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A Suturing Method without Exposure of Barbs on the Wound Surface Using a Unidirectional Barbed Monofilament Absorbable Suture (STRATAFIX™) in Laparoscopic Myomectomy: A Feasibility Study

Objectives: We examined whether a new suturing method that used a single-thread unidirectional barbed suture without exposing the barbs on the wound surface was acceptable compared with the conventional suture method during laparoscopic myomectomy (LM). Materials and Methods: This was a retrospective study. The subjects were 26 women who underwent LM for symptomatic uterine fibroids. The operative time, amount of blood loss, and number of threads used were compared between a group in which suturing was performed with a conventional synthetic absorbable suture (conventional suture group, n = 13) and a group in which suturing was performed using a barbed suture (barbed suture group, n = 13). Results: Operative time in the barbed suture group was significantly shorter than that in the conventional suture group, while blood loss during LM in the barbed suture group was significantly lower than that in the conventional suture group. The number of threads used in the conventional suture group was significantly larger than that in the barbed suture group. No complications were observed in both the groups during LM. Conclusion: This new technique using a barbed suture is safe and feasible for LM.

Herein, we developed a new suturing method that used a single-thread unidirectional barbed suture with a single thread and did not expose barbs on the wound surface during LM and evaluated whether it was clinically acceptable compared with the conventional suturing method.

Ethics
This study was approved by the institutional review board of Kawasaki Medical School (approval no. 3959). Patients who underwent LM provided signed informed consent after receiving counseling on their treatment options.

Study design and setting
This was a retrospective study based on medical records. Data used in this study were collected from January to June 2020. Conventional sutures were used for cases from January to March 2020, and single-thread suturing methods with unidirectional monofilament barbed suture were used for cases from April to July 2020. Cases were divided into the conventional and barbed suture groups, accordingly.

Selection of patients who underwent laparoscopic myomectomy
LM was performed in women who wanted to preserve their uterus and had experienced menorrhagia, dysmenorrhea, pressure symptoms, and infertility. Patients who underwent LM provided signed informed consent after receiving counseling on their treatment options. All patients underwent magnetic resonance imaging to determine the fibroid number, size, and location of the fibroids. Individual fibroids larger than 10 cm in size and type 0 and 1 submucosal fibroids were excluded from the indications for LM. No exclusion criteria were established for the number of uterine fibroids. Other exclusion criteria were as follows: women with age ≥40 years, body mass index ≥30, pregnancy, and systemic complications such as severe cardiovascular disease, pulmonary obstructive disease, and a history of hip replacement surgery.

Laparoscopic surgery setting
All surgical procedures were performed by a single surgeon; LM was performed in the Trendelenburg position under general anesthesia with a four-port 2D/4K laparoscopy system (VISERA 4K UHD Camera Control Unit; Olympus Medical Systems, Tokyo, Japan). A 10-mm trocar (ENDOPATH XCEL ® , Ethicon Endo-Surgery, Cincinnati, OH, USA) for the zero-degree laparoscope was introduced intraumbilically; 3 additional 5-mm lateral trocars (ENDOPATH XCEL ® , Ethicon Endo-Surgery, Cincinnati, OH, USA) were placed centrally and on the left and right flanks under direct vision. The surgeon used the central and left-sided lateral ports to perform most of the procedures. A uterine manipulator was used to mobilize the uterus.

