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9. GI system > Intestinal Obstruction > Flashcards

Intestinal Obstruction Flashcards

1
Q

Define an intestinal obstruction.

A

Arrest/blockage of onward propulsion of intestinal contents through the bowel.
Can be a surgical emergency.

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2
Q

Classifications of obstruction according to:
- Site.

A

Large bowel/small bowel/gastric

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3
Q

Classifications of obstruction according to:
- Extent of luminal obstruction.

A
  • Partial
  • Complete - volvulus can result in this, resulting in overflow and sickness
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4
Q

Classifications of obstruction according to:
- Mechanism.

A
  • Mechanical
  • True (intraluminal/extraluminal)
  • Functional:
  • Paralytic ileus - a dynamic bowel due to the absence of normal
    peristaltic contractions, caused by abdominal surgery or acute
    pancreatitis
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5
Q

Classifications of obstruction according to:
- Pathology.

A
  • Simple
  • Closed loop
  • Strangulation
  • Intussusception - one hollow structure into its distal hollow structure, usually seen in children as bowel is softer
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6
Q

Intestinal obstruction: what is intussusception?

A

Intussusception is when part of the intestine invaginates into another section of the intestine -> telescoping. It is caused by force in-balances.

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7
Q

What are most intestinal obstructions due to?

A

Most intestinal obstruction is due to a mechanical block

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8
Q

Name the 3 broad categories that describe the causes of intestinal obstruction.

A
  1. Blockage.
  2. Contraction.
  3. Pressure.
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9
Q

Intestinal obstruction: give 3 causes of blockage.

A
  1. Tumour.
  2. Diaphragm disease.
  3. Gallstones in ileum (rare).
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10
Q

Intestinal obstruction: what is thought to cause diaphragm disease?

A

NSAIDS.

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11
Q

Intestinal obstruction: give 3 causes of contraction.

A
  1. Inflammation.
  2. Intramural tumours.
  3. Hirschprung’s disease.
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12
Q

Intestinal obstruction: what can cause inflammation to cause contraction for intestinal obstruction?

A
  1. Crohn’s disease.
  2. Diverticulitis.
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13
Q

Describe how Crohn’s disease can cause intestinal obstruction.

A

Crohn’s disease -> fibrosis -> contraction -> obstruction.

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14
Q

What is Hirschprung’s disease?

A

A congenital condition where there is a lack of nerves in the bowel = so without complete innervation of the colon to rectum.

  • Motility is affected
  • Results in gut dilatation and the filling of faeces
  • Since there are no ganglion cells, no peristalsis or movement of content
  • Results in gross dilatation and obstruction of the bowel
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15
Q

Intestinal obstruction: give 3 causes of pressure.

A
  1. Adhesions.
  2. Volvulus.
  3. Peritoneal tumour.
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16
Q

Intestinal obstruction: what are adhesions?

A

Adhesions often form secondary to abdominal surgery.

It is the sticking together of abdominal structures to one another, bowel loops, omentum, other solid organs or the abdominal wall
by fibrous tissue, leading to the bowel being pulled and distorted.

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17
Q

Intestinal obstruction: what causes adhesions?

A

Adhesions often form secondary to abdominal surgery.

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18
Q

Intestinal obstruction: what is volvulus?

A

Volvulus is a twist/rotation in the bowel; closed loop obstruction. There is a risk of necrosis.
- Looks like a coffee-bean!

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19
Q

Intestinal obstruction: which areas of the bowel are most likely to be affected by volvulus?

A

Volvulus occurs in free floating areas of the bowel e.g. bowel with mesentery. The sigmoid colon has a long mesentery and so can twist on itself.

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20
Q

What is the most common cause of obstruction in adults?

A

Adhesions

21
Q

Name 3 categories of bowel obstruction.

A
  1. Small bowel obstruction (most common)
  2. Large bowel obstruction
  3. Pseudo-obstruction
22
Q

Which is more common: small bowel obstruction or large bowel obstruction?

A

Small bowel obstruction is more common; it makes up 75% of intestinal obstruction.

23
Q

Give 4 common causes of small bowel obstruction in adults.

A
  1. Adhesions from previous abdominal / gynecological surgery.
  2. Hernias.
  3. Crohn’s disease.
  4. Malignancy.
24
Q

Give 3 common causes of small bowel obstruction in children.

A
  1. Appendicitis.
  2. Volvulus.
  3. Intussusception.
25
Q

Give 5 symptoms of small bowel obstruction.

A
  1. Colicky abdominal pain (pain higher up)
  2. Abdominal distension (less severe than LBO)
  3. Vomiting first (bilious)
  4. Followed by constipation with no pass of wind
  5. ‘Tinkling’ bowel sounds
  6. Tenderness
  7. Nausea + anorexia
26
Q

Would dilatation, distension and increased secretions be seen proximal or distal to an intestinal obstruction?

A

Proximal.

27
Q

Give 4 signs of small bowel obstruction.

A
  1. Vital signs e.g. increased HR, hypotension, raised temperature.
  2. Tenderness and swelling.
  3. Resonance.
  4. Bowel sounds.
28
Q

What investigations might you do in someone who you suspect to have a small bowel obstruction?

