Bowel Obstruction Flashcards
Bowel obstruction
Occurs when intestinal contents cannot pass through
the GI tract
Obstruction may be partial or complete
Causes classified as mechanical or non-mechanical
Mechanical Bowel Obstruction
Accounts for 90% of all bowel obstructions
Affects the lumen of the bowel
Caused by an occlusion of the lumen of bowel
Most occur in the small intestine
Mainly caused by adhesions (50%), hernias(15%)
or neoplasms(15%)
Carcinoma is the most common cause of large
bowel obstruction
Obstruction Non – Mechanical Bowel
May result from a neuro-muscular or vascular disorder
Related to peristalsis
Paralytic ileus (lack of intestinal peristalsis) is the most
common
Occurs after surgery
Can be caused by inflammatory response eg. appendicitis
Electrolyte abnormalities
Spinal fractures
Vascular obstructions
Due to interference to blood supply to a portion of intestines
Pathophysiology of Bowel Obstruction
Normally 6-8L of fluid enters small bowel
daily
Approx 75% of intestinal gas is swallowed air
Bacterial metabolism produces methane &
hydrogen gases
Fluid, gas & intestinal contents accumulate
proximal to the intestinal obstruction
This causes distension, reduces the absorption
of fluids & stimulates intestinal secretions
Pathophysiology - continued
The increase in fluid increases the pressure in the
lumen of the bowel
Increased pressure leads to increase in capillary
permeability & extravasation of fluids &
electrolytes into the peritoneal cavity
Oedema, congestion & necrosis from impaired
blood supply can occur
Retention of fluid in the intestine & peritoneal
cavity can lead to severe hypovolaemia & shock
Bowel Obstruction - Signs & Symptoms/Manifestations
Vary depending on the location of the obstruction
Nausea/Vomiting
Abdominal pain
Small bowel: colicky, cramp-like & intermittent
Large bowel: low grade cramp
Abdominal distension (greater in large bowel)
Bowel Sounds
Rapid, high-pitched tinkling
Absent
Inability to pass flatus
Constipation
