In general, ultrasound is difficult to clearly show the structure of normal fallopian tubes, and only when morphological changes in the uterine adnexal structures occur, there are changes in the ultrasound sonography. Therefore, early mild tubal blockage often does not have any ultrasound manifestation. Only when the blockage causes changes in the morphology and volume of the fallopian tubes or if there is a large amount of fluid in the pelvis, the structures of the fallopian tubes can be seen on ultrasound. When morphologic changes occur in the fallopian tubes, ultrasound can visualize the uterus and adnexa not only transabdominally, but also more clearly using transvaginal ultrasound. The fallopian tube is a curved tube-like structure connected to the uterine horn with the ovaries and ligaments below. However, in clinical cases such as tubal infection or tubal effusion, the structure of the fallopian tubes can be clearly shown on ultrasound due to congestion, swelling, thickening, bending and fluid accumulation. In addition, transvaginal ultrasound can also clearly show the blood flow signal on the wall of the fallopian tube, which can be used to determine the disease of the fallopian tube. Therefore, it is usually difficult to detect tubal blockage on ultrasound, but only when tubal blockage leads to thickening, swelling and fluid accumulation can be detected on ultrasound.