6.7 Obstruction of the Gastrointestinal Tract Flashcards
What are the three categories of causes of bowel obstruction. Provide examples of each
- Extraluminal: adhesions to other structures, volvulus [which is…], hernia
- Within the intestinal wall: tumour, stricture [e.g. crohn’s], haematoma
- Intraluminal: intussusception, gallstone, foreign bodies
Describe the progression of small bowel obstructions
- Initial obstruction
- Distension
- GI wall becomes oedematous and loses absorptive function
- Ischaemia (blockage of blood supply due to swelling, especially in closed loops)
- Ischaemic necrosis, leading to perforation
Describe the character of colicky pain. What does it indicate?
- Colicky pain is severe cramping pain
- Comes and goes suddenly in waves, as per regular bowel movements
- Tends to indicate obstruction of a hollow, muscular tube
How does abdo distension/vomiting (+ contents of vomit) change depending on the location of a small bowel obstruction
- Higher obstruction makes vomiting more likely, and distension less likely (closer to stomach, easier exit)
- Lower obstruction makes vomiting less likely, and distension more likely
- In lower SI obstruction, vomit may have a more faecal appearance
What imaging investigations might we perform to assess for small bowel obstruction?
- AXR
- CT abdomen
Where does large bowel obstruction usually occur? Why?
- Occurs more commonly on left side
- At this point, more water has been resorbed, so stool is more solid
Signs/symptoms of small bowel obstruction on Hx/exam
Hx:
- Colicky abdominal pain
- Nausea/vomiting
- Abdominal distension
- Constipation
Exam:
- Tenderness
- Scars (?post-operative), herniae
How do the signs/symptoms of large bowel obstruction differ from those of small bowel obstruction
- Slower onset of symptoms (slower transport of stuff through the colon than SI)
- Less pain
- Less vomiting (farther to the mouth)
What are some common causes of large bowel obstruction?
- Colorectal cancer (always screen)
- Volvulus (twisting)
- Stricture (IBD, ischaemia, diverticulitis)
- Hernia, adhesions
- Faeces
What is post-operative ileus? What other pathologies can cause ileus?
- Loss of regular GI motility following surgery (more common after open surgery)
- Caused by inhibitory neural reflexes in response to abdominal inflammation
- Can also be caused by pancreatitis, retroperitoneal bleed, spinal cord injury (all sources of inflammation)
Ogilvie’s syndrome is also called… It typically occurs in settings such as…
- Acute colonic pseudo-obstruction
- Occurs in very sick hospitalised patients (trauma, infectoin, dardiac disease etc.), metabolic disturbance, and medications such as anticholinergics (?dementia)
2 causes of toxic megacolon are…
- IBD
- C Diff infection
Paraneoplastic syndromes occur when…
Anti-cancer components of the nervous system attack the body itself
How can bowel obstruction cause infection?
- Bowel perforation 2° to ischaemic necrosis
- Infection and peritonitis
What are 3 questions we might ask if we suspect small bowel obstruction?
- Does vomiting relieve pain? (decompresses)
- Is this a recurrent problem? (can be)
- Any lumps or bumps (?malignancy, hernia)
