It is normal that there will be no dark areas of fluid and no dark areas of fluid of several centimeters during the pelvic ultrasound examination of the uterus. For example, when there is a dark area of fluid in the pelvic cavity, it indicates physiological fluid caused by follicle rupture, which usually subsides after the end of menstruation and will not affect health. However, when the ultrasound is repeated 2-3 days after the end of menstruation, it indicates that there will be a dark area of fluid and pelvic inflammatory disease. The presence of fluid dark areas in the uterine cavity indicates fluid dark areas due to endometrial inflammation, incomplete endometrial exfoliation or poor contraction of the uterus after medication or abortion, which should be treated with medication to activate blood circulation and remove blood stasis, otherwise it will affect the contraction of the uterus and will have adverse effects on future pregnancy.