12-year-old girl with constipation and rectal bleeding

Rectal duplication cysts are rare, thought to be due to defects in embryologic development, and often associated with other structural abnormalities. Clues to the existence of a rectal cyst are mainly due to bowel compression and presence of ectopic gastric mucosa within the cyst, leading to rectal bleeding. The diagnosis of a rectal duplication cyst requires a high index of suspicion. Confirming the diagnosis can be difficult based on the location of the cyst. Efforts to confirm the diagnosis include digital rectal examination, computed tomography, magnetic resonance imaging, ultrasonography, and Meckel scan. Surgical resection is the treatment of choice, especially because of the cyst's potential for malignant transformation. Because of the cyst's proximal location to the nerves innervating the anal canal and sphincters, surgical resection can lead to fecal incontinence.