Postoperative adhesion is encountered in most cases after abdominal surgery. Adhesion may cause infertility, abdominal pain, or bowel obstruction. It may also be associated with difficulty entering the abdominal cavity and challenging dissection at future abdominal surgery. The most serious complication of intraabdominal adhesions is bowel obstruction. In a retrospective cohort study, half of bowel obstructions were related to open pelvic surgery.1 Myomectomy is also considered as a major cause of postoperative adhesions, especially when a posterior uterine incision is made.2
To minimize adhesion formation, the use of adhesion-reducing substances has been advocated. There have been many studies demonstrating their efficacy. However, the number of participants in most studies was relatively low.3 The purpose of our study was to evaluate the use of adhesion barrier in myomectomy or hysterectomy and the complications in the immediate postoperative period.
MATERIALS AND METHODS
We performed a retrospective cohort study using the data from The Healthcare Cost and Utilization Project Nationwide Inpatient Sample database of 2003–2011. The database includes hospital inpatient stays submitted by hospitals throughout the United States. Each year contains data for more than 7 million inpatient stays, including patient characteristics, diagnoses, and procedures. It is the largest U.S. inpatient database. The data are representative of approximately 20% of admissions to U.S. hospitals. As a review of a publicly available database, the study was exempted from review by our research and ethics board.
Our cohort included all patients between 2003 and 2011 with a primary discharge diagnosis of uterine myoma based on the International Classification of Diseases, 9th Revision, Clinical Modification (codes 218, 218.0, 218.1, 218.2, 218.9). Patients who underwent myomectomy or hysterectomy were identified using International Classification of Diseases, 9th Revision procedure codes: myomectomy (68.29) or hysterectomy (68.3, 68.4, 68.41, 68.9). Concomitant procedure codes were used to identify laparotomy (54.1), laparoscopy surgery (54.21, 68.51, 68.31, 65.01, 65.31, 65.41, 65.53, 65.63, 65.64), or robotic-assisted surgery (17.4, 17.42). The procedure code for the use of adhesion barrier (99.77) was introduced in October 2002.
As a result of the relationship between race and uterine myoma, we analyzed data for Caucasian, African American, Hispanic, or others. Insurance status categories were: private insurance, Medicare, Medicaid, or others. Different hospital locations were recorded: rural, urban nonteaching, and urban teaching. Comorbidities were assessed using the modified Deyo index.4
The outcomes included the use rate and perioperative complications associated with the use of adhesion barriers. The primary outcomes were ileus (560.1, 536.2) and small bowel obstruction (560.81, 560.9, 537.3). The secondary outcomes were fever (780.6), abscess (566, 567.22, 567.31, 569.5, 682.9, 998.59), sepsis (995.90, 995.94), intraabdominal hematoma or seroma (998.12, 998.13), and pain (338.1, 388.72). We also separated the length of hospitalization into less than 3 days and 3 days or more. The same outcomes were analyzed in three categories: open, laparoscopy, or robotic-assisted surgery. All complications were measured in the same admission.
An initial analysis was performed describing baseline characteristics in the study population. Subsequently, we conducted Pearson χ2 tests for any compared with no adhesion barriers after myomectomy or hysterectomy according to the included outcomes. Finally logistic regression analyses were conducted to assess adjusted effects of the use of adhesion barriers on perioperative complications. These analyses were performed through an adjusting analysis for age category, race, comorbid illnesses, insurance provider, hospital location, and year. In this regression analyses, no barrier group was used as reference category. Statistical analysis was performed using SAS Enterprise Guide 6.1.
The use rates of adhesion barrier at hysterectomy or myomectomy are shown in Table 1. Compared with that in hysterectomy, more adhesion barriers were used in myomectomy. Of a total 473,788 women, 62,563 women underwent a myomectomy and 411,225 others a hysterectomy. Adhesion barrier was used only in 8,982 procedures (1.9%), 3,392 in myomectomy and 5,590 in hysterectomy. Baseline characteristics of the patients are shown in Table 2. Overall, the age of the patients in the myomectomy group was 37.0±7.8 years (nonbarrier) and 36.0±6.3 years (with barrier) and in the hysterectomy group was 46.0±8.2 years (nonbarrier) and 46.0±8.4 years (with barrier).
