Adhesions develop in most patients following major abdominal surgery. During and after surgery, the balance between fibrin formation and fibrinolysis within the peritoneal cavity appears to be an important determinant of adhesion formation. The great majority of small-bowel obstructions are due to adhesions, whereas the great majority of colonic obstructions are due to tumors. Approximately 80% of adhesions develop postoperatively, 15% follow peritonitis, and 5% are attributed to congenital pathologies, post-traumatic causes, or remain of unknown etiology.
Adhesions occur in more than 90% of patients after major abdominal surgery. To date, there is still no safe and effective prophylaxis that completely prevents adhesion formation. In the development of intra-abdominal adhesions, injury to peritoneal surfaces, ischemic areas, intestinal fistulas, infection, and foreign materials (such as sutures and powder) play important roles. One of the most important factors in adhesion formation is ischemia. Experimental studies have shown that when ischemia is absent, adhesions either do not develop or develop at a low rate. Moreover, it has been demonstrated that adhesions can develop when ischemia occurs in an otherwise intact mesothelial layer. Local fibrinolytic activity is increased in non-ischemic regions and decreased in ischemic regions. While multiple factors play a role in the etiology of small-bowel obstruction, intra-abdominal adhesions related to prior surgeries are responsible in about 75% of cases.
Post-inflammatory adhesions account for 20–30% of all adhesive (band) obstructions. They may develop after non-operative treatment of appendicitis, diverticulitis, pelvic inflammatory disease, and cholecystitis attacks. In statistical analyses of postoperative adhesions, appendectomy almost always ranks among the leading prior operations. In one study, among small-bowel obstructions due to adhesions, 24% followed colorectal surgery, 22% gynecologic surgery, 15% herniorrhaphy (hernia repair), and 14% appendectomy.
Although laparoscopic techniques and minimally invasive surgery have been adopted to reduce intraoperative trauma, surgical technique alone is not sufficient to reduce postoperative adhesions and related complications.Future strategies to prevent adhesions should aim to control the cellular mediators in peritoneal fluid at the onset of the adhesion-formation process.Radiologically, the presence of air–fluid levels on an upright plain abdominal X-ray is an important finding. The leukocyte count may rise to 15,000–20,000/mm³; values above this range should raise suspicion of strangulation or mesenteric vascular diseases.
The frequency and significance of postoperative adhesions have been better appreciated with the increase in re-laparotomies. During re-laparotomies, adhesions make entry into the abdomen difficult, may lead to hard-to-control bleeding, distort anatomical structures, and consequently prolong operative time. All of these are associated with increased mortality and morbidity. It should be remembered that distended bowel segments are prone to injury. In some series, multiple adhesions have been shown to be the most common cause of small-bowel fistulas due to injuries occurring during laparotomy.
Among patients operated on for adhesive ileus, small-bowel perforation occurs in 34.6%, and colonic perforation in 2.5%. Obstruction due to adhesions may present in one-third of patients within the first year after the initial operation, and in the remainder at any time over a long period—even up to 20 years later. Recurrent obstruction develops subsequently in 5–21% of patients who have had adhesion-related intestinal obstruction. The clinical picture of adhesive ileus may occur on average 16.2 months after surgery.
1) According to the passage, the great majority of colonic obstructions are due to _____.
A) adhesions
B) tumors
C) hernias
D) gallstones
E) volvulus
2) Which statement is TRUE according to the passage?
A) There is a safe and fully effective prophylaxis that prevents adhesions.
B) Adhesions develop in fewer than half of patients after major abdominal surgery.
C) Ischemia is a key factor in adhesion formation, and local fibrinolytic activity decreases in ischemic regions.
D) Most small-bowel obstructions are caused by tumors rather than adhesions.
E) When ischemia is absent, adhesions can never develop.
3) Which finding should raise suspicion of strangulation or mesenteric vascular disease?
A) Upright abdominal X-ray showing air–fluid levels
B) Leukocyte count of 12,000/mm³
C) Leukocyte count above 20,000/mm³
D) Prior appendectomy
E) Adhesions presenting more than one year after surgery
4) Which of the following best reflects the passage regarding timing and recurrence of adhesion-related obstruction?
A) It occurs only within the first year and rarely recurs.
B) It usually appears after 20 years and never recurs.
C) It may occur within the first year in about one-third of patients, may appear at any time up to 20 years in others, and recurs in 5–21% of cases.
D) It always appears within six months and recurs in more than half of patients.
E) It appears on average 10 years after surgery and almost never recurs.
Answer Key
- B
- C
- C
- C