The Effect of Diathermy Power Settings on Oral Cavity Mucosal Contraction: A Rat Model Anton Warshavsky, MD ; Shaked Shivatzki, MD; Liyona Kampel, MD; Leonor Leider-Trejo, MD; Udi Shapira, MD; Nidal Muhanna, MD, PhD; Omer J. Ungar, MD ; Dan M. Fliss, MD; Ilana Kaplan, DMD; Gilad Horowitz, MD Objectives/Hypothesis: The effects of different electrocautery power settings on mucosal contraction and margin status in the oral cavity have not been well established. The aim of this study was to examine how different levels of electrocautery energy outputs affect oral mucosal tissue margins. Study Design: Animal model. Methods: A model of 23 adult rats was used (two specimens per rat). After anesthetizing the animals, a 6-mm biopsy punch marked the resection margin on the buccal mucosa (one per cheek). The specimens were excised by means of three energy levels, a cold knife, and monopolar diathermy that was set on either 20 W or 30 W cut modes. The specimens were evaluated for extent of contraction. Results: A total of 45 samples were obtained and measured, including 15 specimens in the cold-knife group, 15 specimens in the 20 W group, and 15 specimens in the 30 W group. The median diameters of the specimens after resection were 4.5 mm for the cold-knife group (interquartile range [IQR] = 4.0–5.0), 3.5 mm for the 20 W group (IQR = 3.5–4.0), and 2.8 mm for the 30 W group (IQR = 2.5–3.0). Specimen contraction was 25.0%, 41.7%, and 53.3%, respectively. The difference in shrinkage between each pair was statistically significant: cold knife versus 20 W, P = .001; cold knife versus 30 W, P < .0001; and 20 W versus 30 W, P < .001. Conclusions: Diathermy power settings result in a significant difference of mucosal tissue contraction, with higher out- puts resulting in a narrower mucosal margin. It is imperative that the surgical team take into consideration the diathermy set- tings during initial resection planning. Key Words: Electrocautery, mucosa, contraction, shrinkage, margins. Laryngoscope, 00:1–5, 2020 INTRODUCTION One of the primary goals of surgically treating oral cavity cancer is achieving negative resection margins. 1,2 After completion of the resection, accurate measurement of tumor margins is critical, because the final margin sta- tus will determine the need for further adjuvant treat- ment. 3 It is not uncommon to find discrepancies between mucosal margin measurements as recorded at the time of surgery and those reported by the pathologist. 4 Reasons for such discrepancies may include: 1) microscopic tumor infiltration not detected by gross inspection and palpa- tion, 2) intrinsic contractility of mucosal tissues, 3) effects of tissue processing and formalin fixation, or 4) some com- bination of the above. 4 The natural shrinking effect of the mucosal margins is a well-known phenomenon that takes place in pathological specimens. 5 Margin contraction in patients with oral cavity cancer was reportedly in the order of 20% to 25% in various oral cavity sub- sites. 6 Discrepancies between surgical and patholog- ical margins may be as high as 60%, depending upon tumor location in the oral cavity. 7 These figures pro- vide a rough rule-of-thumb for surgeons, who will need to add tissue between the tumor and the blade to achieve the desired margin radius. Therefore, it is critical to understand the true order of mucosal con- traction after surgical excision to correctly guide the surgeon and to determine if the classical 1-cm surgi- cal margin is prudent. 8 The use of electrocautery and the effect of its vari- ous diathermy power settings on oral mucosal contrac- tion, has been poorly studied in the past. The variations in heat generated from diathermy may drive the biologi- cal effect leading to the inconsistent results of margin shrinkage. Therefore, the aim of this study was to exam- ine the effect of different electrocautery energy outputs on mucosal contraction and margin status in the oral cavity. From the Department of Otolaryngology, Head and Neck Surgery and Maxillofacial Surgery (A.W., S.S., L.K., U.S., N.M., O.J.U., D.M.F., I.K., G.H.), Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Tel Aviv Sourasky Medical Center (L.L.-T.), Institute of Pathology, Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel. Editor’s Note: This Manuscript was accepted for publication on September 16, 2020 † I.K. and G.H. contributed equally to this work. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Anton Warshavsky, MD, Department of Otolaryngology, Head and Neck Surgery, Tel Aviv Sourasky Medical Cen- ter, 6 Weizmann Street, Tel Aviv 6423906, Israel. E-mail: anton. warshavsky@gmail.com DOI: 10.1002/lary.29155 Laryngoscope 00: 2020 Warshavsky et al.: Effect of Electrocautery on Mucosal Margins 1 The Laryngoscope © 2020 American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA)