An uncommon congenital abnormality. Patients usually present with constipation but acute obstruction is less commonly reported.

The pathogenesis remains unknown and hypotheses have been proposed:

Colonic and rectal duplication may be cystic or tubular, the latter more common in the rectum. It is usually segmental and can be classified into the various types:

Type 1 Segmental colonic duplication without other caudal duplication

Type 2 Complete or segmental colonic duplication with genitourinary duplication

Patient Case Example of Type IIa Colonic Duplication.

Fig a. Selected post contrast axial CT image slice demonstrating a duplicated anorectal junction and cervix.
Fig b. Selected post contrast coronal CT image illustrating a duplicated rectum
Fig c. Selected post contrast axial CT image confirming duplicated sigmoid colon and uterus
Fig d. Selected post contrast axial CT image demonstrating a duplicated descending colon
Fig e. Selected post contrast coronal CT image of a duplicated splenic flexure
Fig f. Selected post contrast coronal CT image of a duplicated caecum

References:

1. Congenital anomalies of the small intestine, colon, and rectum. Berrocal T, Lamas M, Gutieérrez J, Torres I, Prieto C, del Hoyo ML. Radiographics. 1999 Sep- Oct;19(5):1219-36.
2. Duplication of the colon: varied presentations of a rare congenital anomaly. Carr SL, Shaffer HA Jr, de Lange EE. Can Assoc Radiol J. 1988 Mar;39(1):29-32.