A
  1. Take a good history - ask about previous surgery (adhesions)!
  2. Bloods - FBC (essential!), U+E, lactate.
  3. 1st line: Abdominal XRay (dilation of the small bowel >3 cm, coiled-spring appearance )
  4. Gold standard: CT abdomen and pelvis with/without contrast
29
Q

What is the management of stable patients with small bowel obstruction?

A

Conservative management (stable patients):
A-E assessment.
‘Drip and suck’:
- Insert IV cannula → Resuscitate with IV fluids
- Nil-by-mouth (NBM)
- Insert nasogastric (NG) tube to decompress stomach
- Catheter (monitor urine output)
- Analgesia, antiemetics, antibiotics

30
Q

What is the management of unstable patients with small bowel obstruction?

A

Surgical (unstable patients):
Treat according to cause
- Laparotomy
- Adhesiolysis for adhesions
- Hernia repair
- Tumour resections
- Bowel resection

31
Q

Give 2 common causes of large bowel obstruction.

A
  1. Colorectal malignancy.
  2. Sigmoid volvulus (especially in the developing world).
  3. Diverticulitis.
32
Q

Give 5 symptoms of large bowel obstruction.

A
  1. Tenesmus.
  2. Constipation first
  3. Follwed by vomiting (initially bilious, then faecal fluid)
  4. Continuous Abdominal discomfort/pain
  5. Severe abdominal distension
  6. Bloating.
  7. Absent bowel sounds.
  8. Weight loss.
33
Q

What investigations might you do in someone who you suspect to have a large bowel obstruction?

A
  1. 1st line: Abdo XRay
    • Dilation of the large bowel > 6cm
    • Dilation of the caecum > 9cm
  2. Gold standard: CT of the abdomen and pelvis with contrast
  3. Digital rectal exam:
    • Empty rectum
    • Hard stools
    • Blood
  4. FBC = essential - see low Hb sign of chronic occult blood loss
34
Q

What is the management of stable patients with large bowel obstruction?

A

Conservative management (stable patients):
A-E assessment.
‘Drip and suck’:
- Insert IV cannula → Resuscitate with IV fluids
- Nil-by-mouth (NBM)
- Insert nasogastric (NG) tube to decompress stomach
- Catheter (monitor urine output)
- Analgesia, antiemetics, antibiotics

35
Q

What is the management of unstable patients with large bowel obstruction?

A

Surgical (unstable patients):
Treat according to cause
- Laparotomy
- Adhesiolysis for adhesions
- Hernia repair
- Tumour resections
- Bowel resection

36
Q

Give 3 consequences of untreated intestinal obstructions.

A
  1. Ischaemia.
  2. Necrosis.
  3. Perforation.
37
Q

Give 2 indications for the need of immediate surgical intervention in someone with a small bowel obstruction.

A
  1. Signs of perforation (peritonitis).
  2. Signs of strangulation.
38
Q

What is the difference between SBO and LBO for the symptom of pain?

A

SBO: colicky abdominal pain
LBO: continuous abdominal pain

39
Q

What is the difference between SBO and LBO for the symptom of vomiting?

A

SBO: early onset bilious vomiting
LBO: late onset vomiting, first bilious followed by faecal

40
Q

What is the difference between SBO and LBO for the symptom of constipation?

A

SBO: late onset
LBO: early onset

41
Q

What is the difference between SBO and LBO for the symptom of abdominal distension?

A

SBO: less severe
LBO: significant

42
Q

What is the difference between SBO and LBO for the symptom of bowel sounds?

A

SBO: ‘tinkling’ bowel sounds
LBO: absent

43
Q

What is the difference between SBO and LBO for the abdominal X-ray?

A

SBO:
Dilation of the small bowel >3cm
Coiled-spring appearance
Centrally located multiple dilated loops of gas filled bowel (arrowheads)
Valvulae conniventes (arrow) are visible - confirming this is small bowel

LBO:
Dilation of the large bowel >6cm or the caecum >9cm

44
Q

What is pseudo-obstruction?

A

Also known as Ogilvie syndrome

Clinical picture mimicking colonic dilation + obstruction but with no mechanical cause of obstruction.

45
Q

Give 4 causes of pseudo-obstruction.

A
  1. Post-operative (paralytic ileus)
  2. Medications (opioid, calcium channel blockers, antidepressants)
  3. Neurological (Parkinson’s, multiple sclerosis, Hirschsprung’s)
  4. Electrolyte imbalance
  5. Recent trauma/surgery
46
Q

Explain the pathophysiology of pseudo-obstruction.

A

Parasympathetic nerve dysfunction → absent smooth muscle
Complication: bowel ischaemia and perforation

47
Q

What investigations might you do in someone who you suspect to have a pseudo-obstruction?

A
  1. 1st line: Abdominal X-ray (megacolon → dilation > 10cm)
    - Shows a gas-filled large bowel
  2. Gold standard: CT of the abdomen and pelvis with contrast (no transition zone)
48
Q

What is the management for pseudo-obstruction?

A
  1. ‘Drip and suck’ management
  2. Treat underlying cause e.g. withdrawal of opiate analgesia
  3. IV neostigmine
  4. Surgical decompression for unstable patients (caecostomy, ileostomy)

9. GI system (15 decks)

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