What are the causes of Small Bowel Obstruction (SBO)?

From the Guidelines

Small bowel obstruction (SBO) is primarily caused by adhesions, which account for approximately 60-75% of cases, as reported in the most recent study 1. The etiology of SBO can be multifactorial, and understanding the causes is essential for appropriate diagnosis and management.

Common Causes of SBO

• Adhesions from previous abdominal surgeries, which form as scar tissue develops during the healing process, creating bands that can entrap loops of bowel 1
• Hernias, including inguinal, femoral, umbilical, and incisional hernias, where portions of the intestine protrude through weakened areas of the abdominal wall 1
• Malignancies, which can cause SBO through direct tumor invasion or metastatic disease compressing the bowel lumen 1
• Inflammatory bowel disease, particularly Crohn's disease, which can lead to SBO due to stricture formation from chronic inflammation 1

Less Common Causes of SBO

• Foreign bodies, gallstone ileus, intussusception, volvulus, and congenital abnormalities like intestinal atresia or malrotation 1
• Rare causes, including radiation enteritis, bezoars, and strictures from NSAIDs or other medications 1 The most recent study 1 suggests that adhesions are also a common cause of SBO in patients with a virgin abdomen, accounting for 47.9% of cases. This highlights the importance of considering adhesions as a potential cause of SBO, even in patients without a history of abdominal surgery.

Clinical Implications

Understanding the causes of SBO is crucial for guiding diagnosis and management, which often requires a combination of supportive care, nasogastric decompression, and potentially surgical intervention depending on the underlying etiology 1.

From the Research

Causes of Small Bowel Obstruction (SBO)

• The most common causes of SBO are intrabdominal adhesions and intestinal hernias, as stated in 2.
• Other causes of SBO include small bowel diseases, such as fibrostenotic Crohn's strictures and NSAID diaphragm disease, as mentioned in 2.
• Adhesions are responsible for approximately 65% of SBO cases, while hernias account for around 10% of cases, as reported in 3.
• Neoplasms, Crohn's disease, and other conditions also contribute to SBO, with each accounting for around 5% of cases, as stated in 3.

Diagnosis and Treatment of SBO

• Computed tomography (CT) and magnetic resonance (MR) enterography are useful diagnostic tools for identifying the causes of SBO, as mentioned in 2.
• Conservative management is often successful in treating SBO, especially in cases without strangulation or bowel ischemia, as reported in 4.
• Surgery may be necessary in cases where conservative management fails or when there are signs of bowel compromise, as stated in 4, 3, 5.
• Laparoscopic adhesiolysis is a recommended surgical approach for treating adhesive SBO, as mentioned in 5.

Clinical Presentation of SBO

• The classical clinical tetrad of SBO includes abdominal pain, nausea and emesis, abdominal distention, and constipation-to-obstipation, as reported in 3.
• Physical examination may reveal signs of dehydration, sepsis, and abdominal tenderness, as stated in 3.
• Severe direct tenderness, involuntary guarding, abdominal rigidity, and rebound tenderness suggest advanced SBO, as mentioned in 3.