Barium Enema The white arrow indicated the rectosigmoid junction. Notice: (1) the irregular filling defect due to the large masses and the sharp end of the proximal colon; (2) the irregular shadow (white arrow head) in the lumen between the sigmoid colon and the rectum. It might be the prolapsed intestine which had not totally obscured the lumen as the large mass; (3) the sigmoid colon was shifted to the right abdomen.