An endometrial lining of more than 11 millimeters after 5 days of menstruation is normal, but if it is accompanied by symptoms such as abnormal bleeding or abdominal pain and discomfort, you need to seek medical attention to rule out the abnormality. The thickness of the endometrium usually fluctuates within a range and is affected by factors such as the menstrual cycle as well as the onset of menstruation. Since a woman’s menstrual cycle usually lasts 5 to 7 days, and the fifth day is in the second half of the menstrual cycle, the overall trend of endometrial lining thickness shows a gradual thickening from the first half of the menstrual cycle to the second half of the menstrual cycle. At this time, if not accompanied by obvious discomfort symptoms, the endometrium reaches 11 millimeters is mostly normal. If the endometrium reaches 11 mm a few days after the end of menstruation, which suggests uneven echogenicity or is accompanied by abnormal abdominal pain or vaginal bleeding, it may indicate the presence of endometrial polyps or abnormal endometrial hyperplasia, which need to be taken seriously, and the patient should go to the hospital for a detailed checkup in a timely manner, and treatment should be carried out according to the results and the doctor’s instructions.