Pelvic fluid can cause pain and swelling in the lower abdomen. Pelvic fluid usually means inflammation in the pelvic cavity, which is why there is exudation and fluid accumulation, and the fluid accumulation will stimulate the pelvic floor muscles, which will become tense after being stimulated by the inflammation. If pelvic fluid is present for a long time, it will cause the muscles to contract for a long time, and after the muscles contract for a long time, they will shorten, and during the shortening process, painful trigger points will appear inside the muscles, resulting in a painful sensation in the pelvic floor. The pelvic floor muscles are actually part of the entire core muscle group, which includes the transversus abdominis, multifidus and diaphragm muscles. If the pelvic floor muscles become dysfunctional, this can lead to problems with other muscles, such as the development of small abdominal pain. Some patients also experience lumbosacral pain or thigh pain, so pelvic fluid can cause pain in the lower abdomen. Anti-infection treatment is needed first for such patients, but sometimes the above treatment is not enough and the muscles need to be treated along with the inflammation in order to achieve effective treatment.