What is the most common cause of small bowel obstruction during pregnancy?

Most Common Cause of Small Bowel Obstruction During Pregnancy

The most common cause of small bowel obstruction during pregnancy is adhesions, accounting for approximately 50% of cases. 1

Etiology of Small Bowel Obstruction in Pregnancy

• Adhesions are the predominant cause (approximately 50% of cases), most commonly from previous abdominal operations 1
• Other less common causes include:
  • Intestinal volvulus (24% of cases) 2
  • Intussusception (5% of cases) 2
  • Incarcerated hernias 1
  • Malignancy (4-13% of cases) 1
  • Gallstone ileus 1

Clinical Significance and Outcomes

• Small bowel obstruction during pregnancy is rare but represents a significant clinical challenge with high risks 1
• The failure rate of non-operative treatment in pregnant patients with adhesive small bowel obstruction is remarkably high (94%) 1
• Risk of fetal loss is approximately 17% and maternal mortality is around 2% 1, 3
• In cases of adhesional SBO during pregnancy, 91% require surgical management with a 14% fetal loss rate 3

Diagnostic Approach

• Imaging studies used to diagnose SBO in pregnancy include:
  • Ultrasound (83% of cases) 1
  • MRI (33% of cases) - preferred method due to absence of radiation 1, 4
  • Abdominal X-ray (33% of cases) - used with caution due to radiation concerns 1
  • CT scan (25% of cases) - typically avoided due to radiation exposure 1

Management Considerations

• Urgent MRI of the abdomen is recommended to diagnose the etiology of SBO in pregnancy 3
• For adhesional SBO, conservative treatment may be initiated with a low threshold for laparotomy 3
• For other causes such as volvulus or internal hernia, surgical intervention remains the treatment of choice 3
• The median time from admission to laparotomy in pregnant patients with SBO is approximately 48 hours 2
• Bowel strangulation requiring resection occurs in 23% of pregnant patients with SBO 2

Clinical Pitfalls and Caveats

• Symptoms of SBO in pregnancy may overlap with normal pregnancy complaints, leading to delayed diagnosis 5
• Common symptoms include abdominal pain (98%), vomiting (82%), and constipation (30%) 5, 2
• Abdominal tenderness on palpation is found in 71% and abnormal peristalsis in 55% of cases 5
• The risk of intestinal torsion is higher at 16-20 and 32-36 weeks of pregnancy and during puerperium 5
• Maternal and fetal outcomes worsen with delayed diagnosis and intervention 3, 2

Therefore, based on the most recent and highest quality evidence from the World Journal of Emergency Surgery guidelines, the correct answer is (b) adhesions.