Bowel obstruction syndrome !

Syndrome

Bowel contents cannot move forward: colicky pain, vomiting, a swollen belly and no passing of gas or stool.

Updated 2026-11-01

See it in 3D: Jejunum · Ileum · Cecum · Ascending colon · Transverse colon · Sigmoid colon

What it is

Bowel obstruction is the arrest of intestinal transit, from a mechanical cause (something closes the lumen) or a functional one (paralytic ileus, with no physical block). It is recognized by four findings: colicky pain, vomiting, distension and failure to pass gas and stool. The urgent bedside task is spotting strangulation, because ischemic bowel can perforate.

Key findings

Inspection: distension, scars, visible hernias and sometimes visible peristalsis in thin patients.
Auscultation: increased, high-pitched sounds early; silence late or in ileus.
Percussion: diffuse tympany.
Palpation: diffuse tenderness; localized tenderness with guarding or rebound suggests compromised bowel.
Signs of dehydration: dry mucosa, tachycardia, oliguria.
Rectal exam: empty rectum, mass or fecal impaction.

Pathophysiology

Above the block the bowel dilates with swallowed air and with digestive secretions that are not reabsorbed.
Peristalsis increases to push past the block: this causes the colicky pain and the 'fighting' bowel sounds.
Fluid is sequestered in the lumen and bowel wall (third space) and lost by vomiting: dehydration, oliguria and electrolyte disturbances follow.
As wall pressure rises, venous return fails first and then arterial inflow: ischemia leads to necrosis, bacterial translocation and perforation.
In paralytic ileus there is no block: peristalsis stops because of recent surgery, peritonitis, electrolyte disturbances or drugs.

Common causes

Small bowel: postoperative adhesions, inguinal, femoral, umbilical or incisional hernias, tumors and inflammatory bowel disease.
Colon: colorectal cancer, sigmoid volvulus, diverticular stricture and fecal impaction in older adults.
Children: intussusception, malformations and hernias.
Paralytic ileus: after surgery, peritonitis, hypokalemia and drugs such as opioids.

Tests that confirm it

Abdominal X-ray: dilated loops and air-fluid levels.
Contrast CT: confirms the site, the cause and signs of ischemia.
Electrolytes, renal function and lactate to gauge the impact.

Test yourself

Think of the answer, then tap the question to see it.

What are the four cardinal findings of bowel obstruction?

Colicky abdominal pain, vomiting, abdominal distension and failure to pass gas and stool.

How do bowel sounds change during a mechanical obstruction?

Early on they are increased and high-pitched from fighting peristalsis; with time, bowel fatigue or ischemia makes them sparse or absent.

Which findings suggest that an obstruction has strangulated?

Pain that changes from colicky to constant, fever, tachycardia, localized tenderness with guarding or rebound, and a worsening general state.

Why does a patient with bowel obstruction become dehydrated even without diarrhea?

Fluid pools in the lumen and wall of the dilated bowel (third space) and is lost by vomiting, so circulating volume falls.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Bowel Obstruction | Intestinal Obstruction | MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026); Abdominal Pain | MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026).

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Representative model, for educational purposes only.