aetiology of intestinal obstruction

AETIOLOGY

CAUSES OF INTESTINAL OBSTRUCTION

Dynamic Intraluminal impaction foreign bodies bezoars gallstones Intramural stricture malignancy

Extramural bands/adhesions hernia Volvulus Intussusception

Adynamic Paralytic ileus Mesenteric vascular

occlusion Pseudo -obstruct

Common causes of obstruction

ADHESION

TUMOR HERNIA

Internal herniaA portion of the SI becomes entrapped in one of the retroperitoneal fossae or in a congenital mesenteric defect

Sites Foramen of Winslow Holes in the mesentery or transverse

mesocolon Defect in the broad ligament Diaphragmatic hernia Duodenal/caecal/appendiceal

retroperitoneal fossae

Obstruction from enteric stricture

Secondary to tuberculosis or crohn’s diseaseTreatment- Resection & anastomosis

Bolus Obstruction

1. Gall stones In the elderly 20 to erosion of a large gallstone through the gallbladder into the duodenum Classically there is impaction about 60 cm proximal to the ileocaecal valve

2. Food Occur after partial or total gastrectomy when

unchewed articles can pass into the small bowel

3. StercolithIn association with jejunal diverticulum or ileal stricture

4. TrichobezoarFirm masses of undigested hair ballsAssociated with an underlying psychiatric abnormality

5. PhytobezoarFirm masses of fruit or vegetable fibres

Predisposing factors High fibre intake Inadequate chewing Previous gastric surgery Hypochlorhydria Loss of the gastric pump mechanism

6. WormsAscaris LumbricoidesIn childrenAn attack frequently follows the initiation of antihelminthic therapy

ADHESIONCommon cause of intestinal obstruction in western countriesAny peritoneal irritation → local fibrin production → adhesions between opposed surfacesCauses Ischemic areas- Sites of anastomoses, trauma

vascular occlusion Foreign material- Talc , starch, gauze, silk Infection- Peritonitis, tuberculosis Inflammatory conditions- Crohn’s disease Radiation enteritis

INTUSSUSCEPTION

One portion of the gut becomes invaginated within an immediately adjacent segmentCommonly in children(5-10 months)90% idiopathicSecondary to intestinal pathology. Eg. Polyp, Meckels diverticulumHyperplasia of the Peyer’s patch in the terminal ileum may be the initiating event

Volvulus

Twisting or axial rotation of a portion of bowel about its mesenteryPrimary or secondary10 – occurs secondary to congenital malrotation of the gut, abnormal mesenteric attachments, congenital bands20 – rotation of a piece of bowel around an acquired adhesion or stoma