What are the symptoms of bowel blockage?

Symptoms of Bowel Obstruction

Bowel obstruction presents with colicky abdominal pain, absence of flatus (90% of cases), absence of bowel movements (80.6% of cases), nausea and vomiting, and abdominal distension (65.3% of cases). 1

Core Clinical Features

The hallmark symptoms include:

• Colicky abdominal pain that worsens as the bowel attempts to overcome the obstruction 1
• Absence of passing gas (flatus) occurs in 90% of cases 1
• Absence of bowel movements occurs in 80.6% of cases 1
• Nausea and vomiting are prominent, particularly in small bowel obstruction where they occur earlier and more frequently 1
• Abdominal bloating and distension occurs in 65.3% of cases and is a strong predictive sign 1
• Abdominal tenderness on physical examination 1

Physical Examination Findings

Key signs to identify include:

• Hyperactive or absent bowel sounds depending on the stage of obstruction 1
• Visible peristalsis may be seen in thin patients 1
• Abdominal distension is a strong predictive finding with a positive likelihood ratio of 16.8 1
• Digital rectal examination may reveal blood or a rectal mass if colorectal cancer is the cause 1

Critical Warning Signs Requiring Emergency Evaluation

Complete intestinal obstruction with severe abdominal pain requires emergency surgical assessment. 2 Watch for these red flags indicating strangulation, ischemia, or perforation:

• Fever, rapid breathing (tachypnea), rapid heart rate (tachycardia), and confusion 1
• Intense pain unresponsive to pain medications 1
• Diffuse abdominal tenderness, guarding, or rebound tenderness indicating peritonitis 1
• Absent bowel sounds (as opposed to hyperactive sounds in early obstruction) 1
• Signs of shock: hypotension, cool extremities, mottled skin, and decreased urine output 1
• Regular vomiting or absolute constipation with distended abdomen indicates complete obstruction 2

Distinguishing Small vs. Large Bowel Obstruction

Small bowel obstruction:

• More frequent vomiting that occurs earlier in the disease course 1
• Green/yellow vomit suggests proximal small bowel obstruction 1
• Most commonly caused by adhesions (55-75% of cases), especially with prior abdominal surgery 1

Large bowel obstruction:

• Less frequent vomiting with more gradual symptom development 1
• Feculent (foul-smelling) vomiting suggests distal large bowel obstruction 1
• Recurrent left lower quadrant pain may be present 1
• Most commonly caused by cancer (60% of cases) 1
• History of bloody stools may be a presenting symptom 1

Laboratory Findings Suggesting Complications

When obstruction progresses to ischemia or perforation:

• Elevated white blood cell count (leukocytosis) and increased neutrophils 1
• Elevated lactic acid levels indicating tissue ischemia 1
• Low serum bicarbonate and arterial blood pH suggesting metabolic acidosis 1
• Elevated amylase levels 1
• Abnormal kidney function tests indicating dehydration 1

Important Clinical Pitfalls

Faecal impaction can cause overflow diarrhea that mimics gastroenteritis - this should be considered as a possible cause of apparent diarrhea, especially in patients on constipating medications. 2 Digital rectal examination can identify fecal impaction in 80% of cases. 3

Incomplete bowel obstruction may cause intermittent symptoms that resolve temporarily, leading to delayed diagnosis. 2 Patients may experience relief when sticking to liquid diets, which can mask the underlying problem. 2

Pain after eating is characteristic - colicky pain is worse after oral intake because the bowel attempts to push contents past the obstruction. 2