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Gastrointestinal > Intestinal Obstruction > Flashcards

Intestinal Obstruction Flashcards

1
Q

What is intestinal obstruction?

A

A blockage to the transit of intestinal contents through the gut

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2
Q

What are the 3 categories of obstruction?

A
  1. Intra-luminal
  2. Intramural
  3. Extra-luminal
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3
Q

What are some causes of intra-luminal obstruction?

A

Tumours

Gallstones

Meconium disease: first stool of neonate can cause blockage

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4
Q

What are some causes of intramural obstruction?

A

Inflammation can lead to fibrosis and therefore obstruction: Crohn’s or diverticulitis

Tumours within bowel wall

Neural: Hirschprung’s disease

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5
Q

What is Hirschprung’s disease?

A

Neonates can be born without innervation all the way through the bowel.
They have an aganglionic segment of bowel

The faeces just doesn’t move down

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6
Q

What are some extra-luminal causes of obstruction?

A

Adhesions

Volvulus: twist in bowel

Tumour in peritoneum can press on bowel obstructing it

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7
Q

What are adhesions? Why do they occur?

A

They are when scar tissue forms between the wall of one segment of the bowel and the wall of another segment.

Two segments become attached when they shouldn’t be

Due to surgery usually

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8
Q

How do adhesions cause obstruction?

A

They cause bits of the bowel to become twisted and trapped so faeces can’t travel through easily

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9
Q

What type of cancer usually causes peritoneal tumours?

A

Ovarian

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10
Q

What is a volvulus? And which part of the bowel are they common in?

A

A twist in the bowel

Parts of the colon that have a mesentery: sigmoid or caecum

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11
Q

What’s the difference between mechanical and functional obstruction?

A

Mechanical: an actual obstruction, something is physically blocking bowel

Functional: paralysis or problem with nerves supplying bowel means no peristalsis so no movement of faeces

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12
Q

What is a pseudo-obstruction?

A

Obstruction caused by something unknown

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13
Q

What are the complications that can arise from untreated intestinal obstruction?

A

Ischaemia
Necrosis
Perforation

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14
Q

What are the clinical features of intestinal obstruction?

A

Vomiting (different types depending on site of obstruction)

Colicky pain

Constipation or no faeces or flatus passed at all

Distention

Tenderness on pressure

Anorexia

Hypovolaemia

Tinkling bowel sounds

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15
Q

What type of vomiting would you see with obstruction:

  • high up near stomach
  • in the colon?
A

Near stomach = projectile vomiting
It would occur sooner

In colon = faeculent vomiting
It would occur later

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16
Q

What is meant by ‘proximal dilatation’?

A

The section of bowel just above the obstruction becomes dilated.

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17
Q

Why does proximal dilation occur in the:

  • small bowel
  • large bowel?
A

Small bowel:
there’s a build up of secretions and swallowed air that can’t pass through

Large bowel:
bacterial fermentation releases gases that can’t escape

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18
Q

Why does intestinal obstruction cause decreased blood volume?

A

The blockage causes fluid and electrolyte imbalance, leading to hypovolaemia

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19
Q

What are the causes of small bowel obstruction (SBO) in adults?

A

Adhesions (due to past surgery)
Hernia (often incisional)
Crohn’s
Malignancy

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20
Q

What are the causes of small bowel obstruction (SBO) in children?

A

Appendicitis

Developmental defects

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21
Q

What types of surgery carry a risk of adhesions developing?

A

Pelvic
Gynaecological
Colorectal

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22
Q

How can hernias cause damage to small bowel?

A

They can cause strangulation of the bowel as it is forced through a small space it shouldn’t go

23
Q

What are some risk factors for getting an incisional hernia?

A

Smoking
Obesity
Cutting across natural lines of muscle

24
Q

What is intesussception?

A

The telescoping (invagination) of one bit of intestine into another

25
Q

Which medical conditions is intesussception associated with?

A

Cystic fibrosis

Henoch-Schonlein purpura (inflammation of small blood vessels)

26
Q

What causes intesussception?

A

An imbalance of the longitudinal forces along the intestinal wall

A disorganised pattern of peristalsis

27
Q

What is the intussusceptum?