Laparoscopic myomectomy procedure
After setting all trocars, the small intestine was evacuated up to the upper abdomen to secure the laparoscopic operative field. The number and location of fibroids were confirmed and 1 IU of diluted vasopressin in 70 mL normal saline was injected into the uterine wall to reduce intraoperative bleeding. The serosa overlying the fibroid was incised with ultrasonic scissors (Harmonic ® HD1000i, Ethicon Endo-Surgery, Tokyo, Japan) or a monopolar electrode (ENDOPATH ® PROBE PLUS II System, Ethicon Endo-Surgery, Tokyo, Japan) until the fibroid pseudocapsule was reached. When the cleavage plane was identified, the fibroid was fixed with a 5-mm grasper and manually enucleated by traction. Hemostasis was achieved using a bipolar coagulation electrosurgical unit.
In the conventional suture group, a size 0 Vicryl suture in a CT-1 needle (Ethicon Endo-Surgery, Tokyo, Japan) was used to close the myometrium either with two-layer continuous or interrupted sutures or, depending on the incision depth, single-layer sutures. A 45-cm Vicryl piece was cut into 30-cm pieces and used depending on the number of fibroids; 3-6 pieces were used to suture the myomectomy sites. After the first layer was sutured, the second layer (including seromuscular layers) was sutured using the "baseball" suture technique. All myomectomy sites were sutured similarly.
In the barbed suture group, a size 0 STRATAFIX ® Symmetric PDS Plus ® (Ethicon Endo-Surgery, Tokyo, Japan), an absorbable unidirectional barbed suture, in a CT-1 needle was used to close the myometrium with a two-layer continuous suture or, depending on the incision depth, a single-layer suture. The enucleation sites of all uterine fibroids were sutured with a single 45-cm thread. The first layer of sutures was made wider apart than conventional continuous sutures, which was advantageous for hemostasis, as it allows for the tight adherence of multiple muscle layers. The second layer (including seromuscular layers) was sutured using the "baseball" suture technique with a barbed thread, which was different from the common "baseball" suture. In a common "baseball" suture, the needle is inserted through the muscle layer inside the wound surface and passed through the serosal surface separate from the wound edge. The use of barbed thread in this suturing method results in exposed barbs on the muscle fiber surface. In the "baseball" suture with barbed thread (unlike the usual "baseball" suture), the needle with a barbed suture was inserted inside the wound surface and passed through the serosa adjacent to the wound edge to prevent the barbs from surfacing. After suturing one myomectomy site, the needle with the barbed suture was passed through the muscle layer to another myomectomy site; then, the same suture was performed using a barbed thread [ Figure 1 and Video 1 (Video 1 is also available at http://www.apagemit.com/page/video/show. aspx?num=268&page=1)]. After suturing was completed, the barbed thread was carefully cut to prevent the barbs from surfacing.
After suturing, a posterior 1-2-cm transverse colpotomy was performed laparoscopically, precisely in the midline of the posterior vaginal fornix, demarcated using a Vagi-Pipe ® (Hakko Medical, Nagano, Japan). All enucleated fibroids were removed through the colpotomy incision. Finally, the surface of the uterus was covered with a cellulose absorbable adhesion barrier (Interseed, Ethicon Endo-Surgery, Tokyo, Japan). The pneumoperitoneum was desufflated and trocars were removed, followed by closure of all trocar sites. All extirpated tissues underwent histopathological examination to confirm the fibroids.

Evaluation of parameters
We compared the clinical validity of a new barbed suturing method using STRATAFIX ® Symmetric PDS Plus ® with the conventional method using a Vicryl suture. Clinical validity was evaluated by the operative time, blood loss, and number of threads used. Operative time was calculated from the time of pneumoperitoneum creation through desufflation. The amount of bleeding was estimated by subtracting the amount of water used for irrigation from the total suction volume.

