Ultrasound can look at the cervix. Ultrasound can see the size of the cervix and the presence of fibroids, cysts, abnormal lesions, etc. on the cervix. Yin ultrasound is usually more accurate than abdominal ultrasound and is adapted to patients who have sex. The probe is usually of higher resolution and clearer than abdominal ultrasound, especially for those who are obese and have ovaries in too deep a position and do not need to hold urine. Yin ultrasound is significantly better than abdominal ultrasound for the display of subtle lesions in the uterus, ovaries, fallopian tubes and pelvis, and is more sensitive to the display of blood flow signals. It is also more sensitive to the blood flow signal. It is more satisfactory to show the tiny masses and fluid in the pelvis, and is significantly better than abdominal ultrasound in diagnosing ectopic pregnancy. However, negative ultrasound usually cannot see whether there is inflammation of the cervix or precancerous lesions of the cervix, and polyps of the cervical opening are usually not easily shown under negative ultrasound.