[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Gastrointestinal tract](https://durgical.com/en/general-pathology/areas/gi/) › Sigmoid diverticular disease

# Sigmoid diverticular disease

- Lesion

High pressure inside the colon pushes its lining out through weak spots in the muscle, forming small pouches that can inflame or bleed.

Updated Nov 12, 2026

## Key points

- False diverticula: mucosa and submucosa only, covered by thin subserosal fat.
- Sigmoid most often in Western populations; right colon more often in Asian and African populations.
- Small flask-like pouches, regularly spaced along the vasa recta entry points.
- Hypertrophy of the inner circular muscle is common.
- Diverticulitis: inflammation, often from obstruction of the neck; can perforate, form pericolic abscesses, sinus tracts, fistulas and peritonitis.
- A classic cause of painless brisk lower GI bleeding in older adults.

## What it is

Colonic diverticula are acquired outpouchings of mucosa and submucosa through the muscularis propria, so they are false diverticula. They form at points where nerves and vasa recta pierce the inner circular muscle, which in the colon is not reinforced by a complete outer longitudinal coat because that layer is gathered into the three taeniae coli. Exaggerated sigmoid contractions with low-fibre diets raise the pressure. Prevalence approaches half of Western adults over sixty.

## Structure

- Gross: rows of small outpouchings along the sigmoid between the taeniae; thick muscular wall.
- Micro: diverticular wall of mucosa with muscularis mucosae, separated from serosa by fat; attenuated or absent muscularis propria.
- Diverticulitis: inflammation in the pouch and surrounding fat, sometimes abscess or fistula.

## Step by step

- Low-fibre diet leads to small hard stools and strong segmental contractions.
- Intraluminal pressure rises, especially in the sigmoid.
- Mucosa herniates through gaps where vasa recta and nerves cross the inner muscle.
- Stool or debris blocks the diverticular neck; bacteria proliferate.
- Inflammation of the thin wall leads to perforation, abscess or peritonitis.

## Clinical notes

- Most people with diverticulosis never have symptoms; about one in five has cramping, discomfort or altered bowel habit.
- Diverticulitis presents with left lower quadrant pain and fever, the so-called left-sided appendicitis.

## Memory aid

Pressure pushes the lining through the gaps where the vessels enter: a pseudo-pouch with no muscle to protect it.

## Test yourself

Think of the answer, then tap the question to see it.

## Why are colonic diverticula called false diverticula?

They contain only mucosa and submucosa, which herniate through the muscularis propria.

## Why does the colon form diverticula more readily than the small bowel?

Its outer longitudinal muscle is gathered into taeniae, leaving the sites where vessels pierce the inner circular layer unreinforced.

## What are the complications of diverticulitis?

Perforation, pericolic abscess, sinus tracts, fistulas and peritonitis; diverticula can also bleed.

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## Elsewhere in DurgiPedia

- [Small bowel and colon motility](https://durgical.com/en/physiology/small-bowel-and-colon-motility/)

## Connections

## Related 4

- [Meckel diverticulum, and true vs false diverticula](https://durgical.com/en/general-pathology/meckel-diverticulum-and-true-vs-false-diverticula/)
- [Angiodysplasia](https://durgical.com/en/general-pathology/angiodysplasia/)
- [Diseases of the peritoneum](https://durgical.com/en/general-pathology/diseases-of-the-peritoneum/)
- [Patterns of acute inflammation: serous, fibrinous, purulent, abscess, ulcer](https://durgical.com/en/general-pathology/patterns-of-acute-inflammation-serous-fibrinous-purulent-abscess-ulcer/)

## Related conditions 6

- [Diverticular disease and diverticulitis](https://durgical.com/en/conditions/diverticular-disease-and-diverticulitis/)
- [Lower gastrointestinal bleeding](https://durgical.com/en/conditions/lower-gastrointestinal-bleeding/)
- [Intra-abdominal abscess](https://durgical.com/en/conditions/intra-abdominal-abscess/)
- [Peritonitis](https://durgical.com/en/conditions/peritonitis/)
- [Large bowel obstruction](https://durgical.com/en/conditions/large-bowel-obstruction/)
- [Constipation and faecal impaction](https://durgical.com/en/conditions/constipation-and-faecal-impaction/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Diverticular Disease of the Colon](https://www.ncbi.nlm.nih.gov/books/NBK541110/) (StatPearls (NCBI Bookshelf), 2025).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/sigmoid-diverticular-disease/