What are the symptoms of bowel obstruction?

Symptoms of Bowel Obstruction

The cardinal symptoms of bowel obstruction are absence of passage of flatus (90% of cases), absence of bowel movements (80.6%), abdominal distension (65.3%), colicky abdominal pain, nausea, and vomiting. 1, 2

Core Clinical Presentation

The classic symptom complex includes:

• Absence of flatus passage occurs in 90% of patients and is one of the most reliable indicators 1, 2
• Absence of bowel movements is present in 80.6% of cases 1, 2
• Abdominal distension occurs in 65.3% of patients and has a strong predictive value with a positive likelihood ratio of 16.8 1, 2
• Colicky abdominal pain that worsens as the bowel attempts to overcome the obstruction 1
• Nausea and vomiting are universal symptoms, though their timing and severity differ by location 1
• Abdominal bloating is commonly reported 1

Physical Examination Findings

Key signs to identify on examination:

• Abdominal tenderness is frequently present 1
• Hyperactive or absent bowel sounds depending on the stage of obstruction 1
• Visible peristalsis may be observed in thin patients 1
• Digital rectal examination may reveal blood or a rectal mass, particularly in colorectal cancer cases 1

Distinguishing Small vs. Large Bowel Obstruction

Small bowel obstruction presents with:

• More frequent and earlier vomiting that occurs sooner in the clinical course 1
• Green/yellow vomit in proximal obstructions 1
• More acute symptom onset 1

Large bowel obstruction presents with:

• Less frequent vomiting that occurs later 1
• Feculent vomiting in distal obstructions 1
• More gradual symptom development 1
• Recurrent left lower quadrant pain may be present 1
• History of bloody stools may precede obstruction 1

Critical Warning Signs Requiring Urgent Intervention

These symptoms indicate potential strangulation, ischemia, or perforation and demand immediate surgical evaluation:

• Fever, tachypnea, tachycardia, and confusion suggest bowel ischemia 1
• Intense pain unresponsive to analgesics indicates possible strangulation 1
• Diffuse abdominal tenderness, guarding, or rebound tenderness signal peritonitis 1
• Absent bowel sounds suggest advanced ischemia 1
• Signs of shock including hypotension, cool extremities, mottled skin, and oliguria 1

Laboratory Abnormalities Suggesting Complications

• Leukocytosis and neutrophilia indicate inflammatory complications 1
• Elevated lactic acid levels suggest bowel ischemia 1
• Low serum bicarbonate and arterial pH indicate metabolic acidosis from ischemia 1
• Elevated amylase levels may be present 1
• Abnormal renal function tests reflect dehydration 1

Common Diagnostic Pitfalls to Avoid

Critical errors that delay diagnosis:

• Mistaking incomplete obstruction with watery diarrhea for gastroenteritis is a dangerous misdiagnosis, as paradoxical diarrhea can occur with partial obstruction 1, 3
• Overlooking bowel obstruction in elderly patients where pain presentation may be atypical or less prominent 1, 3
• Failing to examine all hernia orifices and previous surgical incision sites during physical examination 3

Essential Historical Information

Ask specifically about:

• Previous abdominal surgeries (85% sensitivity for adhesive small bowel obstruction) 1, 3
• Previous diverticulitis episodes or chronic constipation suggesting diverticular stenosis or volvulus 1, 3
• Rectal bleeding or unexplained weight loss suggesting colorectal cancer 1, 3
• Timing of last defecation and flatus passage 3
• Medications affecting peristalsis that could cause pseudo-obstruction 3