The cancer antigen CA125 has been widely used in the diagnosis of malignant tumors, especially ovarian tumors. Recent studies have shown that CA125 has some reference value in the diagnosis, treatment and follow-up of tuberculous peritonitis, and the relevant literature is reviewed as follows. 1.CA125 In 1981, Bast et al. were the first to apply CA125 monoclonal antibody to confirm that ovarian cancer cells express cancer antigen CA125. Further studies by Canney et al. found that 93% of ovarian cancer patients had elevated blood CA125 concentrations, while less than 1% of the healthy population had blood CA125 concentrations >65 U/ml. At present, serum CA125 has become one of the auxiliary diagnostic indicators of ovarian cancer, and it has a greater guiding role in determining the stage, progression, regression or recurrence of ovarian cancer. Further clinical studies found that not only the blood CA125 concentration increased in ovarian cancer patients, but also in other primary malignant tumors of gynecology, such as endometrial, fallopian tube, cervical and myometrial cancers, and some non-gynecological malignant tumors, such as lymphoma, breast cancer, melanoma, lung cancer, stomach cancer, liver cancer, bile duct cancer, pancreatic cancer, renal cell cancer and colorectal cancer. Some patients with non-gynecologic malignancies, such as lymphoma, breast cancer, melanoma, lung cancer, stomach cancer, liver cancer, bile duct cancer, pancreatic cancer, renal cell cancer and colorectal cancer, have elevated blood CA125 concentration, with a positive rate of about 22%. In addition, some patients with non-cancerous diseases, such as endometriosis, uterine fibrosis, pelvic inflammatory disease, pancreatitis, autoimmune diseases, pleurisy, pericardial infection, chronic renal failure and liver granulomatosis, may have moderately elevated CA125 concentrations (<270 U/ml), with a positive rate of 3% to 6%. Under certain normal physiological conditions, such as early pregnancy and menstruation, CA125 concentration may also increase, but not to a great extent. Thus, elevated blood CA125 concentration is not only seen in ovarian cancer patients, but also in other gynecological malignancies, non-gynecological tumors, chronic inflammation and certain physiological conditions. 2, CA125 concentration in serum or ascites of patients with tuberculous peritonitis In 1989, Ronay abroad reported 2 cases of elevated serum CA125 concentration in patients with tuberculous peritonitis, after which foreign scholars reported cases of elevated CA125 in patients with tuberculous peritonitis one after another, and in recent years, Chen Weizhong and others in China also found elevated serum CA125 concentration in patients with tuberculous peritonitis, therefore, tuberculous peritonitis Serum CA125 concentrations in patients can be higher than normal, and the possibility of tuberculous peritonitis should be considered when elevated serum CA125 concentrations are found. Mas et al. found that serum CA125 concentrations in patients with tuberculous peritonitis were more than 10 times normal before the application of antituberculous drugs, but returned to normal after 4 months of treatment; therefore, it is believed that serum CA125 concentrations can be used as an observational indicator of the efficacy of treatment for tuberculous peritonitis. There is not much research data on the concentration of CA125 in the ascites of tuberculous peritonitis. Some people reported that the concentration of CA125 in the ascites of patients with tuberculous peritonitis was elevated and higher than the serum CA125 level, and the detection of the level of CA125 in the ascites could help in the diagnosis of tuberculous peritonitis, but some people thought that the analysis of CA125 in the ascites did not help in the diagnosis, and the confirmation of the diagnosis also needed to rely on the dissection and pathological examination. 3, mechanism of elevated CA125 in serum or ascites of patients with tuberculous peritonitis Barbieri et al. applied CA125 monoclonal antibody to confirm by immunohistochemical study that CA125 is present in tissues of epithelial origin of normal embryonic body cavity, such as mesothelial tissues (including peritoneum, pleura and pericardium) and mullerian duct epithelium (including fallopian tubes, endometrium and endocervical lining), and when lesions occur in these tissues The specific mechanisms underlying the elevation of CA125 in serum or ascites of patients with tuberculous peritonitis are not well understood. Presumably, in tuberculous peritonitis, the mesothelial cells of the peritoneum are stimulated and the CA125 gene is activated, thus expressing and producing a large amount of CA125 that is released into the ascites and then absorbed into the circulation in a certain proportion through the peritoneal barrier, resulting in a significant increase in the level of CA125 in ascites and serum. 4, the significance of CA125 determination in the diagnosis and treatment of tuberculous peritonitis At present, the diagnosis of tuberculous peritonitis in clinical practice is mostly based on clinical symptoms, signs, ascites routine and other laboratory results, followed by experimental anti-tuberculosis treatment. It is more difficult to diagnose tuberculous peritonitis because patients often lack typical clinical manifestations and routine ascites examination often has no characteristic changes. Although peritoneal biopsy can provide a clear diagnosis, it is more difficult to obtain accurate biopsy tissue. Studies have found that the confirmation rate of caseous necrotizing granuloma is 47.6% and that characteristic changes such as peritoneal tuberculous nodules are not found in some patients with tuberculous peritonitis, the reason for which may be related to the small amount of biopsy tissue (routinely 2 to 3 pieces in general). Studies have shown that serum and/or ascites CA125 levels are elevated in patients with tuberculous peritonitis, and when unexplained abnormal serum and/or ascites CA125 levels are found to be elevated, tuberculous peritonitis should be highly suspected when abdominal or other organ disease is excluded. Serum CA125 concentrations can be significantly elevated in patients with ovarian cancer, and data suggest that serum CA125 concentrations can also be significantly elevated in patients with tuberculous peritonitis; therefore, in clinical workup, malignancy cannot be identified from tuberculous peritonitis based solely on the degree of elevated CA125 concentrations. In female patients, if there are tumors of uterine appendages, ascites, anemia, weight loss, and increased CA125 concentration, ovarian cancer must be considered first, but if only serum and ascites CA125 concentration is increased, tuberculous peritonitis should be considered as a possibility, and CA125 concentration in patients with tuberculous peritonitis can increase with the occurrence and development of tuberculous peritonitis and return to normal with the cure of the disease, therefore, dynamic Therefore, the dynamic observation and detection of CA125 concentration is of some significance for the diagnosis, treatment and follow-up of tuberculous peritonitis.