Intestinal Obstruction

Question 1

def

Answer 1

obstruction of the normal movement of bowel contents

Question 2

how is bowel obstruction classified

Answer 2

1 according to site
- small bowel
-large bowel
2 partial vs complete
3 simple vs strangulated

Question 3

aetiology

Answer 3

1 simple obstruction (bowel occlusion without vascular compromise)
-intestinal distal to occlusion empties + collapses
-intestine proximal to occlusion dilates with gas + fluid
-with increased distension, intestinal wall blood supply decreases + mucosal ulceration + bowel perforation may occur
2 strangulated obstruction
-blood supply to affected segment is compromised
-leads to impairment of the mucosal barrier with bacteria in the peritoneal cavity causing peritonitis
-unrelieved bowel becomes gangrenous + perforates

Question 4

how are the causes of obstruction classified

Answer 4

1 extramural
-hernia
-volvulus
-external compression by space-occupying lesion
2 intramural
-tumours
-inflammatory strictures (crohns/diverticulitis)
3 intraluminal
-pedunculated tumours
-foreign bodies (gallstones)
-infection
-constipation

Question 5

epi

Answer 5

more common in elderly with increasing adhesions, hernias, malignancy

Question 6

history

Answer 6

1 severe colicky pain
-central -SBO
-lower abdomen - LBO
2 abdominal distension
3 vomiting
-green in early SBO
-faeculent in late LBO
4 absolute constipation

Question 7

examination

Answer 7

1 abdominal distension + tenderness

2 increased bowel sounds (tinkling)

Question 8

investigations

Answer 8

1 bloods
-ABG (lactic acidosis may suggest bowel ischaemia + impending perforation)
-FBC (microcytic anaemia may indication large bowel malignancy)
2 AXR
-diagnosis + localisation of obstruction
-SBO - cross bowel width
-LBO - do not cross bowel width
3 erect CXR
-exclude perforation
4 water soluble contrast enema
-in LBO to localise obstruction

Question 9

management

Answer 9

1 general
-IV fluids + electrolytes
-gastrografin follow through
2 surgical 
-if medical measures fail
-laparotomy/laparoscopy to treat cause
3 endoscopic
-obstructing colonic tumours may be stented
-obstruction secondary to sigmoid volvulus may be treated endoscopically

Question 10

how is gastrografin follow through, therapeutic as well as diagnostic

Answer 10

therapeutic
-hyperosmotic contrast reduces oedema in the bowel wall and relieves obstruction
diagnostic
-shows adhesional obstruction

Question 11

complications

Answer 11

1 dehydration
2 bowel perforation
3 peritonitis
4 toxaemia
5 gangrene of ischaemic bowel wall

Question 12

prognosis

Answer 12

dependent on state of patient and presence of complications