What are the symptoms of small bowel obstruction?

Symptoms of Small Bowel Obstruction

The classic symptoms of small bowel obstruction include colicky abdominal pain, nausea, vomiting, abdominal distension, and constipation or obstipation (inability to pass gas or stool). 1

Cardinal Symptoms

• Abdominal Pain

  • Typically crampy/colicky in nature (65% of cases) 2
  • Often located in the epigastrium (45%) or central abdomen 2, 1
  • Intermittent at first, becoming more constant as obstruction progresses
  • Pain may worsen after eating or with prokinetic medications 2

• Vomiting

  • More prominent and earlier in proximal obstructions 2
  • May be bilious (yellow/green) in proximal obstruction
  • Feculent vomiting suggests distal obstruction 2
  • Provides relief from pain temporarily

• Abdominal Distension

  • Progressive swelling of the abdomen
  • More pronounced in distal obstructions
  • May be less obvious in early or proximal obstructions

• Altered Bowel Habits

  • Constipation progressing to obstipation (inability to pass gas or stool)
  • When obstruction resolves, diarrhea may follow due to accumulated secretions 2

Associated Symptoms and Signs

• Abnormal Bowel Sounds

  • Initially high-pitched, hyperactive bowel sounds
  • Later may become absent as bowel function diminishes

• Tachycardia

  • Important warning sign, especially in postoperative patients 2
  • Considered the most sensitive sign associated with surgical complications after bariatric surgery 2

• Dehydration Signs

  • Due to vomiting, decreased intake, and third-spacing of fluids

Warning Signs of Complications

• Signs of Strangulation/Ischemia

  • Fever
  • Tachycardia
  • Constant, severe, non-colicky pain
  • Localized tenderness
  • Peritoneal signs (guarding, rigidity)
  • Hypotension (late sign)
  • Decreased urine output
  • Tachypnea with hypoxia 2

• Laboratory Abnormalities Suggesting Complications

  • Leukocytosis (elevated white blood cell count)
  • Elevated lactate levels
  • Metabolic acidosis

Variations in Presentation

1. Partial vs. Complete Obstruction

   • Partial: Intermittent symptoms, may still pass some gas/stool
   • Complete: More severe symptoms, absolute constipation

2. Proximal vs. Distal Obstruction

   • Proximal: Earlier and more prominent vomiting, less distension
   • Distal: More pronounced distension, later vomiting (may be feculent)

3. Closed-Loop Obstruction

   • Severe pain of sudden onset
   • Rapid progression to peritonitis
   • Higher risk of strangulation and perforation

4. Special Populations

   • Elderly: May have atypical presentations 1
   • Pregnant women: Symptoms may be confused with normal pregnancy complaints 2
   • Post-bariatric surgery: May present with unique symptoms requiring specialized evaluation 1

Important Clinical Pearls

• The classic peritoneal signs are often absent in patients with obesity due to body habitus 2
• Opioid use can mask symptoms and invalidate tests of small bowel motility 2
• Tachycardia should be taken as a serious warning sign of complications 2
• The combination of fever, tachycardia, and tachypnea is a significant predictor of anastomotic leak or other serious complications 2
• In patients with a history of abdominal surgery, adhesions are the most likely cause (85% sensitivity, 78% specificity) 2

Remember that early recognition of symptoms, particularly those suggesting complications like strangulation or ischemia, is crucial for timely intervention and improved outcomes.