Bowel Obstruction Flashcards
what happens to the bowel proximal to an obstruction
dilatation with air and fluid
how can an upper small bowel obstruction present
acutely, hours of onset, large volumes (of gastric, pancreatic and biliary secretions) vomited
how does a distal/ large bowel obstruction present
colicky abdominal pain and distention, vomiting (possibly faeculent)
what are the symptoms of intestinal obstruction
vomiting, pain (colicky), constipation, distention, complete/ incomplete obstruction
what determines when vomiting develops
hoe proximal the obstructions- the more proximal the earlier the vomiting
what causes vomiting when nothing is taken by mouth
GI secretions- saliva, gastric, pancreatic, bile, small intestine
what about the vomitus gives clues to the level of obstruction
nature of vomitus
vomitus: what does semi digested food eaten a day/ two before suggest
no bile, obstruction in gastric outlet
vomitus: what does copious bile stained fluid suggest
upper small bowel obstruction
vomitus: what does thicker, brown, foul-smelling vomitus suggest
faeculent vomiting, a more distal obstruction
what causes pain in bowel obstruction
distention of the bowel, intermittent episodes of colicky pain ( as peristalsis tries to overcome the obstruction)
what causes distention of the bowel
swallowed air and intestinal fluid secreted proximal to an obstruction
describe the onset of symptoms in large bowel obstructions
more gradually as large bowel has more capacity and absorptive capacity
what is prevented in large bowel obstruction if the ileocaecal valve is competent
backflow of accumulated contents
what is a closed loop obstruction and what can is cause
when thin walled caecum progressively distends and eventually may rupture
why is the caecum at most risk of rupturing
thin walls
what happens if the ileoceacal valve becomes incompetent
small bowel distends and the onset of symptoms is delayed
what are the symptoms of incomplete bowel obstruction
intermittent vomiting and erratic bowel habit
what does chronic incomplete obstruction leads to
gradual hypertrophy of the muscle of the bowel proximally- creates pain during peristalsis in this area
what are the physical signs of intestinal obstruction
dehydration, abdominal distention, visible peristalsis, relative lack of abdominal tenderness, possible palpable mass, resonant to percussion, possible hernia, high pitched- tinkling bowel sounds
what investigations should be done initially
supine abdo x ray- bowel proximal will be distended with gas
what do erect x rays show
air fluid levels- not done now
what does distended bowel look like on x ray
black with air, in anatomical position, has haustra coli
what is a CT used for
to look for cause and find transition site between distended bowel proximal and collapsed bowel distal
how is an intestinal obstruction initially managed
nil by mouth, IV cannula, fluid resus, replace electrolytes, NG tube to decompress the stomach
what are the mechanical causes of bowel obstruction
adhesions or bands (congenital or post op or peritonitis), hernia abdo wall or internal), volvulus, tumour, inflammatory strictures, bolus obstruction, intussusception
how are adhesions or bands treated
drip and suck
what are the types of abdo all hernias that can become incarcinated and cause bowel obstruction
inguinal, femoral, umbilical, paraumbilical, ventral, incisional
what part of the bowel is most likely to get a volvulus
sigmoid
how is a volvulus treated
colonscope
what can happen when the bowel perforates
peritonitis
what can cause inflammatory strictures
crohns disease, diverticular disease
where are inflammatory strictures most common
in small bowel
what can cause bolus obstruction
food bolus, impacted faeces, gallstone ileus, tichobezor (hairball)
how does a gall stone get into the ileum
fistula
what is intussusception
when a segment of bowel wall becomes telescoped into the segment distal to it
what initiates intussusception
mass- enlargement of lymphatic tissue or tumour
what happens to blood flow when bowel become obstructed
venous return is obstructed, rises local intra vascular pressure, arterial flow is compromised
what happens if strangulation is not relieved
infarction and perforation
what is the venous pressure of the gut
14 mmHg
what does pain over a hernia suggest
bowel stangulation, required urgent surgical intervention
what is adynamic bowel obstruction
paralytic ileus (post op) or pseudo-obstruction, failure of peristalsis
what can cause a aparalytic ileus
recent GI surgery, inflammation with peritonitis, diabetic keto acidosis
why dont you get colick in paralytic ileus
bowel is paralytic
how do you treat a paralytic ileus
drip and suck
what is ogilvies syndrome
pseudo-obstruction acute dilatation of the colon in the abscence of colonic obstruction (disruption of autonomic activity of the bowel)
what is pseudo-obstruction associated with
hip replacement, CABG, spinal fracture, pneumonia, frail, eldery
how do relieve pseudo-obstruction
colonoscopic depression
