In the clinic, I often have patients bring me ultrasound slips to see: “Doctor, is pelvic effusion pelvic inflammatory disease? The doctor at the other hospital said it was pelvic inflammatory disease and told me to hang a bottle of anti-inflammatory treatment for a week already, but I have no symptoms. What is the problem with pelvic effusion? Do I need to be treated? In the pelvic cavity, there is a depression between the back of the uterus and the rectum, which is medically called the utero-rectal sink. Ultrasound will measure the depth of the pelvic fluid and can determine the amount of fluid and the nature of the fluid may be water, blood or pus. The diagnosis of pelvic fluid is made by an ultrasound examination that describes a dark area of fluid. There are two types of pelvic effusion First of all, it is necessary to clarify whether it is physiological or pathological. 1. Physiological pelvic fluid Normally, there is 100 to 200 ml of plasma peritoneal fluid in the peritoneal cavity, more in women than in men. In addition, women may also have a small amount of pelvic fluid after ovulation or during menstruation, which can be seen by ultrasound examination as an arc-shaped or strip-shaped echogenic area in the rectal fossa of the uterus, which is more limited and has good sound transmission. Therefore, if no other problems are found, just a small amount of abdominal fluid found by ultrasonography is normal and will be absorbed on its own without treatment. 2, pathological pelvic fluid If the fluid is pathological, it shows poor sound transmission, relatively large amount of fluid, and a large range. Some pelvic diseases cause pelvic effusion in women, and ultrasound examination should pay attention to the presence or absence of light point echo, dark area sound transmission, and the amount of effusion. Because ultrasound is non-invasive and painless, the accuracy rate is high, and it has a high reference value for clinical diagnosis. Common diseases include: pelvic inflammatory disease, pelvic abscess, ovarian chocolate cyst, ruptured corpus luteum, ruptured ectopic pregnancy, tuberculosis, and even malignant tumor. Of course, the specific diagnosis should be combined with the patient’s symptoms, signs and other examination tests to give a comprehensive judgment. It can be seen that pelvic effusion can be both physiological and pathological. In determining the nature of effusion, a comprehensive analysis and judgment should be made. If there is no symptom, but ultrasound indicates pelvic effusion with a depth of about 1 to 3 cm, no treatment is needed. However, if it is accompanied by abdominal pain, fever, irregular menstruation, dysmenorrhea, abnormal leucorrhea, gastrointestinal tract and other symptoms, it is recommended to go to the hospital for examination to avoid delaying treatment.