Statistical analysis
Data are shown as median (range); all statistical analyses were performed with EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan), which is a graphical user interface for R (The R Foundation for Statistical Computing, Vienna, Austria). [11] Parameters were compared between the conventional and barbed suture groups using the Mann-Whitney U-test. P < 0.05 was considered statistically significant. Table 1. There were no significant differences in age, body mass index, number of fibroids, fibroid maximum diameter, and total weight of the fibroids removed between the conventional suture (n = 13) and the barbed suture groups (n = 13). Operative time in the barbed suture group was significantly shorter than that in the conventional suture group. Blood loss during LM in the barbed suture group was significantly lower than that in the conventional suture group. The number of threads used in the conventional suture group was significantly larger Figure 1: Procedure for the new suturing method using a barbed suture during laparoscopic myomectomy. The myometrium was closed with a two-layer continuous suture using a size 0 STRATAFIX Symmetric PDS Plus in a CT-1 needle (Ethicon Endo-Surgery, Tokyo, Japan). Enucleation sites of all uterine fibroids were sutured with a single 45-cm thread. The first layer of sutures was made wider than the conventional continuous suture, which is advantageous for hemostasis, as it allows for tight muscle layer adherence (a and b, white arrow indicates point of needle insertion; yellow arrow indicates the suture direction). The "baseball" suture technique with a barbed thread was used for the second suture layer. In the "baseball" suture with a barbed thread, the needle with a barbed suture was inserted from the inside and passed through the serosa adjacent to the wound edge to prevent barb surfacing (c, yellow arrow indicates suture direction). After suturing one myomectomy site (d), the needle with the barbed suture was passed through the muscle layer to another myomectomy site; then, the same suture was performed (e)

dIscussIon
This study showed that, when compared with conventional suturing, the new suturing method with a unidirectional barbed suture is feasible for LM. The new suturing method is superior in terms of shortening operative time and reducing the amount of blood loss; moreover, it is not inferior to the conventional method in terms of cost.
First, the point of this new suturing method that uses a barbed suture is that it ensures hemostasis without exposing barbs on the wound surface. In LM, it is common to follow a narrow-pitch design when suturing to achieve hemostasis. However, suturing with a large pitch is advantageous for hemostasis, since this allows for muscle layer involvement when suturing. When the second suture is performed, the needle is inserted at a position far from the wound edge, and the muscle layer is sutured largely by increasing the pitch, like with the first suture. As a result, the barbs reach the wound surface. In other words, in order to prevent the barbs from reaching the wound surface in the second layer when using a barbed thread, it is necessary to insert the needle from one wound edge to the next.
The advantage of this suturing method that does not expose the barbs on the wound surface is the prevention of adhesion between the barbs and the intestine, which is followed by the development of ileus. It has been reported that, when the barbs were exposed on the wound surface, they caused bowel entanglement and subsequent intestinal obstruction. [10,12] Einarsson et al. reported a technique for suturing the first layer with a barbed suture and the second layer with a nonbarbed suture; the barbs were not exposed on the wound surface which prevented the ileus caused by bowel entanglement. [6] Our technique uses a barbed suture in the second muscle layer, but "burying" the barbs within the muscular layer prevents their exposure on the wound surface. In addition, covering of the myomectomy sites with an absorbable adhesion barrier is recommended in anticipation of barbs appearing due to muscle shrinkage after surgery. This is also effective in preventing pelvic adhesions.
Second, the point of this new suturing method with a barbed suture is that multiple enucleation sites are sutured with a single barb. After suturing one fibroid enucleation site, the needle is inserted into the muscle layer, and brought out at the bottom of the wound at another fibroid enucleation site, and the other site is sutured. Using this method, multiple enucleation sites could be sutured with a single barbed thread.
Suturing with a single barbed thread has two advantages: less time required for inserting and removing the needle through the trocar, and reduced cost by not using multiple threads. A barbed suture is more expensive than conventional synthetic absorbable suture. In this study, all cases were sutured with a single barbed thread. The prices of barbed or Vicryl sutures vary between hospitals; therefore, it is not possible to evaluate them accurately for all institutions. However, the difference is likely to be several times that of the actual price per thread. Since the median number of Vicryl threads used in a single-session surgery was 4 (range, 3-5), the total cost of barbed sutures is comparable to that of the conventional method using Vicryl sutures.
The limitations of this study were the subject selection bias due to the retrospective nature of the study. A prospective randomized controlled trial is required in this regard. In addition, in this study, it was necessary to examine whether similar procedures could be performed by other surgeons who had performed suturing operations by one surgeon, in order to eliminate variations between surgeons.

conclusIon
The new suturing method that used barbed sutures resulted in shorter operative time and less blood loss during LM,