Bowel obstruction Flashcards
What is bowel obstruction?
Mechanical blockage of the bowel whereby a structural pathology physically blocks the passage of intestinal contents
What happens after the bowel segment is occluded?
Gross dilatation of the proximal limb of bowel, increased peristalsis and increased secretion of fluid into the bowel, meaning urgent fluid resuscitation is needed
What is a closed loop obstruction?
If there is a second obstruction proximally e.g. volvulus or in large obstruction with competent ileocaecal valve
What is the problem with a closed loop bowel obstruction?
will continue to distend, stretch and then become ischaemic and perforate
What is functional obstruction/paralytic ileus?
When the bowel is not mechanically blocked but does not work properly due to inflammation, electrolyte derangement or recent surgery
What is the most common cause of bowel obstruction in small bowel?
Adhesions or hernia
What is the most common cause of bowel obstruction in the large bowel?
Malignancy, diverticular disease and volvulus
What are some intraluminal causes of bowel obstruction?
gallstone ileus, ingested foreign body, faecal impaction
What are some mural causes of bowel obstruction?
Carcinoma, inflammatory strictures, intussusception, diverticular strictures, meckels diverticulum and lymphoma
What are some extra mural causes of bowel obstruction?
Hernias, adhesions, peritoneal metastasis, volvulus
What are the clinical features of bowel obstruction?
Abdominal pain (colicky and crampy) Vomiting, abdominal distension and absolute constipation
What is the vomit usually like in bowel obstruction?
Initially gastric contents, then becomes bilious and then faeculent
If an obstruction is more distal, what clinical feature would be present?
constipation
If an obstruction is more proximal what clinical features would be present?
Vomiting
If bowel obstruction is present what would be felt on examination?
Underlying cause may be present, abdominal distension, palpate for focal tenderness including guarding and rebound tenderness
What would percussion reveal in bowel obstruction?
tympanic sound
What would auscultation of bowel obstruction reveal?
tinckling bowel sounds
Do patients with bowel obstruction always how guarding and rebound tenderness?
No unless there is ischaemia
What are the differential diagnosis for bowel obstruction?
Paralytic ileus, toxic megacolon and constipation
What investigations are needed for bowel obstruction?
Urgent bloods and venous blood gas to look for ischaemia (high lactate) and metabolic derangements, CT scan with contrast of the abdomen
Why do a CT with contrast of abdominal X-ray for bowel obstruction?
more sensitive, can differentiate between mechanical and pseudo obstruction, can demonstrate the site and cause of obstruction and may demonstrate metastases
What would the signs of a small bowel obstruction be on a AXR?
Dilated bowel of more than 3cm, central abdominal location, valvulae conniventes visible- lines completely crossing the bowel
What would the signs of a large bowel obstruction be on a AXR?
Dilated bowel of more than 6cm or 9 if caecum, peripheral location, haustral lines visible- lines not completely crossing the bowel
What other imaging technique can be used for bowel obstruction?
contrast fluoroscopy if caused by adhesions from surgery
