Comparison of barbed and conventional sutures in adhesion formation and histological features in a rat myomectomy model: randomized single blind controlled trial

Comparison of barbed and conventional sutures in adhesion formation and histological features in a rat myomectomy model: randomized single blind controlled trial

European Journal of Obstetrics & Gynecology and Reproductive Biology 185 (2015) 121–125 Contents lists available at ScienceDirect European Journal o...

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European Journal of Obstetrics & Gynecology and Reproductive Biology 185 (2015) 121–125

Contents lists available at ScienceDirect

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Comparison of barbed and conventional sutures in adhesion formation and histological features in a rat myomectomy model: randomized single blind controlled trial Murat Api a, Aysen Boza b,*, Muzaffer Seyhan Cıkman a, Figen Vardar Aker c, Mine Onenerk c a b c

Zeynep Kamil Women and Children Diseases Training and Research Hospital, Department of Obstetrics and Gynecology, Istanbul, Turkey Goztepe Training and Research Hospital, Department of Obstetrics and Gynecology, Istanbul, Turkey Haydarpasa Numune Training and Research Hospital, Department of Pathology, Istanbul, Turkey



Article history: Received 2 October 2014 Received in revised form 18 November 2014 Accepted 21 November 2014

Objective: To compare the adhesion and histologic scoring of barbed and standard suture material after incision and serosal closure of both uterine horns for myomectomy model in rats. Study design: In this single blind randomized controlled trial, one cm incisions were performed on the right and left uterine horns of ten non-pregnant rats, and these incisions were randomly allocated for closure by a suture material with either polyglyconate (V-LocTM) or polyglactin-910 (Vicryl1). Each rat served as its own control. Six weeks after the operation, the abdomen was re-opened and the abdominal and surgical sites were evaluated by a researcher blinded to the side of the suture materials in the first operation. Adhesions were scored according to their severity, and specimens were also evaluated and scored histologically according to the following features: collagen deposition and inflammatory reaction. Results: The median macroscopic adhesion scores in the barbed and standard suture group were 3.5 and 2, respectively (p = .008). There was significant difference between the barbed and standard suture group with regard to the median inflammatory cell scores for macrophages-foreign body giant cell (1 vs. 3, respectively, p = .01) and mononuclear cell (2 vs. 3, respectively, p = .04). Conclusion: Based on the results of the present study, we suggest that in the rat model, the type of the suture used for myometrial closure has an effect on subsequent adhesion formation, and this adverse outcome was more frequently observed with the barbed suture. ß 2014 Elsevier Ireland Ltd. All rights reserved.

Keywords: Barbed Suture Rat Adhesion

Introduction Barbed sutures have recently been introduced in gynecology practice to facilitate suturing especially in laparoscopic procedures. Polyglyconate barbed suture material (V-LocTM, Covidien, Mansfield, MA) was approved by the US Food and Drug Administration for soft tissue approximation in 2009. The barbes allow approximating the tissues without the need to tie the surgical knots. Several studies were published to describe the effectiveness of barbed suture and it was reported that the barbed sutures decrease the operation time and the amount of intraoperative bleeding [1,2]. In spite of several potential advantages of barbed sutures which make it more preferable, when it is used intra-abdominal surfaces, the adhesion formation or inflammation

* Corresponding author at: Doctor Erkin Street, 34722 Kadikoy, Istanbul, Turkey. Tel.: +90 530 923 00 46; fax: +90 216 566 40 00. E-mail address: [email protected] (A. Boza). 0301-2115/ß 2014 Elsevier Ireland Ltd. All rights reserved.

due to the barbes has not been adequately studied. Some case reports revealed that this barbed suture material can cause small bowel obstruction or volvulus after its intra-abdominal placement [3–5]. Nevertheless, Einarsson et al. recently published two articles investigating macroscopic and microscopic effects of barbed suture material on 23 sheep uterus, which were operated laparoscopically, the results revealed that no statistically significant adhesion formation was shown when using barbed suture material in comparison to standard suture material [6,7]. Postoperative intra-abdominal adhesions are important health problems which subsequently occur in more than 90% of all patients after undergoing major abdominal surgery [8]. These adhesions usually involve the peritoneum, bowel, and omentum which may cause adverse outcomes such as bowel obstruction, chronic postoperative pain, and injury to the intra-abdominal organs [9–12]. This mechanical barrier increases the risk of infertility [13]. The barbed sutures were commonly preferred in laparoscopic closure of myomectomy procedures or cuff suturing after hysterectomy because of decreasing the operation time and


M. Api et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 185 (2015) 121–125

easing the use of suture. In most theoretical pathways discussing adhesion formation, the inflammatory reaction is considered to be an important aetiological factor [14–16]. Sutures used in pelvic surgery may cause macroscopic adhesions which increase the risk of infertility and also may induce cellular and humoral immunity which results in postoperative adhesion and pain. Therefore, besides macroscopically observed adhesions, there are also histologic changes hidden under the adhesions which should be also taken into consideration in abdomino-pelvic surgery. The aim of the present study is to compare the unidirectional barbed suture with standard suture in a rat myomectomy model with regard to macroscopic adhesion formation and histologic changes.

