There are various reasons for seeing a small cystic mass in the uterine cavity. The small cystic mass may be a gestational sac, uterine fibroid liquefaction, uterine cyst, etc. The specific analysis is as follows. 1. gestational sac: the gestational sac is the initial form of the fetus in the uterus, disappears after 11 weeks of pregnancy, the presence of the gestational sac in the uterine cavity means that the pregnancy is already pregnant, but further ultrasound, blood HCG and other tests to rule out ectopic pregnancy and other conditions. 2. Liquefaction of uterine fibroids: it is a common cause of cystic mass in the uterine cavity, after liquefaction of uterine fibroids, cystic mass can be formed in the uterine cavity. Most of the cystic masses can disappear after surgical removal of fibroids. 3. Uterine cysts: rare, mostly cervical cysts. They should be treated with drugs or surgical excision under the guidance of doctors. Small cystic masses in the uterine cavity should pay attention to rest, do not exercise strenuously, avoid staying up late, go to the hospital in time to clarify the cause of the disease, symptomatic treatment.