Bowel obstruction

Question 1

Cardinal Sx of bowel obstruction

Answer 1

1. Colicky pain
2. Distension
3. Vomiting
   - immediately after ingestion
   - bile stained
   - faeculent -> LBO
4. Constipation
   - need not to be absolute, flatus can pass

Question 2

BO signs on examination

Answer 2

general - visible peristalsis

palpate - increased rigidity, guarding

auscultate - hyperactive, high pitched tinkling bowel sound

Question 3

Causes of SBO

Answer 3

• hernia

- adhesion

Question 4

Causes of LBO

Answer 4

• colon CA
• constipation
• volvulus ; sigmoid, caecal
• diverticular stricture

Question 5

Investigation for BO

Answer 5

AXR -
in SBO; gas-filled dilated bowel in central with volvular conniventes that completely cross lumen
no gas in large bowel

    in LBO; peripheral gas shadow proximal to blockage, dilated bowel > 5 cm width
                  large bowel haustra do not cross all lumen's width

• CXR - free gas under diaphragm for perforation

Question 6

What 3 key decisions need to be made for BO?

Answer 6

1. Where is the obstruction?
   SBO or LBO; refer to AXR and clinical sign (vomiting)
2. paralytic ileus or mechanical obstruction?
   
   • ileus: no pain, bowel sound absent
3. simple, closed loop or strangulated?
   - simple: one obstruction point, no vascular compromise

• closed loop: 2 obstruction points (sigmoid volvulus) = loop of grossly distended bowel,
  risk of perforation (usually at caecum where it’s thinnest and widest; > 12 cm need urgent decompressation)
• strangulated: blood supply compromised; pt more ill than expected; sharper & more localised pain; peritonism; fever and raised WCC

Question 7

Management for BO

Answer 7

depends on cause, site, speed of onset, completeness of obstruction

• strangulation and LBO require surgery
• paralytic ileus and incomplete SBO can be conservatively manage (initially at least)

1. Drip and suck: NGT and IV fluids to rehydrate electrolyte balance
2. analgesia
3. blood test, erect CXR, AXR, catheterise to monitor fluid status
4. further imaging: CT if xray + clinical findings are inconclusive -> find cause and level of obstruction
   colonoscopy in LBO can cause perforation
5. strangulation & closed loop need urgent surgery.
   stent maybe used for colon ca as palliation or as a bridge to surg in acute obstruction