A

The invaginating portion of bowel in an intesussception

28
Q

What is the intussuscipiens?

A

The receiving portion of bowel in an intesussception

29
Q

While examining the abdomen of a patient with intestinal obstruction, you hear dull sounds? What does this mean?

A

There is fluid filling the bowel in the area you are examining

30
Q

While examining the abdomen of a patient with intestinal obstruction, you hear tympanic sounds? What does this mean?

A

There is gas filling the bowel in the area you’re examining

31
Q

What sort of bowel sounds do you hear in intestinal obstruction?

A

Tinkling

These disappear at late stages

32
Q

What investigations should you do in a suspected SBO?

A

Blood tests:
FBC, U+E, lactate (increased in some cases of obstruction)

X-ray: look for build up of gas, faeces and ischaemia

CT: use contrast to show up blockage

Ultrasound + MRI

33
Q

Which people is intesussception most commonly seen in?

A

Infants + toddlers

34
Q

What would you find by palpation in a patient with intesussception?

A

Sausage shaped mass in right upper quadrant

35
Q

Management of SBO?

A

Fluid resuscitation

Insert NG tube to decompress bowel (removal of contents by suction)

Analgesia + anti-emetic

Consider surgery

Antibiotics

36
Q

When should you immediately operate in SBO?

A

Signs of strangulation

Perforation + peritonitis

37
Q

What can you to surgically to treat SBO?

A

Remove the cause of obstruction

Bypass the segment

Resection

Exteriorisation (stoma bag)

38
Q

What are the causes of large bowel obstruction?

A

Malignancy
Volvulus
Strictures (narrowing)
Congenital fault

39
Q

Describe the progression of obstruction to peritonitis.

A

Obstruction

Proximal dilatation

Increased colonic pressure = decreased mesenteric blood flow

Mucosal oedema caused by fluids + electrolytes in the lumen

Arterial blood supply is compromised

Mucosa becomes ischaemia

Ulceration

Necrosis

Perforation

Bacteria escape to peritoneum

40
Q

What happens if the ileocaecal valve is incompetent?

A

It won’t open and you’ll get faeculent vomiting

41
Q

Why would a volvulus occur?

A

Sometimes the bowel just twists on itself spontaneously!

42
Q

What is a closed loop obstruction?

A

A 360 degree twist/volvulus

43
Q

Why do loop obstructions perforate?

A 
Increase in pressure in section
Impaired blood flow
Ischaemia
Necrosis
Perforation
44
Q

In colorectal tumours, where does perforation occur?

A

At the site, rather than proximally

Because perforation is caused by local invasion of the tumour and inflammation of area

45
Q

Volvuli present suddenly. True or false?

A

True

46
Q

What would you find on examination of someone with LBO?

A

Distension
Resonance
Palpable mass

Digital rectal examination:

  • empty rectum
  • hard stools
  • blood
47
Q

Investigation of LBO?

A

Bloods: FBC, U+E, lactate

X-ray + CT

Contrast enema

Endoscopy: look at mucosa, risk of perforation, can be therapeutic

48
Q

What is the significance of lactate in intestinal obstruction?

A

High levels indicate some types of bowel obstruction

49
Q

What signs are seen on AXR in large bowel obstruction?

Where would obstruction be and what would it be if you saw these signs?

A

Coffee bean
Bird of prey

Sigmoid volvulus

50
Q

How would you manage a non-perforated LBO?

A

Drip and suck: IV fluids, NG tube

Use a rigid or flexible sigmoidoscopy to straighten out

51
Q

How would you manage a perforated LBO?

A

Emergency surgery
Resect
Wash out peritoneum + bowel

52
Q

What is non-mechanical obstruction?

A

Failure of peristalsis
Adynamic bowel
No mechanical cause

53
Q

What are the clinical features of non-mechanical obstruction?

A

Pain free
Distention
Vomiting not projectile
Absent or tinkling bowel sounds

54
Q

How do you treat non-mechanical obstruction?

A 
Nil by mouth
IV fluids
Nasogastric aspiration
Treat the underlying cause
Supportive nutrition

Gastrointestinal (20 decks)

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