The clinical significance of adhesions: focus on intestinal obstruction

Postoperative adhesions occur after almost every abdominal surgery and are the leading cause of intestinal obstruction, accounting for more than 40% of all cases and 60% to 70% of those involving the small bowel. This contrasts with earlier experience in the Western World and current practice in the Third World, where abdominal operations are infrequent, hernias remain untreated, and strangulated hernia is common. These are among the findings of prospective and retrospective studies on adhesions conducted at the Westminster Medical School, University of London, London, UK, and of other published studies on the clinical consequences of postoperative intra-abdominal adhesions and resultant intestinal obstruction. In an analysis of 210 patients who had undergone at least one previous abdominal operation, 92.9% had postsurgical adhesions. This is not surprising, given the extreme delicacy of the peritoneum and the fact that apposition of two injured surfaces nearly always results in adhesion formation. Problems resulting from postsurgical adhesions create a considerable workload. At Westminster Hospital over 24 years, intestinal obstruction accounted for 0.9% of all admissions, 3.3% of major laparotomies and 28.8% of cases of large or small bowel obstructions. A 1992 British survey reported an annual total of 12,000 to 14,400 cases of adhesive intestinal obstruction. In 1988 in the United States, admissions for adhesiolysis accounted for nearly 950,000 days of inpatient care. Risk factors, such as type of surgery and site of adhesions, as well as timing and recurrence rate of adhesive obstruction, remain unpredictable or poorly understood. The type of surgery most frequently leading to adhesive obstruction includes colonic, and especially rectal surgery, appendicectomy, and gynecological procedures. Laparoscopy does not seem to eliminate the risk of adhesions and adhesive obstruction. Adhesions involving the small intestine occur less frequently than those involving the omentum, but are more likely to become obstructive. Follow-up of over 2,000 laparotomies at the Westminster Hospital demonstrated that 1% of patients developed adhesive obstruction within one year of surgery, and half of these occurred within the first postoperative month. However, obstruction may occur at any time, and some 20% of cases appeared more than 10 years later. Recurrent obstruction following adhesiolysis is common, but actuarial tables still need to be constructed. Adhesive obstruction is clinically challenging, since there is no simple way to differentiate between adhesive and strangulated obstructions. Mortality rates escalate from 3% for simple obstructions to 30% when the bowel becomes necrotic or perforated.