Anat Cell Biol.  2013 Dec;46(4):299-302. 10.5115/acb.2013.46.4.299.

Right sided descending and sigmoid colon: its embryological basis and clinical implications

• Shrivastava P
• Tuli A
• Kaur S
• Raheja S

• KMID: 2046772
• DOI: http://doi.org/10.5115/acb.2013.46.4.299

Abstract

Anatomical variations of the colon are described by various authors, but the occurrence of right sided descending and sigmoid colon is rare and has not been reported. We found that the anomalous right-sided descending and sigmoid colon had four parts. The proximal segment of the first part consisted of the descending colon extending across the midline from the splenic flexure to the portion supplied by the left colic artery. The distal segment was supplied by the superior sigmoid artery. The second and third parts formed a loop in the right lumbar region anterior to the lumbar cecum. The fourth part was in the lesser pelvis, extending from right sacroiliac joint to the third sacral body. Parts two, three, and four were supplied by the inferior sigmoid artery, which arose from the right side of the inferior mesenteric artery. The ascending and transverse colon was normally placed. This is a rare anomaly that has not been reported so far in adults and is of immense importance to interventional radiologists and colorectal surgeons. The embryological basis of such an anomaly is defective fixation occurring as early as the 12th-17th week of intrauterine life.

Keyword

Descending colon; Sigmoid colon; Morphology; Blood supply; Development

MeSH Terms

Adult
Arteries
Cecum
Colic
Colon
Colon, Descending
Colon, Sigmoid*
Colon, Transverse
Humans
Lesser Pelvis
Lumbosacral Region
Mesenteric Artery, Inferior
Sacroiliac Joint

Figure

• 

  Fig. 1 Anterior view of anomalous colon in situ after removing jejunum and ileum. 1, part 1 of anomalous colon; 2, part 2 of anomalous colon; 3, part 3 of anomalous colon; 4, part 4 of anomalous colon; S, superior; I, inferior; L, left; R, right; a, hepatic flexure; b, ascending colon; c, sigmoid loop anterior to caecum; d, right iliopsoas muscle; e, transverse mesocolon; f, transverse colon; g, superior mesenteric vessels; h, abdominal aorta; i, cut end of ileo-cecal junction.

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  Fig. 2 Photograph showing the location of the right-sided sigmoid loop. a, ileum; b, sigmoid loop; c, jejunum; d, duodeno-jejunal junction; e, splenic flexure; f, common mesentery.

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  Fig. 3 Fig showing complete large intestine after removal of small intestine. The sigmoid loop has been displaced downwards and to the left showing its posterior aspect. S, superior; I, inferior; L, left; R, right; a, transverse mesocolon; b, transverse colon; c, ascending colon; d, aorta; e, ileo-caecal junction; f, sigmoid loop turned downwards & to left; g, caecum.

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  Fig. 4 Photograph showing the vascular supply of the right-sided sigmoid loop. a, sigmoid loop; b, inferior sigmoid artery; c, superior rectal artery; d, inferior mensenteric artery; e, left colic artery; f, superior sigmoid artery; g, bifurcation of aorta.

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  Fig. 5 Photograph showing the branches of inferior mesenteric artery lying posterior to the sigmoid loop which is turned downwards and to the left to expose the artery. S, superior; I, inferior; L, left; R, right; a, left colic artery; b, transverse mesocolon; c, transverse colon; d, aorta; e, hepatic flexure; f, sigmoid loop turned downwards and to the left; g, left sigmoid artery; h, right sigmoid artery; i, inferior mesenteric artery; j, ileo-colic junction.

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