Multiple small lymph nodes in the abdominal cavity and retroperitoneum may be caused by infectious diseases, intestinal tuberculosis diseases, malignant tumor diseases and other factors. 1. Infectious diseases: when the patient has inflammatory infectious diseases, such as peritonitis, intestinal inflammation, etc., it may induce the appearance of multiple small lymph nodes in the abdominal cavity and retroperitoneum. After anti-infective treatment for such diseases, most patients’ lymph nodes can gradually return to normal. 2. Intestinal tuberculosis disease: intestinal tuberculosis disease is generally due to the tuberculosis bacillus caused by chronic specific infectious diseases. When Mycobacterium tuberculosis invades the lymphocytes of the intestinal wall, it may cause multiple small lymph nodes, and the patients may also have abdominal pain, change of bowel habit and other symptoms. 3. Malignant neoplastic diseases: when malignant tumor cells start to spread, such as common intestinal malignant tumors, pelvic malignant tumors, etc., they will cause multiple small lymph nodes in the abdominal cavity. In addition, lymphoma, lymphocytic leukemia and other diseases may also cause multiple small lymph nodes in the abdominal cavity and retroperitoneum. There are many reasons to see multiple small lymph nodes in the abdominal cavity and retroperitoneum, so it is recommended to consult a doctor in time, based on the test results. Choose the appropriate treatment according to the doctor’s advice.