Skip to Main Content


Proximal Obstruction


  • • Vomiting

    • Abdominal discomfort

    • Abnormal PO contrast x-rays


Mid or Distal Obstruction


  • • Colicky abdominal pain

    • Vomiting

    • Abdominal distention

    • Constipation-obstipation

    • Peristaltic rushes

    • Dilated small bowel on x-ray




  • • The most common surgical disorder of the small intestine

    • Common causes of obstruction:

    • -Adhesions: The most common cause of mechanical small bowel obstruction

      -Neoplasms: Intrinsic or extrinsic

      -Hernia: Due to incarceration of bowel

      -Intussusception: Common in children

      -Volvulus: Often results from congenital anomalies or acquired adhesions

      -Foreign bodies: Luminal blockage

      -Gallstone ileus: Passage of a large gallstone through a cholecystenteric fistula

      -Inflammatory bowel disease: Lumen is

      narrowed by inflammation or fibrosis

      -Stricture-luminal narrowing

      -Cystic fibrosis: Partial obstruction of the distal ileum and right colon


      -Paralytic ileus: Neurogenic


Symptoms and Signs


  • • Vomiting

    • Cramping abdominal pain

    • Obstipation

    • Distention

    • -Minimal in proximal obstruction

      -Pronounced in distal obstruction

    • Mild abdominal tenderness

    • Audible rushes and high-pitched tinkles


Strangulation Obstruction


  • • Shock

    • High fever

    • Abdominal pain: Severe and continuous

    • Vomitus may contain blood

    • Abdominal tenderness and rigidity


Laboratory Findings


  • • Hemoconcentration

    • Leukocytosis

    • Electrolyte abnormalities that depend on the level of obstruction and the severity of dehydration

    • Serum amylase is often elevated


Strangulation Obstruction


  • • Marked leukocytosis not accounted for by hemoconcentration

    • Metabolic acidosis


Imaging Findings


  • Abdominal x-ray

    • -Dilated bowel

      -Air-fluid levels (minimal in early, proximal, or closed loop obstruction)

    • The colon is often devoid of gas

    • Intraperitoneal air indicates perforation

    Contrast upper GI series: Assesses completeness of obstruction

    CT scan

    • -Intraperitoneal free fluid

      -Dilated bowel proximal and decompressed distal to the obstruction

      -Point of obstruction may be visualized

    • Gas within the bowel wall or portal vein may be seen in strangulation

    • Intraperitoneal free air or air-fluid levels indicate perforation


  • • Classification of small bowel obstruction

    • Functional (failure of peristalsis to propel intestinal contents) or mechanical (a physical barrier impedes aboral progress of intestinal contents)

    • Complete or partial

    • Simple (occludes the lumen only) or strangulated (impaired the blood supply leading to necrosis of the intestine)

    • Open loop (the lumen is occluded in 1 place) or closed loop (the lumen is occluded in at least 2 places)

    • 33% of strangulation obstructions are unsuspected before operation


Rule Out


  • • Acute appendicitis

    • Obstruction of the large intestine

    • Acute gastroenteritis

    • Acute pancreatitis

    • Mesenteric vascular occlusion

    • Pseudo-obstruction associated with scleroderma, systemic lupus erythematosus, amyloidosis, drug abuse, or radiation

    • Intrinsic dysmotility


  • • Abdominal x-ray

    • CBC

    • Serum electrolytes

    • ABG measurements (if strangulation suspected)

    • Serum lactate

    • Serum amylase and ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessSurgery Full Site: One-Year Subscription

Connect to the full suite of AccessSurgery content and resources including more than 160 instructional videos, 16,000+ high-quality images, interactive board review, 20+ textbooks, and more.

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessSurgery

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.