Materials and methods Our animal model consists of non-pregnant rats with an intact uterus. The study was approved by Marmara University Animal Care, Use and Ethics Committee (No: 38.2014.mar). All aspects of the animal use were in accordance with the guidelines for ethical conduct in the care and use of animals. Ten sexually mature, non-pregnant, female Sprague Dawley albino rats (weight, 196–281 g) were caged under conditions of constant temperature (21–22 8C) and humidity (40–50%), with a 12-hour darklight cycle. The rats were numbered sequentially and provided free access to water and standard rodent chow. All rats were anesthetized via intraperitoneal injection of 100 mg/kg ketamin and 10 mg/kg xylazine hydrochloride. The abdominal skin was shaved, and 10% povidone iodine was applied for antisepsis. Sterile latex gloves were used during all surgical procedures. Researchers (M.A. and M.S.C.) made a midline abdominal vertical incision approximately 5 cm long to expose the uterine horns. Scalpel (No. 15) was used to create a 1.5 cm incision on the anti-mesosalpingeal side of both uterine horns to mimic a myomectomy wound. The decision determining which side of the uterine horn will be sutured with which type of suture material was provided using a computerized random-number generator. The uterine horns of the bicornuate uterus were sutured by using 3-0 polyglactin 910 (Vicryl1) on one side and 3-0 polyglyconate unidirectional barbed suture (V-LocTM) on the other side (Fig. 1). Three times continous unlocked manner suturing was performed without any knot, on the both uterine horns. Blood and fibrin material were removed by rinsing with serum pyhsiologic solution from the surgical site after confirming that hemostasis

had been achieved, and the abdominal wall was closed in a double layer using 3-0 polyglactin 910 suture. Six weeks later, all rats were sacrificed with penthobarbital 300 mg/kg, and a second look laparatomies were performed. The intra-peritoneal and surgical site macroscopic adhesions were identified and scored using an established adhesion scoring system [17] by the researcher (A.B.) blinded to the previous allocation of suture sides in each animal. Adhesion scoring was graded with 1–4 scale as showing no adhesion (score = 1) and very dense adhesion requiring sharp dissection (score = 4) (Fig. 2). In the fresh tissue at second look operation, A.B. examined all intra-abdominal possible adhesion locations; under the laparotomy incision, between the intestinal loops, omentum, uterine horns, etc. by careful manipulation with a fine tissue holder. Under the laparotomy incisions and at the site of operative fields, panoramic views from the most highlighted demonstration of adhesions have been photographed to record for the study archives. For the intra-observer variability, 30 photographic images were randomly selected among the archive and re-evaluated by A.B. in two different occasions; in the 1st observation photographs were consecutively numbered and the 2nd observation they were shuffled. The results of two observations scored by A.B. were statistically analyzed by Cohen’s Kappa test. After completing macroscopic scoring, the left and right horns were completely excised and prepared for tissue section and staining with hematoxylin–eosin for inflammatory cell reaction and Masson’s trichrome stains for estimation of collagen fibers. The histologists (M.O. and F.V.A.) blinded to the suture sides evaluated the specimens under a light microscope and scored them. A 0–3 scale (0 = none, 1 = minimal, 2 = mild, 3 = extensive) was used to score the inflammatory cells (eosinophils, neutrophils, mononuclear cells and foreign body giant cells) and collagen fibers [18]. The presence of the part of sutures remained without being absorbed was evaluated under a light microscope by using both polarized and non-polarized filter. Digital images were obtained using an Olympus BX 53 Light microscope (Fig. 3). All statistical analyses were performed using SPSS software (version 15; SPSS Inc., Chicago, IL) and STATA (version 13, StataCorp LP, Texas USA) was used for power calculation. Median adhesion and histologic scores within the groups were compared by using the Mann–Whitney U test. The Fisher exact test was used to compare the proportion of the presence of adhesions between the groups. Values of p < .05 were considered statistically significant. Since the sample size is decided by the Animal Care and Use Committee with the maximum number of 10 rodents allowed, power calculation was performed retrospectively using the following parameters. By choosing type 1 error .05 based on a two-sided test, with known mean adhesion scores and standard deviations (3.3 and .94 for barbed suture group; 2.1 and .87 for standard suture group), we calculated a power of 79%. Results

Fig. 1. Photographic illustration of suture materials under 40 high power field light microscope (upper is polyglactin-910 No: 3-0 and lower is polyglyconate barbed No: 3-0).