The rate of ileus after myomectomy with the use of adhesion barrier was 3.2% (109/3,392) and without the barrier was 2.2% (1,290/59,171, odds ratio [OR] 1.50, 95% confidence interval [CI] 1.22–1.83). The rate of ileus after hysterectomy with the use of barrier was 5.1% (288/5,590) and without the barrier was 2.5% (10,329/405,635), respectively (OR 1.97, 95% CI 1.75–2.23) (Tables 3 and 4). Small bowel obstruction in the immediate postoperative period was uncommonly encountered but was higher after hysterectomy when an adhesion barrier was applied (23/5,590 [0.4%] compared with 804/405,635 [0.2%], OR 1.90, 95% CI 1.25–2.89). Compared with the nonadhesion barrier group, the rate of postoperative fever among those who had an adhesion barrier were also higher after myomectomy (OR 1.44, 95% CI 1.21–1.71) as well as after hysterectomy (OR 1.65, 95% CI 1.40–1.96). The rate of intraabdominal hematoma after hysterectomy was significantly higher in the adhesion barrier group, but comparable after myomectomy. Postoperative pain was more frequently encountered after hysterectomy when an adhesion barrier was used. The length of hospitalization of 3 days or more was also increased when an adhesion barrier was used at hysterectomy (Tables 3 and 4).
When we divided the cases based on three surgical approaches (open surgery, laparoscopy, and robotic-assisted surgery), we found that the rate of ileus and fever was increased with the use of an adhesion barrier after open myomectomy (ileus rates 106/339 [3.3%] compared with 1,217/591,71 [2.1%]; OR 1.54, 95% CI 1.25–1.89) and fever (148/3,392 [4.5%] compared with 1,646/59,171 [2.9%]; OR 1.46, 95% CI 1.23–1.74), but was comparable after laparoscopy or robotic-assisted surgery.
In our study, the use of an adhesion barrier is associated with the risk of increased postoperative fever and ileus, especially after myomectomy or hysterectomy by laparotomy. In addition, the use of an adhesion barrier at open hysterectomy increases the risk of small bowel obstruction in the immediate postoperative period. In a report of 3,229 women who underwent a hysterectomy for a benign condition, the overall incidence of small bowel obstruction after a hysterectomy was 0.5%,1 which was much smaller than we previously reported.4 This could be the result of the small sample size in our previous study.4 In those studies, bowel obstruction was encountered years after the hysterectomy. Among patients who underwent myomectomy, ileus and fever were associated with anti-adhesion barriers only after laparotomy.
Small bowel obstruction after a hysterectomy in the immediate postoperative period with the use of an adhesion barrier was seen more often after hysterectomy when an adhesion barrier was applied (0.20% compared with 0.41%). Whether the surgeons decided to use an adhesion barrier for patients prone to develop severe adhesions and bowel obstruction was unclear. Bashir et al5 also reported that the incidence of ileus and bowel obstruction among patients who underwent a hysterectomy and the use of a sodium hyaluronate–carboxymethylcellulose adhesion barrier were significantly higher than in those without the use of adhesion barrier (12% compared with 7% and 1% compared with 0.7% respectively). The use was also associated with the leak of intestinal anastomosis leading to the risk of abscess after colectomy.
In agreement with previous reports,5,6 we found an increasing use of adhesion barriers in the past several years, especially after a myomectomy (Table 1). However, it is used only in a very small proportion of women (1.9%). It suggests that most gynecologists do not perceive the importance of postoperative adhesion and its sequelae. The use of adhesion barrier is more common after myomectomy than after hysterectomy. It is most likely attributable to the fact that myomectomy is usually performed in premenopausal women in whom there is a concern of adhesion-related infertility.7 Because bowel obstruction-related adhesion tends to occur many years after a hysterectomy,4 most gynecologists do not usually use an adhesion-reducing substance.
The limitations of our study include its retrospective nature, lack of detailed information about the surgery, inability to obtain information about the type of adhesion barriers, and unclear criteria to diagnose ileus or bowel obstruction. In addition, administrative databases can be inaccurate and we could not validate by direct chart review. Not knowing the type of adhesion barrier is a major weakness of our study. However, the most commonly used adhesion barriers are sodium hyaluronate–carboxymethylcellulose8–10 and oxidized regenerated cellulose.11–13 Accordingly, one can assume that those are the adhesion barriers used in our study. Because oxidized regenerated cellulose is easier to use than hyaluronate–carboxymethylcellulose, especially by laparoscopy, it is possible that oxidized regenerated cellulose was the most widely used adhesion barrier in our study.
The strength of our study is that we studied a large number of patients. We found that the use of an adhesion barrier was not without complications, yet the incidence was low. We also found that the use of an adhesion barrier might lead to longer hospitalization. Accordingly, one should weigh the benefits, the risks, and the financial implications of applying adhesion barriers. The use of an adhesion-reducing substance is more beneficial in an infertile woman undergoing a myomectomy than in a menopausal woman undergoing a hysterectomy.
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