Background: This study analysed the risk of surgically treated small bowel obstruction after open appendicectomy.
Methods: This was a historical cohort study of 245 400 patients who underwent open appendicectomy and population-based matched controls, identified by linkage of computer registries. Analyses were made with the life-table technique, Kaplan-Meier plots and Cox proportional hazards regression analysis.
Results: The cumulated risk of surgically treated small bowel obstruction after appendicectomy was 0.41 per cent after 4 weeks, 0.63 per cent after 1 year and 1.30 per cent after 30 years of follow-up, compared with 0.003 per cent at 1 year and 0.21 per cent after 30 years of follow-up among the non-operated controls. The highest risk was found after operation for other diagnoses (adjusted hazard ratio 5.2 (95 per cent confidence interval 4.6-5.8)), followed by operation for perforated appendicitis (adjusted hazard ratio 3.5 (3.1-3.8)), non-specific abdominal pain (adjusted hazard ratio 2.6 (2.3-3.0)) and mesenteric lymphadenitis (adjusted hazard ratio 2.4 (2.0-2.8)) compared with operation for non-perforated appendicitis. The relation with age was J shaped, with the lowest risk at 20-39 years. Women had a slightly lower risk than men.
Conclusion: The risk of postoperative small bowel obstruction needing surgical treatment after open appendicectomy is lower than previously thought. Perforated appendicitis, negative appendicectomy and high age are the risk factors.