INTESTINAL OBSTRUCTION

CLASSIFICATION

• Dynamic- acute or a chronic form

• Adynamic

CAUSES OF INTESTINAL OBSTRUCTION

• Intraluminal

• Impaction

• Foreign bodies

• Bezoars

• Gallstones

• Intramural

• Stricture

• Malignancy

• Extramural

• Bands/adhesions

• Hernia

• Volvulus

• Intussusception

• Paralytic ileus

• Mesenteric vascular occlusion

• Pseudo-obstruction

PATHOPHYSIOLOGY

• proximal bowel dilates

• altered motility

• Below the obstruction normal peristalsis and absorption

• Initially, proximal peristalsis is increased

• not relieved, the bowel begins to dilate

• flaccidity and paralysis

• prevent vascular damage

• overgrowth of both aerobic and anaerobic organisms

• gas production

• nitrogen (90%) and hydrogen sulphide

• various digestive juices

• fluid accumulates within the bowel wall secreted

• absorption from the gut is retarded

• Dehydration and electrolyte loss

• reduced oral intake

• defective intestinal absorption

• Vomiting

• sequestration in the bowel lumen

STRANGULATION

• venous return is compromised before the arterial supply

• increase in capillary pressure

• local mural distension

• loss of intravascular fluid and red blood cells intramurally and extraluminally

• Once the arterial supply is impaired

• haemorrhagic infarction

• marked translocation and systemic exposure to anaerobic organisms with their associated toxins

• morbidity of intraperitoneal strangulation is far greater than with an external hernia

CAUSES OF STRANGULATION

• Hernial

• Adhesions/bands

• Interrupted blood flow

• Volvulus

• Intussusception

• Mesenteric infarction

CLINICAL FEATURES OF INTESTINALOBSTRUCTION

• Dynamic obstruction

• classic quartet of pain, distension, vomiting and absolute constipation

FEATURES OF OBSTRUCTION

• high small bowel obstruction

• vomiting occurs early and is profuse

• rapid dehydration

• Distension is minimal

• little evidence of fluid levels on abdominal radiography

• low small bowel obstruction

• pain is predominant with central distension

• Vomiting is delayed

• Multiple central fluid levels are seen on radiography

• In large bowel obstruction

• distension is early and pronounced

• Pain is mild

• vomiting and dehydration are late

• The proximal colon and caecum are distended on abdominal radiography

CLINICAL FEATURES OF STRANGULATION

• Constant pain

• Tenderness with rigidity

• Shock

CLOSED-LOOP OBSTRUCTION

• obstructed at both the proximal and distal points

• no early distension of the proximal intestine

• gangrene

• retrograde thrombosis of the mesenteric veins

• malignant stricture of the right colon with a competent ileocaecal valve

• Unrelieved, this results in necrosis and perforation

INTERNAL HERNIA

• a portion of the small intestine becomes entrapped in one of the retroperitoneal fossae or in a congenital mesenteric defect

• the foramen of Winslow

• a hole in the mesentery

• transverse mesocolon

• broad ligament

• congenital or acquired diaphragmatic hernia

• duodenal retroperitoneal fossae – left paraduodenal and right duodenojejunal

• caecal/appendiceal retroperitoneal fossae – superior, inferior and retrocaecal intersigmoid fossa

ENTERIC STRICTURES

• tuberculosis

• Crohn’s disease

• Lymphoma

• carcinoma and sarcoma are rare

• subacute or chronic

BOLUS OBSTRUCTION

• food

• gallstones

• trichobezoar, phytobezoar

• stercoliths

• worms

GALLSTONES

• erosion of a large gallstone through the gall bladder into the duodenum

• 60 cm proximal to the ileocaecal valve

• recurrent attacks

• air–fluid level in the biliary tree

• The stone may not be visible

FOOD

• partial or total gastrectomy

• Fruit and vegetables

TRYCHOBEZOARS AND PHYTOBEZOARS

• firm masses of hair balls and fruit/vegetable fibre

• Psychiatric abnormality

• high fibre intake, inadequate chewing, previous gastric surgery

• hypochlorhydria and loss of the gastric pump mechanism

STERCOLITHS

• jejunal diverticulum or ileal stricture

• identical to that of gallstones

WORMS

• Ascaris lumbricoides

• children, the institutionalised and those near the tropics

• attack frequently follows the initiation of anti-helminthic therapy

• Debility is frequently out of proportion to that produced by the obstruction.

• eosinophilia or the sight of worms within gas-filled small bowel loops

OBSTRUCTION BY ADHESIONS AND BANDS

• Adhesions

• most common cause

• in the early postoperative period difficult to differentiate from paralytic ileus

• peritoneal irritation results in local fibrin production

• Early fibrinous adhesions may disappear

CAUSES OF INTRA-ABDOMINAL ADHESIONS

• Sites of anastomoses reperitonealisation of raw areas trauma vascular occlusion

• Talc, starch, gauze, silk

• Peritonitis, tuberculosis

• Crohn’s disease

• Radiation enteritis

• Bands

• obliterated vitellointestinal duct

• a string band following previous bacterial peritonitis

• a portion of greater omentum, usually adherent to the parietes

ACUTE INTUSSUSCEPTION

• one portion of the gut becomes invaginated within an immediately adjacent segment

• Children between 5 and 10 months of age

• 90% of cases are idiopathic

• upper respiratory tract infection or gastroenteritis may precede

• hyperplasia of Peyer’s patches in the terminal ileum

• Weaning, loss of passively acquired maternal immunity and common viral pathogens

• Meckel’s diverticulum, polyp, duplication,Henoch–Schönlein purpura or appendix

• After the age of 2 years, a pathological lead point is found in at least one-third of affected children

• Adult cases are invariably associated with a lead point

• polyp (e.g. Peutz–Jeghers syndrome), a submucosal lipoma or other tumour

PATHOLOGY

• entering or inner tube

• the returning or middle tube

• the sheath or outer tube (intussuscipiens)

• the apex

• blood supply of the inner layer is usually impaired

• ileocolic colocolic

CLINICAL FEATURES OF INTUSSUSCEPTION

• episodes of screaming and drawing up of the legs

• for a few minutes and recur repeatedly

• child appears pale

• Vomiting

• blood and mucus the ‘redcurrant jelly’ stool

• a lump

• feeling of emptiness in the right iliac fossa (the sign of Dance)

• apex may be palpable or even protrude from the anus

VOLVULUS

• twisting or axial rotation of a portion of bowel about its mesentery

• closed loop of obstruction

• primary or secondary

• congenital malrotation of the gut, abnormal mesenteric attachments or congenital bands

• volvulus neonatorum, caecal volvulus and sigmoid volvulus

CLINICAL FEATURES OF VOLVULUS

• Volvulus of the small intestine

• lower ileum

• Caecal volvulus

• first the obstruction may be partial, with the passage of flatus and faeces

• tympanic swelling in the midline or left side of the abdomen

• Sigmoid volvulus

• intermittent followed by the passage of large quantities of flatus and faeces

• Abdominal distension associated with hiccough and retching

• vomiting occurs late

• Constipation is absolute