Pathology of intestinal obstruction

Question 1

What could be causing intraluminal obstruction?

Answer 1

Tumour (carcinomas and lymphoma)
Diaphragm disease
Meconium ileus
Gallstone ileus

Question 2

What is diaphragm disease?

Answer 2

Fibrous diaphragm structure across bowel caused by fibrous scarring mainly from NSAIDs having contact with wall. Not fully understood.
Mainly in small bowel, difficult to get to.

Question 3

What is gallstone ileus?

Answer 3

Large gallstone erodes through gallbladder and into small bowel.
Rare.

Question 4

What are causes of intramural obstruction?

Answer 4

Inflammation (Crohn’s disease and diverticulitis)
Tumours
Neural (Hirschsprung’s disease)

Question 5

Crohn’s disease

Answer 5

Inflammation causes fibrosis in wall of bowel.
Non-caseating granulomas.

Question 6

Diverticular disease

Answer 6

Diverticulum are outpouchings of the mucosa. Typically in sigmoid colon. Very common, doesn’t always cause problems. Can become inflamed and perforate. Linked to low fibre diet causing increased pressure. Outpouchings into muscularis at points of weakness.
Blind-ending sac which can fill with faeces and cause inflammation =diverticulitis. Destroy wall of mucosa and cause perforation, then faeces can enter peritoneal cavity causing peritonitis and sepsis.
Inflammation also causes fibrosis and can cause obstruction.

Question 7

Intramural cancer

Answer 7

Tumour of stroma cells/gut wall causing obstruction.

Question 8

What is Hirschsprung’s disease

Answer 8

Occur in babies.
Nerves in gut so faeces is pushed rhythmically to exit. In Hirschsprung’s disease have aganglionic segment so lower end doesn’t move in, therefore no movement of faeces.

Question 9

What are causes of extraluminal obstruction?

Answer 9

Adhesions, volvulus, tumour (peritoneal deposits)

Question 10

What are adhesions

Answer 10

Bands of fibrous tissue between loops of bowel. Often result of surgery. Used to be talc on surgeon’s gloves that would induce fibrosis.

Question 11

What is volvulus

Answer 11

Primarily sigmoid colon, long mesentery, can twist on itself, self-obstructs. Can be intermittent.

Question 12

Peritoneal tumour

Answer 12

Invasion of serous membrane lining the peritoneal cavity by malignant cells
Often can spread from ovarian cancer.

Question 13

What is Small Bowel Obstruction (SBO)?

Answer 13

Mechanical blockage of the small intestine

Form of intestinal failure, inability of the gut to absorb necessary water, macronutrients, micronutrients and electrolytes sufficient to sustain life and requiring intravenous supplementation or replacement.

Question 14

absolute constipation

Answer 14

No pooing or farting at all!

Question 15

Small bowel obstruction is the most common indication for emergency l_____

Answer 15

laparotomy

Question 16

Why do you get cholic pain with SBO?

Answer 16

Smooth muscle is really working hard (also can get with biliary cholic, ureteric obstruction, labour during birth)

Question 17

What is are common symptoms of SOB

Answer 17

Constipation, cholic pain, distension, vomiting

Question 18

What are causes of SBO

Answer 18

Compression: adhesions, tumour, hernia

Luminal: tumour, foreign body (ingested or gallstone), stricture (inflammatory, malignant, scarring/surgical)

Lack of peristalsis: drugs (opioids), electrolytes, neurological, severe illness/post operative)

Question 19

What is a hernia?

Answer 19

An internal part of the body pushes through a weakness in the muscle or surrounding tissue wall. May notice a swelling or lump which often can be pushed back in or disappears when you lie down.

Question 20

How to investigate SBO?

Answer 20

Full blood count
U&E (and Ca2+, Mg+, PO4 2- and K+)
Lactate
C-reactive protein
Abdominal X-ray
CT scan
Endoscopy if need tissue

Question 21

Treatment for bowel obstruction

Answer 21

Decompression - nasogastric tube (prevent vomiting so won’t aspirate) and urinary catheter

Fluid replacement

Electrolyte replacement

Nutrition

Stent

Surgery (generally open, sometimes keyhole)

Analgesia

Question 23

Why is large bowel obstruction often closed loop?

Answer 23

Other end of large bowel is ileo-caecal valve, won’t let stuff back. Might not be vomiting but be distended and in pain.