All 10 rats were included to the final analyses without any dropout. The macroscopic adhesion scores were evaluated and recorded for each horn seperately. The median macroscopic adhesion scores at the suture side in the barbed and standard suture group were 3.5 and 2, respectively (p = .008) (Fig. 4). Intestinal involvement in the adhesions was 20% and 10% in the barbed and standard suture group, respectively (p = .5). Intra-rater (A.B.) agreement on macroscopic adhesion scores (obtained from the 30 randomly selected still images) had a Kappa value of .82 (p < .001). Histologic scores were investigated in the pieces of tissues removed from the suture sides (Table 1). Collagen deposition was equally observed between the groups. The median scores of inflammatory cell reaction as shown by eosinophil-neutrophils;

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Fig. 2. Macroscopic view of Y-shapped rat uterus with adhesion formations at second look laparotomy. (a) Score 1: uterine horns without adhesion; (b) score 2: filmy adhesion (*) on left uterine horn; (c) score 3; dense adhesion (#) between the uterine horns; (d) score 4; several very dense adhesions (a) around the uterine horns.

macrophages-foreign body giant cell and mononuclear cell in the barbed and standard suture group were 2 and 3 (p = .15); 1 and 3 (p = .01) and, 2 and 3 (p = .04), respectively.

Comments In this experimental rat model, intra-abdominal placement of barbed suture material seems to have disadvantages in comparison to standard suture material in terms of macroscopic adhesion formation. Although barbed suture material bears the advantages of ease of use without knot tying, less operation time, and bleeding [1,2,19], the adhesion formation is an important aspect. Donellian and Mansuria reported a small bowel obstruction resulting from laparoscopic vaginal cuff closure with a V-LocTM barbed suture material after laparoscopic hysterectomy [3]. Thubert et al. reported a case of bowel volvulus following peritoneal closure using V-LocTM barbed suture material [5]. In another recent publication, Salminen et al. demonstrated three cases of small bowel obstruction after laparoscopic ventral rectopexy using the V-LocTM suture [4]. There was no experimental human study comparing barbed and standard suture material for intraabdominal adhesions. Sutures which are a part of all operative procedures, are frequently described to be part of postsurgical adhesion formation [20]. In former studies, adhesions were found either to extend from sutures themselves or from their direct surroundings. It was concluded that suture material was more paramount in inducing adhesions than diameter size or knot configuration [21]. Both sutures used in our study were in the same diameter and length without any knot to obtain the homogenity between the groups.

The choice of suture material in laparoscopic myomectomy varies between surgeons and is based on perceived differences in clinical practice. Since the barbed suture has been newly introduced, the study designs compared the standard suture with barbed suture have been increasingly published. However, to our knowledge, relative outcome differences between unidirectional barbed suture and standard suture material in this kind of setting has not been studied previously. Only, Einarsson et al. was evaluated adhesion formation between bidirectional polydioxanone barbed suture (QuillTM) and polyglactin-210 suture (Vicryl1), macroscopically [6] and microscopically [7] in two different papers. In our study model, closure of myometrial incision with V-LocTM produced more adhesions than Vicryl1 suture. In the Einarsson et al. [6] study which compares the adhesion formation and ease of use of bidirectional barbed (QuillTM) vs. traditional suture (Vicryl1) during myometrial closure, they used 23 non-pregnant ewes. Three months later when they compared the adhesion scores, the adhesions were observed 52.2% in the barbed suture groups vs. 43.5% in the Vicryl1 group. Although there was nearly a 10% difference in adhesion formation between the groups in favor of Vicryl1, it was not statistically significant (p = .62). The mean adhesion score was not statistically different between the barbed suture (3.78) vs. the standard suture (3.04), (p = .16). The difference between the results of our study and the Einarsson et al. study can be explained by the animals used (rat vs. ewe), the suture material used (polyglyconate vs. polydioxanone), the follow-up period (6 weeks vs. 3 months), incision type on the uterine horns (by scalpel vs. by harmonic scalpel), and the adhesion scoring system used (Garrard vs. Balbinotto) [17,22]. The power of our study and the Einarsson et al. study were 79% vs. 80%, respectively. These conflicting results


