Bowel obstruction Flashcards
where can bowel obstruction occur?
= any part of the GI tract
what happens when the Gi tract gets obstructed?
= dilatation of bowel proximal
= peristalsis is distrusted
describe symptoms of upper small bowel obstruction?
- acute presentation
- hours of onset
- large volumes vomited
describe symptoms of distal small bowel/large bowel obstruction?
- colicky abdominal pain and distension
- vomiting (possible ‘faeculent’)
what are symptoms of intestinal obstruction?
- vomiting
- pain
- constipation
- distension
- complete obstruction
- incomplete obstruction
True or false.
The more proximal the obstruction, the earlier vomiting develops.
true
Can vomiting still occur if nothing is taken by the mouth?
= yes.
- GI secretions are continued to b produced
e. g. saliva, gastric, pancreatic, bile, small intestine (up to several litres a day)
what suggests gastric outlet obstruction?
= semi-digested food eaten a day or two previously (no bile)
what suggests upper small bowel obstruction?
= copious bile stained fluid
what suggests distal obstruction?
= thicker, brown, foul-smelling vomitus (faeculent)
what causes pain in intestinal obstruction?
= distension of bowel
= intermittent episodes of colicky pain
what causes constipation in intestinal obstruction?
- propulsion of bowel contents is arrested
- bowel gas is absurd distal to the obstruction
what is absolute consttipation?
neither faeces or flatus (gas) is passed
is pathognomonic of bowel obstruction
why do symptoms tend to develop more gradually in large bowel obstruction?
= due to large capacity of colon and caecum ant here absorptive capacity
what happens in large bowel obstruction if the ileo-caecal valve remain competent?
= backwards flow of accumulated bowel contents is prevented
- the thin walled caecum progressively distends with swallowed air and eventually may rupture: ‘closed loop obstruction’
- can cause rupturing
what happens in large bowel obstruction if the ileo-caecal valve becomes incompetent?
= small bowel distends, delaying onset of symptoms
what happens if there is only partial bowel obstruction?
= clinical features less clearly defined
- vomiting may be intermittent and bowel habit erratic
what does chronic incomplete obstruction lead to?
= hypertrophy of muscle bowel wall proximally
- peristaltic activity in this hypertrophic muscle is responsible for bouts of colicky pain which can be more prominent than in complete obstruction
what are physical signs of intestinal obstruction?
- dehydration, dry mouth, loss of skin turgor, elasticity
- abdominal distension
- visible peristalsis
- relative lack of abdominal tenderness
= obstructing abdominal mass may be palpable
= on percussion centre of abdomen tends to be resonant due to gaseous distension
= groins must be examined for an obstruction hernia
= bowel sounds are high pitched and tinkling, or absent
how would you investigate suspected bowel obstruction?
- supin abdominal X-ray
where do distended small bowel loops and distended large bowels tend to lie in suspected bowel obstruction?
Distended large bowel loops = lie in a central position and have valvulae coniventes
Distended large bowel
= tends to lie in its anatomical position and has hausfrau coli
what may be performed after a X-ray to confirm he diagnosis?
= CT
what are the 4 principles of initial management of intestinal obstruction?
- nil by mouth
- insert IV canula and send blood
- resuscitate with IV fluids, replacing electrolyte losses
- pass a nasogastric tube to decompress the stomach
what are some mechanical causes of bowel obstruction?
- Adhesions or bands
(congenital or resulting from previous abdominal surgery or peritonitis) - Incarcerated abdominal wall hernia
- Internal hernia
- Volvulus
(a mobile loop of bowel that rotates causing obstruction at its neck) - Tumour
- Inflammatory strictures
- Bolus obstruction
- Intussusception
what are examples of inflammatory strictures that act as a mechanical cause of bowel obstruction?
- Crohn’s disease
- diverticular disease
= usually incomplete
what can cause bolus obstruction that acts as a mechanical cause of bowel obstruction?
= something inside lumen of bowel causing obstruction
Examples;
- food
- impacted faeces
- impacted gallstones ileus
- trichobezoar (hair collection)
what is intussusception?
= a segment of bowel wall that becomes telescoped into the segment distal to it
- usually initiated by a mass in the bowel wall: enlargement of lymphatic tissue or tumour
= common in children
what is bowel strangulation?
= a segment of bowel becomes trapped
what are the consequences of bowel strangulation?
- venous return is obstructed
- rising local intra-vascular pressure, therefore, arterial inflow is compromised
- if strangulation is no relieve this will progress to infarction and perforation
what are 2 examples of bowel obstruction?
= paralytic ileus
= pseudo-obstruction
what happens in paralytic ileus?
= disruption of normal propulsive activity of GI tract, duet to failure of peristalsis
what are risk factors for paralytic ileus?
- recent GI surgery
- inflammation with peritonitis
- diabetic keto acidosis
what are symptoms and signs of paralytic ileus?
- similar to bowel obstruction
- pain and high pithced signs are less common
how would you treat paralytic ileus?
= drip and suck while awaiting restoration of peristalsis
what is pseudo-obstruction (Ogilvie’s syndrome)?
= acute dilatation of colon in absence of colonic obstruction in acutely unwell patients
what is pseudo obstruction associated with?
- hip replacement surgery
- coronary artery bypass grafts
- spinal
- pneumonia
- frail/elderly patients
how would you diagnose pseudo-obstruction?
= AXR +/- CT
- confirms gaseous distension to distal rectum
= colon may require colonoscopic decompression if distension is causing pain or respiratory compromise
