Rectal duplication is a rare congenital anorectal malformation characterized by an egg-like, cystic, mucus-filled mass, composed of intestinal mucosal lining and smooth muscle tissue. Commonly they present in childhood with symptoms of recurrent urinary tract infections, gastroenteritis, obstruction, perianal sepsis and rectal bleeding. Drainage of mucus or pus from the anus is also a typical presenting sign. The majority are found in the retro-rectal space where they communicate with, or are contiguous to, the rectum. The disease is Monarch Disease Ontology identifier MONDO_0015734 (rectal duplication).