M. Api et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 185 (2015) 121–125

Fig. 3. Representative tissue specimens of hematoxylin–eosin (a–c) and Masson’s trichrome (d) (original magnification 40). Increased inflammatory reactions ((a) score = 1, (b) score = 2, (c) score = 3), absence of collagen deposition within and around the suture material (d) and the remaining part of V-LocTM and Vicryl1 suture material were seen.

suggest that there is still need to conduct well designed, randomized, and blinded controlled studies. In the literature, different sutures are known to induce different inflammatory reactions [23,24], while the inflammatory reaction itself is frequently assumed to be an important factor of adhesion formation [14–16]. Microscopically, the collagen deposition and inflammatory reaction scores were similar between the groups. The macrophages-foreign body giant cell and mononuclear cells were more commonly observed in the standard suture group than the barbed suture group. Our histologic results were similiar with the results of Einarsson et al. study [7] which compared bidirectional barbed suture (QuillTM) and standard suture (Vicryl1) in terms of cellular composition and proliferation of

Fig. 4. Bars represent the median adhesion scores at the second look operation six weeks after the first operation in which both uterine horns incised and randomly assigned for the repair by barbed (V-LocTM) or standard (Vicryl1) suture material in myomectomy model of 10 rats. p calculated by using Mann–Whitney U test.

healing wound. They reported that the ratio between areas occupied by connective tissue elements vs. smooth muscle cells and expression of smooth muscle cells actin was similar between the groups. Our observations suggested that polyglactin-910 containing multifilament suture material provoked more inflammatory reaction than polygylconate containing monofilament suture material. However, it does not translate to the formation of adhesion. The adhesion formation is likely to be the result of the mechanical factors of the suture material rather its chemical component. In a previous study [25], Neff et al. revealed the same amount of adhesion formation obtained in chemically different suture materials (polydioxanone vs. polyglactin). These histologic futures and the different amount of adhesions can be explained by the mechanical effect of the barbed suture material on the intraabdominal peritoneal surfaces. The barbed structure itself by creating a rough enviroment on the peritoneal surface may cause entaglement of the neigbouring tissues that consequently produce adhesions. As already known, the intra-abdominal mesothelial surfaces, the intra-abdominal organs (intestines, omentum) physiologically slides on each other and this relationship protects the intra-abdominal organs from the formation of adhesions. Our study suggests that the barbed structure of the suture material may impede this physiologic mechanism by its physical property rather than its chemical property. The present study has several strengths including the use of animals as their own control, randomization of allocation of suture material, and blinding of the evaluator of adhesion formation and severity. There are also some limitations of this study. Due to the nature of the animal studies, it is uncertain whether the findings of this study are directly transferable to what might be expected in humans. Myomectomy was not performed in rats; rather, this procedure was simulated by creating incision on the uterine horns.

M. Api et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 185 (2015) 121–125 Table 1 The comparison of histologic scores in collagen deposition and inflammatory cell reaction.

Collagen deposition Inflammatory cell reaction Eosinophils-neutrophils Macrophages-foreign body giant cell Mononuclear cells

V-Loc (n = 10) Median (25–75%)

Vicryl (n = 10) Median (25–75%)

p value




2 (1–3) 1 (.5–1.5)

3 (2.5–3) 3 (1.5–3)

.15 .01

2 (1.5–3)

3 (3–3)


p < .05 is considered statistical significance.

It could be argued that the incision closure should evoke a similar adhesion response as with myomectomy, however this is not entirely certain. Nevertheless, the animals served as its own controls, and great care was taken to standardize the procedure for both horns. Although 10 animal allow us to use 20 uterine horns to compare two different suture materials, small sample size is still a limitation of our study. Nevertheless, posthoc power analyses gave us a high level of confidence. Our findings might add important insights to the ongoing discussion of whether the barbed suture material increases the risk of adhesion formation. Human studies on the barbed material have been limited to some variables as operation time and blood loss and it is difficult to design human studies in which second operation is required. Based on the results of the present study, we suggest that, in the rat model, the type of suture used for myometrial closure has an effect on subsequent adhesion formation and this effect increases with using the barbed suture material. Certainly human studies will be required to retest our results. Acknowledgement The authors thank Matthew Haughn for his expert asistance in English language review as a native speaker.

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