heated for more than half an hour at 100 degrees. If allergic to seafood, avoid eating, and eat more mushrooms, silver ear, seaweed, and laver, etc.

　　3, Watermelon

　　It has the effects of clearing heat and detoxifying, relieving thirst, diuresis, and hypotension, and is rich in a large amount of sugar, vitamins, and proteases. Proteases can convert insoluble proteins into soluble proteins.

　　4, Foods rich in potassium

　　Seaweed, bran, wheat bran, apricot kernel, sugar, raisins, banana, plum, melon seeds.

　　5, Green tea

　　It is beneficial to the liver, with anticoagulant, anti-platelet adhesion and aggregation, reducing leukocyte decrease and promoting blood circulation to remove blood stasis. However, tea should be drunk at appropriate times and in moderate amounts, a cup not too strong in the morning, and the total amount of tea water should not exceed 1000 to 1500 milliliters per day. Stop drinking tea one hour before meals to avoid diluting stomach acid and hindering food absorption.

　　The course of amebic liver abscess is long, and the patient's overall condition is poor, often with anemia and malnutrition. Nutritional and systemic supportive therapy should be strengthened, and a diet high in carbohydrates, proteins, vitamins, and low in fat should be provided. Plasma and albumin can be supplemented if necessary, and antibiotics should be given at the same time. The main treatment measures are to use antiamoebic drugs, supplemented by puncture and drainage, and surgical treatment should be adopted if necessary.

　　1. Antiamoebic Drug Treatment

　　(1) Metronidazole: It is the first choice of drug, with high efficacy and low toxicity, and a short course of treatment. The antiparasitic activity and pharmacokinetic characteristics of the second-generation nitroimidazole drugs are the same as those of metronidazole, but the efficacy of treating abscesses is better than that of amebic enteritis due to its longer half-life. In Southeast Asia, short-term (1-3 days) treatment is used, and it can replace mebendazole.

　　(2) Chloroquine: has low toxicity, and after absorption, its concentration in the liver, lung, and kidney is 200-700 times higher than that in the blood, with good efficacy.

　　(3) Emetine (ipecac) or dehydroemetine (dehydroipecac).

　　2. Puncture and Drainage

　　If there is no significant improvement in symptoms after puncture and drainage, or if the abscess cavity is large or complicated with severe bacterial infection, puncture and drainage should be performed at the same time as the use of antiamoebic drugs. Puncture should be performed at the nearest site to the abscess cavity under B-ultrasound guidance and local anesthesia, with strict aseptic operation. In recent years, there has also been the practice of leaving a drainage tube in the abscess cavity, which has been effective, but it is better not to place a tube if there is no secondary bacterial infection. Treatment with puncture and drainage can be stopped when the patient's body temperature is normal and the abscess cavity has shrunk to only be able to extract 5-10ml of pus.

　　3. Antibiotic Treatment

　　When there is mixed infection, appropriate antibiotics should be used systemically according to the type of bacteria.

　　4. Surgical Treatment

　　In addition to drug treatment for amebic liver abscess, surgical drainage may be considered if the following conditions are present:

　　① If there is no improvement in symptoms after treatment with antiamoebic drugs and puncture and drainage;

　　② If the abscess is accompanied by secondary bacterial infection and cannot be effective after comprehensive treatment;

　　③ If the abscess is deep or not suitable for puncture and drainage due to its location;

　　④ If the abscess penetrates into the pleural cavity or abdominal cavity, and complications such as empyema or peritonitis occur;

　　⑤ If there is no effect after treatment with antiamoebic drugs for liver abscess in the left lateral lobe of the liver, and puncture may damage abdominal organs or contaminate the peritoneal cavity, postoperative treatment with antiamoebic drugs should continue.