Intestinal Obstruction
Basics
DESCRIPTION
Pathologic blockage of progression of intestinal contents:
1.May be partial or complete
2.May arise from intrinsic abnormalities (e.g., meconium ileus or intestinal
atresia) or extrinsic
abnormalities (e.g., adhesions and volvulus).
•
Paralytic ileus: Failure of intestinal motor function without mechanical
obstruction:
1.Very common after abdominal operations.
2.Common causes:
•
Infection (pneumonia, gastroenteritis, peritonitis, systemic sepsis)
•
Drugs (i.e., opiates, loperamide, vincristine)
•
Metabolic abnormalities (hypokalemia, uremia, myxedema, and diabetic
ketoacidosis)
•
Chronic intestinal pseudo-obstruction: A severe intestinal motility disorder
described in diverse diseases including
muscular, endocrine, metabolic and autoimmune disorders. Examples include
Duchenne and diabetes mellitus.
EPIDEMIOLOGY
The different causes have their own identified epidemiologic patterns:
•
Postoperatve adhesions occur very often after all laparotomies
•
Small bowel obstruction secondary to
Ascaris lumbricoides
in tropical and subtropical countries
•
Colonic volvulus secondary to aerophagia and constipation in mentally
retarded children
•
Meconium ileus equivalent in children with cystic fibrosis
Incidence
Occurs in ~1 in 1,500 live births
BASICS-EPIDEMIOLOGY-Prevalence
Down syndrome (with a high prevalence, 20–30%, of duodenal atresia)
PATHOPHYSIOLOGY
•
Mechanical obstruction:
1.Intestinal contents accumulate proximal to the site of obstruction.
2.The bowel distends with swallowed air, ingested food, secretions, and gases
from intestinal reactions and
bacterial fermentation.
3.Retrograde flow of intestinal contents and reflex gut distention cause
vomiting.
4.Internal and external losses result in hypovolemia, oliguria, and azotemia.
5.Bacteria proliferate in the small bowel and its contents become feculent.