Differential Diagnoses for Increased Bowel Sounds

Mechanical Bowel Obstruction

The American College of Surgeons recommends immediate evaluation for mechanical bowel obstruction, as it can progress to bowel ischemia with mortality rates up to 25% if untreated 1
Mechanical bowel obstruction is characterized by colicky abdominal pain that worsens with attempts to overcome the obstruction, and is often accompanied by rushes of high-pitched bowel sounds and absence of flatus and bowel movements 1
The presence of abdominal distension with visible peristalsis in thin patients is a strong indicator of mechanical bowel obstruction, occurring in 65.3% of cases 1, 2
Small bowel obstruction is more commonly caused by adhesions (55-75% of cases), while large bowel obstruction is more commonly caused by cancer (60% of cases) 1
Warning signs of strangulation or ischemia include fever, tachycardia, tachypnea, confusion, intense pain unresponsive to analgesics, and transition from hyperactive to absent bowel sounds 1

The American Gastroenterological Association notes that gastroenteritis is characterized by increased bowel sounds with watery diarrhea, nausea, and vomiting, and typically has a self-limited course with recent dietary exposure or sick contacts 1, 2
Crampy abdominal pain that is relieved by bowel movements is a key distinguishing feature of gastroenteritis, unlike mechanical bowel obstruction 1

The Rome Foundation recommends that IBS be diagnosed based on recurrent abdominal pain relieved by defecation, looser and more frequent stools with onset of pain, and symptoms present for more than 6 months with intermittent flares 3, 4
Normal physical examination between episodes and absence of alarm features (weight loss, rectal bleeding, nocturnal symptoms, anemia) are supportive features of IBS 3

The American College of Gastroenterology recommends that early intestinal ischemia be suspected in patients with intense abdominal pain out of proportion to physical findings, and initially hyperactive bowel sounds that progress to absent sounds as ischemia worsens 1
Risk factors for early intestinal ischemia include atrial fibrillation, recent myocardial infarction, and peripheral vascular disease 5

The American College of Emergency Physicians recommends a step-wise approach to diagnosis, including assessment for surgical emergency, characterization of bowel sound pattern, correlation with stool pattern, and targeted history and physical examination 1
Laboratory tests, such as lactate level and complete blood count, and imaging studies, such as CT abdomen/pelvis with IV contrast, are essential for diagnosis and management 1, 2
The American College of Radiology recommends that CT abdomen/pelvis with IV contrast be used as the gold standard for diagnosis of mechanical bowel obstruction, with an accuracy of over 90% 1