Fecal impaction

Background

• Typically a complication of chronic constipation that results in the accumulation hardened fecal matter in the colon or rectum that cannot be spontaneously evacuated

Risk Factors

• Elderly and young age
• Chronic constipation
• Lifestyle factors (immobility, low fiber diet, dehydration)
• Medications that impair GI motility (anticholinergics, antipsychotics, opioids)
• Anatomic abnormalities (malignancy, anorectal disease, Hirschsprung)
• Neurologic conditions (dementia, spinal cord injury, cerebral palsy)

Clinical Features

History

• Abdominal pain or bloating
• Nausea and vomiting
• Obstipation
• Agitation/confusion (elderly patients with neuropsychiatric conditions)
• Urinary incontinence
• Overflow stool incontinence

Physical exam

• Abdominal distention and/or tenderness
• Palpable firm stool balls on digital rectal exam

Differential Diagnosis

• Constipation
• Colorectal malignancy
• Diverticulitis
• Bowel obstruction
• Stercoral colitis

Evaluation

Pelvic CT scan showing a large fecal impaction (arrow).

• Digital rectal exam
• Chemistry to evaluate for hypokalemia or hypercalcemia
• TSH if indicated
• Abdominal X-Ray to evaluate for air-fluid levels and free-air
• CT if severe presentation
  • Stercoral colitis is CT finding caused by impacted fecal material causing pressure edema and ischemia on the bowel wall. Left untreated, the condition can lead to wall ischemia, ulceration, and perforation.
    • Findings include colonic wall thickening, pericolonic fat stranding, and extraluminal bubbles of gas or abscess (signs of perforation); all of which are not found in uncomplicated fecal impaction.

Management

• Surgery if there are signs of perforation or peritonitis
• Distal impactions - manual disimpaction and/or rectal suppositories or enemas
• Proximal impactions typically respond better to oral laxatives
• After initial disimpaction, address risk factors and initiate a maintenance bowel regimen

Disposition

• Consider admission for patient's with stercoral colitis for aggressive bowel regimen and washout

See Also

• Constipation