Evaluation of the effects of absorbable hemostat on the postoperative adhesion formation in a rat uterine horn adhesion model Dr. Mustafa Taş

Introduction One of the most common complications after pelvic surgery is adhesion formation. Postoperative adhesion formation is significantly associated with several morbidities including infertility, pelvic pain, bowel obstruction, and subsequent intraoperative complications

Methods Twenty, six month old female Wistar-Albino rats weighing 180-210 gr were used in this study. All rats were anesthetized, using ketamine hydrochloride at a dose of 50 mg/kg (Ketalar®, flakon, Eczacibasi, Istanbul, Turkey), and 7 mg/kg of xylazine hydrochloric (Rompun®, Bayer, Germany) was administered intraperitoneally.

A modified rat uterine horn adhesion model was used to induce intra-abdominal adhesion formation

In the control group (Group 1), there was nothing to do on traumatize surface. The absorbable hemostats, Surgicel® (oxidized cellulose polymer) were applied on traumatize surface of all rats in Group 2.

The animals were divided into two groups, each consisting of nine rats; included control group 1 received no drug and adhesion formation; group 2 applied absorbable hemostat and adhesion formation, respectively. All animals underwent relaparatomy 1 month after surgery. And rats in all groups were sacrificed by cervical dislocation and laparotomy was performed for scoring of adhesion formation

Results Eighteen rats survived during the procedure, and two of them were excluded from the study. The adhesion severity, extent and total scores in the groups are summarized in Table 1. The extent, severity and total adhesion scores were significantly higher in absorbable hemostat compared to control.

Group 2 (absorbable hemostat) Table 1. Adhesion scores of the groups     Group 1 (control) Group 2 (absorbable hemostat) Severity 2.20 ± 0.53a 2.80 ± 0.85b Extent 0.61 ± 0.25a 0.92 ± 0.26b Total score 2.81 ± 0.75a 3.72 ± 0.96b

Similarly, immunohistochemical parameters which were commonly seen in adhesion foci were significantly higher in the absorbable hemostat group comparing the control (Table 2). All of the five scores of immunohistochemical parameters were high in group 2.

Group 2 (absorbable hemostat) Table 2. Immunohistochemical scores of the adhesion areas in the groups.   Group 1 (control) Group 2 (absorbable hemostat) PNL index (acute inflammation) 2.15 ±0.51 a 2.32± 0.61 b MNL index (chronic inflammation) 2.10 ± 0.80 a 2.62 ± 0.81 b Ki-67index (proliferation marker) 2.07 ± 0.42 a 2.25 ± 0.66 b CD-31index (neovascularization marker) 1.92 ± 0.51a 2.32 ± 0.45 b Masson Trichrome index (fibrosis marker) 2.02 ± 0.54 a 2.25 ± 0.56 b

(a), (c) control group. (b), (d) absorbable hemostatic group and thick shows cystic formations

Discussion Postoperative adhesion formation that is associated with morbidities such as pelvic pain, ectopic pregnancy, infertility, and surgical complication occurs in 60-90 % of women after gynecological surgery. Furthermore postoperative adhesion formation might be increased after infertility procedures such as myomectomy, laparoscopic cyst excision

Adhesions account for approximately 20 % of all infertility cases depending on previous operation and adhesiolysis has been shown to increase pregnancy rates in more than 50 % of infertile patients after previous laparotomy

Absorbable hemostats might be frequently used during the operations such as myomectomy, all types of laparotomy procedures, and cesarean section. Up to date, there has been no study to evaluate the effects of most frequently absorbable hemostat on adhesion formation and this is the first prospective randomized study to investigate the adhesion effects of absorbable hemostat with using Ki-67, CD-31, MTC, PNL, MNL indexes in a rat model

The most important mechanisms for adhesion formation are inflammatory response that leads to activate the expression of lymphocytes, macrophages, and mesothelial cells

Our study clearly demonstrated that macroscopic and immunohistochemical scores of adhesion formation were increased by absorbable hemostat. Additionally, cystic formation was observed in the absorbable hemostat group.

In conclusion, absorbable hemostats were increased adhesion formation in the rat uterine horn model. We found that absorbable hemostat increased the number and percentage of cells positive for Ki-67, CD-31, MTC in a concentration manner and that PNL and MNL were higher in treatment groups. Absorbable hemostat increased detrimental effects of adhesion formation. Further studies are needed to confirm these results.