[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/) › Intestinal obstruction # Intestinal obstruction - Lesion The bowel can be blocked by being trapped in a hernia, tied by scar bands, twisted on itself or telescoped into the next segment. Updated Nov 12, 2026 ## Key points - Hernias: the leading cause worldwide; inguinal hernias with narrow necks and large sacs are the classic culprits. - Incarceration (permanently trapped) leads to strangulation (blood supply cut) and infarction. - Adhesions after surgery, infection or endometriosis create internal hernias; the leading cause in countries with much abdominal surgery. - Volvulus: twist around the mesentery; sigmoid most often, then caecum, small bowel and stomach. - Intussusception: the commonest cause of obstruction under age two, usually idiopathic (lymphoid hyperplasia, viral infection); in adults a tumour is the lead point. - Features: colicky pain, distension, vomiting, constipation. ## What it is Obstruction can occur at any level but most often in the small intestine, whose lumen is narrow. Four mechanical causes account for about four in five cases: hernias, adhesions, volvulus and intussusception; tumours, infarcts and strictures (for example Crohn disease) make up the rest. The danger is not only the blocked lumen but the blood supply: trapped or twisted bowel loses venous drainage first, then arterial inflow, and infarcts. ## Structure - Strangulated loop: dusky, purple, haemorrhagic serosa with a sharp edge at the neck of the trap. - The telescoped segment (intussusceptum) drags its mesentery into the receiving segment (intussuscipiens). ## Step by step - A segment of bowel is trapped, kinked, twisted or telescoped. - Thin-walled veins are compressed first: congestion and oedema. - Swelling traps the loop further (incarceration). - Arterial inflow is cut: strangulation. - Haemorrhagic infarction, then perforation and peritonitis. ## The four mechanical causes | Cause | Mechanism | Who | Clue | | --- | --- | --- | --- | | [Hernia](https://durgical.com/en/conditions/inguinal-hernia/) | Bowel in a peritoneal sac through a wall defect | Any age | Groin or umbilical swelling | | [Adhesions](https://durgical.com/en/conditions/small-bowel-obstruction/) | Fibrous bands form loops that trap bowel | After surgery or peritonitis | Previous laparotomy | | [Volvulus](https://durgical.com/en/conditions/sigmoid-volvulus/) | Twist around the mesenteric attachment | Older adults (sigmoid); infants with malrotation (midgut) | Coffee-bean loop on imaging | | [Intussusception](https://durgical.com/en/conditions/intussusception/) | A segment telescopes into the next one | Infants; adults with a tumour lead point | Currant-jelly stool, sausage mass | ## Clinical notes - Air or contrast enemas can both diagnose and reduce idiopathic intussusception in young children. - In cystic fibrosis, sticky stool can act as the lead point of intussusception. ## Memory aid Trapped, tied, twisted, telescoped: the four Ts of mechanical obstruction. ## Test yourself Think of the answer, then tap the question to see it. ## What are the four main mechanical causes of intestinal obstruction? Hernias, adhesions, volvulus and intussusception. ## Why does a strangulated hernia infarct? Pressure at the neck first blocks venous drainage, the loop swells, and arterial supply is then cut off. ## What usually serves as the lead point of intussusception in adults? An intraluminal mass or tumour. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/intestinal-obstruction/) [More Pathology questions →](https://durgical.com/en/practice/?f=pathology) ## Elsewhere in DurgiPedia - [Bowel obstruction syndrome](https://durgical.com/en/clinical-exam/bowel-obstruction-syndrome/) ## Connections ## Related 5 - [Ischaemic bowel disease](https://durgical.com/en/general-pathology/ischaemic-bowel-disease/) - [Meckel diverticulum, and true vs false diverticula](https://durgical.com/en/general-pathology/meckel-diverticulum-and-true-vs-false-diverticula/) - [Non-neoplastic colonic polyps](https://durgical.com/en/general-pathology/non-neoplastic-colonic-polyps/) - [Crohn disease](https://durgical.com/en/general-pathology/crohn-disease/) - [Infarction: red vs white, and what decides the damage](https://durgical.com/en/general-pathology/infarction-red-vs-white-and-what-decides-the-damage/) ## Related conditions 11 - [Small bowel obstruction](https://durgical.com/en/conditions/small-bowel-obstruction/) - [Large bowel obstruction](https://durgical.com/en/conditions/large-bowel-obstruction/) - [Inguinal hernia](https://durgical.com/en/conditions/inguinal-hernia/) - [Femoral hernia](https://durgical.com/en/conditions/femoral-hernia/) - [Sigmoid volvulus](https://durgical.com/en/conditions/sigmoid-volvulus/) - [Intestinal malrotation with midgut volvulus](https://durgical.com/en/conditions/intestinal-malrotation-with-midgut-volvulus/) - [Intussusception (children)](https://durgical.com/en/conditions/intussusception/) - [Umbilical hernia](https://durgical.com/en/conditions/umbilical-hernia/) - [Incisional (ventral) hernia](https://durgical.com/en/conditions/incisional-hernia/) - [Cystic fibrosis](https://durgical.com/en/conditions/cystic-fibrosis/) - [Postoperative ileus](https://durgical.com/en/conditions/postoperative-ileus/) [← All of general pathology](https://durgical.com/en/general-pathology/) 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: [Small Bowel Obstruction](https://www.ncbi.nlm.nih.gov/books/NBK448079/) (StatPearls (NCBI Bookshelf), 2025); [Sigmoid Volvulus](https://www.ncbi.nlm.nih.gov/books/NBK441925/) (StatPearls (NCBI Bookshelf), 2025); [Child Intussusception](https://www.ncbi.nlm.nih.gov/books/NBK431078/) (StatPearls (NCBI Bookshelf), 2025). ## **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/general-pathology/intestinal-obstruction/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/intestinal-obstruction/