Pathology of intestinal obstruction Flashcards
What could be causing intraluminal obstruction?
Tumour (carcinomas and lymphoma)
Diaphragm disease
Meconium ileus
Gallstone ileus
What is diaphragm disease?
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.
What is gallstone ileus?
Large gallstone erodes through gallbladder and into small bowel.
Rare.
What are causes of intramural obstruction?
Inflammation (Crohn’s disease and diverticulitis)
Tumours
Neural (Hirschsprung’s disease)
Crohn’s disease
Inflammation causes fibrosis in wall of bowel.
Non-caseating granulomas.
Diverticular disease
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.
Intramural cancer
Tumour of stroma cells/gut wall causing obstruction.
What is Hirschsprung’s disease
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.
What are causes of extraluminal obstruction?
Adhesions, volvulus, tumour (peritoneal deposits)
What are adhesions
Bands of fibrous tissue between loops of bowel. Often result of surgery. Used to be talc on surgeon’s gloves that would induce fibrosis.
What is volvulus
Primarily sigmoid colon, long mesentery, can twist on itself, self-obstructs. Can be intermittent.
Peritoneal tumour
Invasion of serous membrane lining the peritoneal cavity by malignant cells
Often can spread from ovarian cancer.
What is Small Bowel Obstruction (SBO)?
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.
absolute constipation
No pooing or farting at all!
Small bowel obstruction is the most common indication for emergency l_____
laparotomy
Why do you get cholic pain with SBO?
Smooth muscle is really working hard (also can get with biliary cholic, ureteric obstruction, labour during birth)
What is are common symptoms of SOB
Constipation, cholic pain, distension, vomiting
What are causes of SBO
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)
What is a hernia?
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.
How to investigate SBO?
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
Treatment for bowel obstruction
Decompression - nasogastric tube (prevent vomiting so won’t aspirate) and urinary catheter
Fluid replacement
Electrolyte replacement
Nutrition
Stent
Surgery (generally open, sometimes keyhole)
Analgesia
Why is large bowel obstruction often closed loop?
Other end of large bowel is ileo-caecal valve, won’t let stuff back. Might not be vomiting but be distended and in pain.
