Bowel Obstruction Flashcards
how can bowel obstruction be classified?
cause (mechanical or paralytic)
site of obstruction (small/large bowel)
degree of obstruction (partial/complete/closed - emergency)
progression (simple without ischaemia/strangulated with aschaemia)
most common causes of small bowel obstruction?
adhesions (usually from previous surgery)
incarcerated hernias
other causes of small bowel obstruction?
meckels diverticulum stricture (crohns) malignant tumours gall stone ileus superior mesenteric artery syndrome (compression from outside bowel) foreign body internal hernia
paediatric causes of small bowel obstruction
congenital atresia
intussusception
congenital stricture and bands
meckels
most common causes of large bowel obstruction?
malignant tumours
volvulus
other causes of large bowel obstruction?
adhesions
stricture (eg diverticular, IBD)
faecal impaction
foreign body impaction
paediatric causes of large bowel obstruction?
hirschsprung disease (lack of relaxing nerve impulses in lower rectum so muscles dont relax)
congenital strictures and bands
meconium ileus (first stool doesnt pass and causes obstruction)
rectal atresia
possible resulting problems in bowel obstruction?
dehydration and hypovolaemia hypokalaemia hyponatraemia hypochloremia metabolic alkalosis compression of intestinal arterioles/capillaries, veins and lymphatics causing bowel ischaemia, necrosis, perforation, increased permeability, sepsis, metabolic acidosis and hyperkalaemia
cardinal symptoms of bowel obstruction?
abdo pain
vomiting
constipation
abdo distension
pathophysiology of obstruction?
obstruction > increased fluid and gas proximal to obstruction leads to distension > distension causes increased peristalsis to force contents past obstruction leading to colicky pain > severe vomiting from distension and pain leads to dehydration and electrolyte imbalance > increased pressure on wall causes fluid to enter intestine > decreased BP and hypovolaemic shock as more fluid shifts into intestines > continued pressure on intestinal wall causes oedema and ischaemia of wall and decreased peristalsis > prolonged ischaemia causes increased permeability and necrosis of wall, intestinal bacteria and toxins leak into blood and peritoneal cavity causing peritonitis
abdo pain in small vs large bowel obstruction?
small = colicky, periumbilical large = colicky or constant
vomiting in small vs large bowel obstruction?
small = early, large volume and bilious large = late, initially bilious the progresses to faecal
constipation in small vs large bowel obstruction?
small = late large = early
abdo distension in small vs large bowel obstruction?
small = less significant large = early and significant
what history suggests adhesional bowel obstruction?
previous surgery
recurrent episodes
pain comes and goes
history suggestive of obstructed hernia causing obstruction?
history of a lump consistent with hernia
irreducible hernia
history suggestive of colorectal cancer?
elderly change in bowel habit PR bleeding weight loss FH of bowel cancer previous polyps anaemia palpable mass in abdo or on PR exam