3- bowel obstruction = presentation, diagnosis & management Flashcards
what happens to bowel proximal to obstruction?
dilation of bowel proximal to obstruction with air + fluid
is peristalsis disrupted by bowel obstruction?
yes
what is presentation of upper small bowel obstruction?
- acute presentation
- hours of onset
- large volumes vomited
what is presentation of distal small bowel/large bowel obstruction?
- colicky abdominal pain (start & ends suddenly in severe waves)
- distension (bloating)
- vomiting (possible faeculent) →vomiting of material of faecal origin
what are symptoms of intestinal obstruction?
- vomiting
- pain
- constipation
- distension
- complete obstruction
- incomplete obstruction
vomit that’s semi digested food eaten a day or 2 previously suggests what level of obstruction?
suggests gastric outlet obstruction (just after pylorus)
vomit that’s copiously bile-stained fluid suggests what level of obstruction?
suggests upper small bowel obstruction
vomit that’s thicker, brown, foul-smelling vomitus (faeculent) suggests what level of obstruction?
suggests a more distal obstruction
do you have to have eaten something for vomit symptom of intestinal obstruction?
no,
- the more proximal the obstruction, the earlier vomiting develops
- can occur even if nothing is taken by mouth →GI secretions continue to be produced e.g. saliva, gastric, pancreatic, bile
what causes pain in intestinal obstruction?
distension of bowel causes pain (caused by swallowed air & intestinal fluid secreted proximal to an obstruction)
why does pain in intestinal obstruction come in intermittent episodes?
intermittent episodes of colicky pain can occur as peristalsis attempts to overcome the obstruction
what is a specific characteristic of bowel obstruction?
absolute constipation = nothing passing through (gas or poo etc)
(is saying that it’s a specific sign of bowel obstruction)
when is caecum at risk for rupture - what type of obstruction?
closed loop obstruction = large bowel obstruction where there’s a blockage in intestine that forms a loop, this causes caecum to become distended and trapped in loop
what is purpose of ileo-caecal valve?
prevents backward flow of digested material from large intestine to small intestine
- remains competent in about 50% of large bowel obstructions
what is difference in time development of large bowel obstruction compared to small bowel obstruction?
= generally tend to develop more gradually due to large capacity of colon & caecum and their absorptive capacity
what happens if ileo-caecal valve becomes incompetent?
small bowel distends, delaying the onset of symptoms
what is result of incomplete large bowel obstruction?
= clinical features less clearly defined
- chronic incomplete obstruction = leads to gradual hypertrophy of muscle of 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 and elasticity)
- Abdominal distension
- Visible peristalsis
- Relative lack of abdominal tenderness (obstruction with tenderness may indicate bowel strangulation)
what might bowel sounds sound like on examination of intestinal obstrcution?
Bowel sounds are traditionally described as high-pitched and tinkling. In practice they may be absent at the time of auscultation, echoing (cavernous quality), or may sound like water lapping against a boat
what is heard on percussion of abdomen in intestinal obstruction?
the centre of the abdomen tends to be resonant due to gaseous distension
what might be palpable on examination of intestinal obstruction?
abdominal mass
what is most useful imaging for intestinal obstruction and what is seen?
= abdominal x-ray - bowel proximal to obstruction is distended with gas
= can later do CT to confirm diagnosis and look for a cause
what is seen on x-ray imaging of large bowel obstruction?
Distended large bowel tends to lie in its anatomical position and has haustra coli
what is seen on x-ray imaging of small bowel obstruction?
Distended small bowel loops tend to lie in a central position and have valvulae conniventes
what will be seen on CT scan of bowel obstruction?
Transition point on CT scan with distended bowel proximal and collapsed bowel distal to the site of obstruction →A ‘cut off’ will be observed between dilated proximal and collapsed distal bowel at the site of obstruction
what is initial management of intestinal obstruction?
- nothing by mouth
- insert IV cannula and send blood
- resuscitate with IV fluid, replacing electrolyte losses
- pass a nasogastric tube to decompress the stomach
what are mechanical causes of bowel obstruction?
- Adhesions or bands
- Incarcerated abdominal wall hernia
- Internal hernia
- Volvulus
- Tumour
- Inflammatory strictures
- Bolus obstruction
- Intussusception
what are adhesions or bands? (mechanical cause of bowel obstruction)
congenital or resulting from previous abdominal surgery or peritonitis
what are incarcerated abdominal wall hernias? (mechanical cause of bowel obstruction)
and examples?
- involve protrusions through the abdominal wall
- 6 areas= inguinal, femoral, umbilical, paraumbilical, ventral, incisional
what are internal hernia? (mechanical cause of bowel obstruction)
= internal hernias where organs or tissues protrude through openings within the abdominal cavity itself
what are examples of inflammatory strictures? (mechanical cause of bowel obstruction)
like crohn’s or diverticular disease = usually incomplete obstructions
what are bolus obstruction examples?
food bolus, impacted faeces, impacted gallstone ileus (rare), trichobezoar (rare)
what is intussusception?
a segment of bowel wall 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 so it’s lumen becomes obstructed (incarcerated) and blood supply compromised (strangulated)
- venous return is obstructed
- with rising local intravascular pressure subsequently arterial inflow is compromised
what happens if bowel strangulation not relieved?
this will progress to infarction & perforation
what does pain over a hernia mean - what needs to be done?
Pain over a hernia suggests possible strangulation and is a sign requiring urgent surgical intervention.
what are types of adynamic bowel obstruction?
- paralytic ileus
- pseudo-obstruction
what is adynamic bowel obstruction?
Disruption of the normal propulsive activity of the GI tract, due to failure of peristalsis.
what are risk factors for paralytic ileus type of adynamic bowel obstruction?
- Recent GI surgery
- Inflammation with peritonitis
- Diabetic keto acidosis
what are symptoms & signs of paralytic ileus type of adynamic bowel obstruction?
similar to bowel obstruction although pain and high pitched bowel sounds are less common.
what is treatment of paralytic ileus type of adynamic bowel obstruction?
‘drip and suck’ while awaiting restoration of peristalsis
drip = IV fluid + replaced electrolytes
suck = nasogastric tube
what is pseudo-obstruction type of adynamic bowel obstruction?
= Acute dilatation of the colon in the absence of colonic obstruction in acutely unwell patients
- example is ogilvie’s syndrome
what is pseudo-obstruction type of adynamic bowel obstruction associated with?
- Hip replacement surgery
- Coronary Artery Bypass Grafts
- Spinal
- Pneumonia
- Frail / elderly patients
what is involved in treatment & diagnosis of pseudo obstruction type of adynamic bowel obstruction?
- abdominal x-ray +/- CT confirms gaseous distension to distal rectum
- Colon may require colonoscopic decompression if distension is causing pain or respiratory compromise
