What are the key physical exam findings in a patient with suspected Small Bowel Obstruction (SBO)?

Key Physical Examination Findings in Small Bowel Obstruction (SBO)

The most important physical examination findings in suspected small bowel obstruction include abdominal distension, abnormal bowel sounds (either absent or high-pitched), and tenderness to palpation, with abdominal distension having the highest positive likelihood ratio of 16.8 for intestinal obstruction. 1

Cardinal Physical Examination Findings

High-Yield Findings

• Abdominal distension: Most reliable physical finding with highest predictive value 2, 1
• Abnormal bowel sounds: Either high-pitched/tinkling or absent 2
• Abdominal tenderness: Often diffuse or periumbilical 2
• Vomiting: Typically bilious in more established obstruction 2

Signs of Peritonitis/Strangulation (Surgical Emergency)

• Severe direct tenderness with involuntary guarding 3
• Abdominal rigidity 3
• Rebound tenderness: Highly concerning for peritonitis 2
• Fever: May indicate strangulation or perforation 2
• Tachycardia: Often present with dehydration or developing sepsis 3

Examination Algorithm

1. Initial Observation:

   • Assess overall appearance: Restlessness and signs of acute illness 3
   • Check vital signs: Tachycardia, hypotension, and fever suggest complications 2, 1
   • Observe for dehydration: Dry mucous membranes, decreased skin turgor 3

2. Abdominal Examination:

   • Inspection: Look for distension, visible peristalsis, surgical scars (suggesting adhesions) 2
   • Auscultation: Listen for high-pitched, tinkling bowel sounds (early obstruction) or absent sounds (late/complete obstruction) 2
   • Percussion: Tympany over distended loops 4
   • Palpation: Assess for tenderness, guarding, rigidity, and rebound tenderness 2

3. Hernia Examination:

   • Thoroughly examine all potential hernia sites (inguinal, femoral, umbilical, incisional) 2
   • Check for Howship-Romberg sign (pain along medial thigh with internal rotation) which may indicate obturator hernia 5

4. Rectal Examination:

   • Assess for masses, impaction, or blood 3

Special Considerations

Distinguishing Partial vs. Complete Obstruction

• Partial obstruction may present with watery diarrhea (can be mistaken for gastroenteritis) 2
• Complete obstruction typically presents with obstipation 3

Elderly Patients

• Pain may be less prominent in elderly patients 2
• Higher risk of atypical presentation 2

Limitations of Physical Examination

• Physical examination alone has limited sensitivity (approximately 48%) for detecting strangulation, even in experienced hands 2
• Laboratory tests and imaging are necessary complements to physical examination 2
• The absence of peritoneal signs does not exclude bowel ischemia 2

Red Flags Requiring Immediate Surgical Consultation

• Signs of peritonitis (rigid abdomen, rebound tenderness) 2
• Hemodynamic instability with abdominal findings 1
• Severe, unremitting pain despite adequate analgesia 3
• Fever with abdominal findings 2

Physical examination findings must be correlated with laboratory values (leukocytosis, elevated lactate) and imaging studies (preferably CT with IV contrast) for accurate diagnosis and management of SBO, as physical examination alone cannot reliably detect complications such as strangulation or ischemia 2, 1.