Bowel Obstruction Flashcards
Bowel obstruction can either be mechanical or Ileus. What is Ileus?
Hypomobility in the absence of mechanical obstruction
Is gallstone Ileus a type of mechanical obstruction or Ileus (if ileus, explain the pathophysiology behind it)
Mechanical obstruction
The bowel is now partially obstructed by a faecolith. If this is not managed, how will this progress?
Partial obstruction -> complete obstruction -> Closed loop obstruction (with the ileocecal valve) -> Bowel ischaemia -> Infection and necrosis
20% of colorectal cancer present with large bowel obstruction. When taking a history of bowel obstruction, you should make sure to ask about both the stool and the gas. If patient doesnt have either it is called….? Whats another name for that?
Absolute constipation
Obstipation
What is the most common cause of an aganglionic segment in adults and in children?
Adults: Chagas disease (also achalasia-idiopathic)
Children: Hirschprung (a/w T21)
What drugs most commonly cause constiption?
Opioids and anticholinergics
What is superior mesenteric artery syndrome?
It is when the duodenum is compressed between the SMA and the aorta. Presents with irretractable vomiting that is persistent and resistant to treatment
A patient presents with constipation, with no bowel motion in the past 3 days. On exam their abdomen is extended. They have been vomiting for the past 24 hours after every meal. What are your differentials?
Intraluminal -> Faecolith/faecal impaction, Gallstone Ileus, Foreign body
Mural:
Mechanical-> Tumours, Strictures, volvulus, intussusseption, Diverticula
Functional (ileus) -> Post-op, Aganglionic segments, Atresia, Bowel ischaemia (mesenteric ischaemia, ischaemic colitis)
Extramural ->Adhesions, hernias (incl. oesophageal), endometriosis, drugs (opioids, anticholinergics), Superior mesenteric artery syndrome
List the main signs and symptoms you would need to elicit in a history and an ideal exam.
Small bowel loops are called
Large bowel loops are called
SB = Valvulae conniventes
LB = Haustrations
What is being shown in this image?
PFA of small bowel obstruction
Stack of coins => Valvulae conniventes
What imaging investigations would you conduct to diagnose SBO
!!Erect/Decubitus PFA with Gastrograffin (given 2-5 hours before)
CT abdomen with contrast
Why must the PFA of SBO be taken in an upright or decubitus position for bowel obstruction
Now you may say for pneumoperitoneum but we also ordered the CXR so its not the actual reason
The real reason is to see air fluid levels. If the patient is supine, itll just be mixed and homogenous
You are trying to look for air fluid levels on the erect/decubitus PFA and youre finding it inconclusive. Your order a CT abdomen now.
Will you order it with or without contrast?
What position should the patient be to ensure you can visualise the air-fluid levels
Depends: If it is unnecessary or contraindicated then a non-contrast CT is used. You are able to obtain most findings with that. Contrast CT can be used in addition for particular relevant concerns
1) IV to visualise blood supply to see if there is vascular compromise or ischaemia as well as if there is bleeding (and can also see perforation as it would for PUD)
2) Oral contrast in the case of fistula or perforations may also be relevant
There is only 1 position in the CT and you can obtain the air fluid levels very clearly.
What sizes are you looking for to suspect bowel obstruction on PFA?
SB = VC = >3cm
LB = Haustrations = >6cm
Caecum = >9cm
What findings are you looking for on a PFA of bowel obstruction
1) Pneumoperitoneum
2) Dilated SB or LB loops (VC or haustrations) over the 3,6,9 rule proximal to obstruction
3) Air fluid levels
4) Gut wall thickening
List the imaging investigations you would like to order for a patient presenting with bowel obstruction AND the findings you are looking for.
Managing SBO is based on the cause
What is the general management of any obstruction?
What is the specific management for the following:
Tumour:
Strictures:
Adhesions:
Volvulus:
Tumour perfect answer:
Staging -> Pre-assessment for treatment options -> MDT -> Discuss with patient -> Resection with R0 margins
If palliative -> Stenting +/- debulking procedure
