Rectal disorders Artwork of a section through the rectum Rectal polyps centre left red and lower centre pink are small benign growths on the rectal lining They could potentially become a rectal carcinoma pink and therefore should be removed Internal and external haemorrhoids blue are blood vessels that have become dilated and swollen due to high internal pressure An anal fistula below internal haemorrhoid is a split in the rectum that forms into a channel that opens in the skin It is caused by infection and inflammation An abscess lower right is a pocket of pus formed due to a bacterial infection