W3 Diseases of the Small Bowel Flashcards
How does small bowel obstruction present on xray?
Looks like person has swallowed fluffy caterpillar
How does small bowel obstruction present?
- pain (colicky, central)
- absolute constipation
- faeculent vomiting
- burping
- abdominal distension
- borborygmi
Describe the pain of bowel obstruction.
Central colicky pain
What builds up in lumen of small bowel?
- Fluid
- Gas
Where does the gas in obstructed small bowel lumen come from?
- Air swallowed
- Gas from fermentation process from bacteria building up from obstruction
Describe what happens pathophysiologically in obstruction of small bowel.
- Fluid + gas build-up
- Ischaemia (occlusion of venous and arterial supplies) + death of tissue
- Perforation
What are the three areas in which a bowel obstruction can come from?
- from within the lumen
- from within the wall
- from outside the wall
What is a bezoar?
ball of hair
What are three examples of causes of bowel obstruction from within the lumen?
- gallstone
- food
- bezoar
What are three examples of causes of bowel obstruction from within the wall?
- Tumour
- Crohn’s
- Radiation strictures (due to radiation enteritis)
What are the two examples of causes of bowel obstruction ?
- adhesions
2. herniation
What happens to the proximal bowel in bowel obstruction?
It dilates and develops altered motility
What is are the two gasses that makes up the majority of the gas that builds up in an obstructed bowel?
- Nitrogen
- Hydrogen Sulphide
What happens to the part of bowel beyond the bowel obstruction?
Carries on as normal until its empty when it contracts and becomes immobile
What is borborygmi?
Noisy gurgly bowel sounds
What is important to figure out in a small bowel obstruction?
What the cause is
What do you look for on abdomen when looking for a a cause of small bowel obstruction?
- scar from previous abdominal surgery
- hernias (femoral/inguinal)
What investigations are carried out in terms of assessing the state of the patient?
- urinalysis (kidney injury?)
- bloods
- gases
What investigations are carried out to confirm the diagnosis?
- AXR
- Contrast CT scan of abdomen
- Gastrograffin studies (rare)
What is gastrograffin?
Oral water-soluble radiological contrast agent
How can bowel obstruction present on AXR with aptient standing?
Air-fluid rainbows
What phrase is associated with treatment for small bowel disease and what does it describe?
- “Drip and suck”
- IV drip and NG tube sucking out fluid and gas
What is treatment for small bowel disease?
- conservative
- IV analgesia
- Fluids with potassium
- catheterise
- Large NG tube (Ryles tube) to suck out
- Antithromboembolism measures
What can perforation lead to in small bowel obstruction and how come it happens?
- Perforation can lead to peritonitis
- Due to necrosis of bowel wall
How can small bowel obstruction lead to sepsis?
Increased bowel wall permeability so microbes can move into peritoneal cavity
Why are patients usually hypokalaemic and alkalotic with small bowel disease?
Loss of K+ ions and HCl due to vomiting
Why treat small bowel obstruction patients with antithromboembolism measures?
As they are at higher risk of DVT due to lying down, being dehydrated and may be more prone due to underlying cause of obstruction
How long is standard drip and suck treatment for?
Up to 72 hrs
What cause of bowel obstruction do you use drip and suck for?
Adhesional
What small bowel obstruction cause will drip and suck not work on?
Hernias
Why would you intervene with drip and suck treatment ?
If signs of:
- strangulation + ischaemia of bowel
- perforation
- closed loop obstruction
What usually causes closed loop obstruction?
Adhesions
What type of surgery is done for small bowel obstruction?
Laparotomy
What can cause mesenteric ischaemia?
- embolus
- thrombosis
What artery supplies the small bowel?
Superior mesenteric artery
How does chronic mesenteric ischaemia present?
Cramping pain usually after eating (like angina of gut)
What happens to the small bowel when mesenteric ischaemia is acute and SMA is obstructed?
Whole small bowel usually gets infarcted and dies
What artery supplies the colon?
Inferior mesenteric artery
What happens to the colon when IMA is blocked?
colon usually lives because of marginal artery
Where does embolus usually come from in mesenteric ischaemia?
Usually from AF and clot forms in left atrium
What is in situ thrombosis usually caused by?
-General gubbedness i.e. patient is trying to die
How can Virchows triad contribute to in situ thrombosis in mesenteric ischaemia?
- dehyrdrated
- hypercoaguable
- local compression of vessels
- vasoconstricting drugs
What is key clue in acute setting to diagnose?
-Little old person
normal AXR
-colicky pain
-clue = lots of analgesia pain out of proportion to clinical findings
Why does alkalosis and hypokalaemia eventually become acidosis and hyperkalaemia and death in mesenteric ischaemia?
Due to anaerobic metabolism and lysis of ischaemic cells which leads to build up of lactic acid and release of intracellular K+
What will gases show in advanced stages of mesenteric ischaemia?
acidosis (low pH, high H+,,
What will bloods usually show in mesenteric ischaemia?
- lactate elevated
- CRP may be normal
- WCC may be slightly raised
What tests diagnose mesenteric ischaemia?
- Gases
- Bloods
- CT angiogram
- at laparotomy
What are the options when treating mesenteric ischaemia?
- resect non-viable intestines
- re-anatomose or staple and plan return if not stable
- SMA embolectomy if possible
- open and close laparotomy
What is a common cause of small bowel haemorrhage?
- Vascular malformations
- Ulcerations
How are vascular malformations treated?
First with interventional radiology e.g. embolisation
Where is Meckel’s diverticulum usually situated?
About 60cm from IC valve
At what age does Meckel’s diverticulum usually present?
Before 2 years of age
What is Meckel’s diverticulum a remnant of?
Omphalomesenteric duct
What is another name for omphalomesenteric duct?
Vitelline duct
What complications can Meckel’s diverticulum cause?
- Bleed (haematochezia)
- Ulcerate
- obstruction
- malingnant change
What is haematochezia?
Passage of fresh blood through the anus
What can ileal diverticulum inflammation mimic in terms of its symptoms?
Appendicitis
Which side of the ileum does Meckel’s diverticulum lie?
antimesenteric border of the ileum i.e. the opposite side to where the mesentery is attached
Where do the left and right vitelline arteries originate from?
Primitive dorsal aorta
What does the right vitelline artery eventually become?
Superior mesenteric artery (that supplies a terminal branch to the diverticulum)
What does the left terminal artery do?
It involutes
Why is Meckel’s diverticulum susceptible to obstruction or infection?
Due to having its own blood supply
