Bowel Obstruction

Question 1

What types of bowel obstructions are there ?

Answer 1

Small bowel obstruction (60-75%)
Large bowel obstruction

(mechanical obstruction)

Pseudo-obstruction
(non-mechnical obstruction)

Question 2

What are the causes of small bowel obstruction SBO

Answer 2

Intrabdominal Adhesions - band of intrabdominal scarring due to previous surgery/infection

strangulating hernias
malignancy
Crohns diseases

Question 3

Pathophysiology of small bowel obstruction

Answer 3

Blockage result increased pressure above the blockage:

> Causes Distension above the blockage
increased pressure pushes blood vessels within bowel wall > compressed vessels results in ischaemia, necrosis, perforation

Question 4

Clinical presentation of SBO

Answer 4

PAIN: initially COLICKY but then diffuse, higher in the abdomen than LBO, INTERMITTENT

First - Profuse VOMITING following pain (occurs earlier in SBO than LBO) - think SB IS CLOSER TO MOUTH

Then CONSTPATION

Increased bowel sounds (TINKLING)

Mild Abdominal distention

Question 5

Causes of large bowel obstruction

Answer 5

MALIGNANCY (90%) - more common in West

Volvulus (twisting of the bowel on its mesenteric axis, sigmoid colon most common place)
Diverticulitis
Crohn’s disease
Intussusception (telecscoping of bowel into eachother)

Question 6

Clinical presentation of LBO

Answer 6

THIS IS A MEDICAL EMEGENCY

Abdominal pain
-more CONSTANT & DIFFUSE than SBO
usually occurs lower in the abdomen (LIF)

-Much more ABDOMINAL DISTENTION than SBO

Palpable mass e.g. hernia

Question 7

DX - Bowel Obstruction

Answer 7

1st line: abdominal X-ray
- Dilated bowel loops proximal to obstruction

+ transluminal gas shadows proximal to obstruction (w/sbo no gas in large bowels )

LBO - coffe bean sign (appearance of volvulus)

GOLD STANDARD: non-contrast CT - localises the obstruction

Other - FOR LBO
DRE digital rectal exam:
empty rectum and hard compacted stool

Question 8

Clinical presentation of LBO

Answer 8

THIS IS A MEDICAL EMEGENCY

First constipation then +/- Vomiting

Hyperactive bowel sounds then eventually absent - no movement

Abdominal pain
-more CONSTANT & DIFFUSE than SBO
usually occurs lower in the abdomen (LIF)

-Much more ABDOMINAL DISTENTION than SBO

Palpable mass e.g. hernia

Question 9

Management of an obstructed bowel (SBO, LBO)

Answer 9

Aggressive fluid resuscitation

Decompression of the bowel “drip and suck”
NG tube- nasogastric tube
IV fluids to hydrate

Analgesia,
Anti-emetics (metoclopramide)

Antibiotics - stasis is the basis

Laparotomy - Surgery to remove obstruction

Question 10

Pseudo bowel obstructions

Answer 10

Present identically to SBO/LBO but underlying cause should be treated first

CAUSES:
Post operative state - opiate induced ileum paralysis
intra abdo sepsis
neural/vascular impairment
trauma