[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) › Sigmoid colon [Digestive system](https://durgical.com/en/anatomy/system/digestive-system/) · [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) # Sigmoid colon The sigmoid colon is the S-shaped last part of the colon, in the lower left belly, joining the rectum; it is a common site of diverticula and twisting. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=abdomen&select=sigmoid_colon&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The S-shaped last part of the colon, in the lower left [abdomen](https://durgical.com/en/anatomy/region/abdomen/), joining the rectum. ## What it does Stores stool before it passes to the rectum. ## Key points - Sigmoid volvulus: a long, redundant loop on a narrow mesocolic root twists; seen in older, bedridden or chronically constipated people and in Chagas megacolon - Commonest site of colonic diverticula in Western populations: the mucosa herniates where vasa recta pierce the circular muscle, between the taeniae - Chagas disease (Trypanosoma cruzi), present in Colombia, destroys the myenteric plexus and can cause megacolon, mostly of the sigmoid and rectum ## Key facts **Where** From pelvic brim to rectosigmoid junction at S3; intraperitoneal on sigmoid mesocolon; S-shaped and mobile **Blood supply** Sigmoid arteries (IMA, usually 2–4) **Nerve** Inferior mesenteric plexus (sympathetic, L1–L2); pelvic [splanchnic nerves](https://durgical.com/en/anatomy/greater-thoracic-splanchnic-nerve/) (S2–S4) **Function** Stores stool before the rectum; common site of diverticula and volvulus ## Relations **Course** From the pelvic brim it forms an S-shaped loop into the [pelvis](https://durgical.com/en/anatomy/region/pelvis/) and back to the midline, joining the [rectum](https://durgical.com/en/anatomy/rectum/) where the taeniae spread out and the [mesocolon](https://durgical.com/en/anatomy/mesocolon/) ends **In front** Loops of [ileum](https://durgical.com/en/anatomy/ileum/) and the anterior abdominal wall of the left iliac fossa **Behind** At the apex of its mesocolon: the left [ureter](https://durgical.com/en/anatomy/ureter/), the left common iliac vessels and the gonadal vessels; in the pelvis, the [piriformis](https://durgical.com/en/anatomy/piriformis-muscle/) and the sacral plexus **Below** Bladder, and in women the uterus and [ovaries](https://durgical.com/en/anatomy/ovary/); coils sit in the rectovesical or [rectouterine pouch](https://durgical.com/en/anatomy/rectouterine-pouch/) ## How to find it It lies in the left iliac fossa and pelvis; in thin people a stool-filled sigmoid is sometimes felt there as a firm cord. Flexible sigmoidoscopy examines it from the anus, for screening and for decompressing a volvulus. ## On imaging Sigmoid volvulus on an abdominal X-ray: the coffee-bean sign, a large inverted-U loop of gas rising from the pelvis toward the upper abdomen; a contrast enema shows a bird-beak taper at the twist. CT is the main test for diverticulitis: fat stranding, wall thickening, abscess or free gas. ## Common problems - Diverticulitis: inflamed pouches; left lower pain and fever. - Sigmoid volvulus (a twist). ## How it is diagnosed Colonoscopy; CT; stool tests for screening. ## Treatment - Polyps removed during colonoscopy; surgery (colectomy) for cancer or complicated disease. ## Clinical notes - Endoscopic decompression often untwists a volvulus without gangrene; it tends to recur, so a later resection is often planned - Diverticulitis can form a pericolic abscess or a colovesical fistula (gas or stool in the urine) - Hartmann procedure: sigmoid resection with an end colostomy and a closed rectal stump, used for perforated diverticulitis or obstruction - Pain from the sigmoid (hindgut) begins suprapubically and moves to the left iliac fossa when the [peritoneum](https://durgical.com/en/anatomy/peritoneum/) is inflamed, a «left-sided appendicitis» picture ## Anatomical variants - Length and redundancy vary (about 25–40 cm); a long loop with a narrow root predisposes to volvulus ## Development A hindgut derivative that, unlike the [descending colon](https://durgical.com/en/anatomy/descending-colon/), keeps its mesentery. In Hirschsprung disease neural crest cells fail to reach the end of the bowel, so the rectum and often the sigmoid lack ganglion cells: the newborn passes meconium late and the bowel above the narrow segment distends. ## Related conditions - [Colorectal cancer](https://durgical.com/en/conditions/colorectal-cancer/) - [Diverticular disease and diverticulitis](https://durgical.com/en/conditions/diverticular-disease-and-diverticulitis/) - [Sigmoid volvulus](https://durgical.com/en/conditions/sigmoid-volvulus/) - [Large bowel obstruction](https://durgical.com/en/conditions/large-bowel-obstruction/) - [Ulcerative colitis](https://durgical.com/en/conditions/ulcerative-colitis/) - [Irritable bowel syndrome](https://durgical.com/en/conditions/irritable-bowel-syndrome/) - [Chagas disease](https://durgical.com/en/conditions/chagas-disease/) - [Lower gastrointestinal bleeding](https://durgical.com/en/conditions/lower-gastrointestinal-bleeding/) - [Clostridioides difficile infection](https://durgical.com/en/conditions/clostridioides-difficile-infection/) - [Colorectal polyps and hereditary polyposis syndromes (FAP, Lynch)](https://durgical.com/en/conditions/colorectal-polyps-and-hereditary-polyposis-syndromes/) - [Ischaemic colitis](https://durgical.com/en/conditions/ischaemic-colitis/) - [Constipation and faecal impaction](https://durgical.com/en/conditions/constipation-and-faecal-impaction/) - [Chagasic megaoesophagus and megacolon](https://durgical.com/en/conditions/chagasic-megaoesophagus-and-megacolon/) - [Bacterial infectious diarrhoea and dysentery](https://durgical.com/en/conditions/bacterial-infectious-diarrhoea-and-dysentery/) - [Hirschsprung disease](https://durgical.com/en/conditions/hirschsprung-disease/) - [Functional constipation in children](https://durgical.com/en/conditions/functional-constipation-in-children/) ## Test yourself Think of the answer, then tap the question to see it. ## What predisposes the sigmoid colon to volvulus? A long, redundant loop on a narrow mesocolic root; it occurs in older, bedridden or constipated people and in Chagas megacolon. ## What does sigmoid volvulus show on a plain abdominal X-ray? The coffee-bean sign: a large inverted-U loop of gas rising from the pelvis; a contrast enema shows a bird-beak taper. ## Why do diverticula form in the sigmoid colon? The mucosa herniates where vasa recta pierce the circular muscle, between the taeniae; the sigmoid is the commonest site in Western populations. ## What is a Hartmann procedure? Sigmoid resection with an end colostomy and a closed rectal stump, used for perforated diverticulitis or obstruction. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/sigmoid-colon/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** colon sigmoideum TA2 2987 **Official Spanish (DeCS)** Colon sigmoide DeCS D012809 **English (TA2)** Sigmoid colon **Also called** colon sigmoides ## Related - [Descending colon](https://durgical.com/en/anatomy/descending-colon/) - [Ureters](https://durgical.com/en/anatomy/ureter/) - [Inferior mesenteric artery](https://durgical.com/en/anatomy/inferior-mesenteric-artery/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=13194); [Anatomy, Abdomen and Pelvis, Sigmoid Colon](https://www.ncbi.nlm.nih.gov/books/NBK549824/); [23.5 The Small and Large Intestines](https://openstax.org/books/anatomy-and-physiology-2e/pages/23-5-the-small-and-large-intestines) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/sigmoid-colon/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/sigmoid-colon/