• Doç. Dr. OZAN ŞEN

Scientific Publications

Assoc. Dr. The majority of Ozan Şen's scientific articles, including his experiences in Obesity and Reflux surgery, are published in prestigious international journals. Gaining great experience in Obesity and Reflux surgery in the last 10 years, Dr. Ozan Şen continues his work in this field.

Articles Published in International Group A Journals

Ozan Sen, Ahmet G. Turkcapar. Review of our experience using modified staple line suturing technique in laparoscopic sleeve gastrectomy Surg Laparosc Endosc Percutan Tech. 2021 Doi: 10.1097/SLE.0000000000001024
https://pubmed.ncbi.nlm.nih.gov/34966154/

Abstract

Background: Laparoscopic sleeve gastrectomy (LSG) has become the most common bariatric surgical method in recent years. Although LSG provides good outcomes, serious complications such as leakage, bleeding, and stenosis may develop postoperatively. Numerous staple line reinforcement methods have been used to reduce complications. Whether each one of these practices is effective remains controversial.

Aim: Our study aims to assess outcomes and safety of modified (purse-string+oversewing) staple line suturing technique for patients who underwent LSG.

Materials and methods: A total of 505 patients who underwent LSG with modified staple line suturing technique between March 2018 and February 2021 were included in this retrospective study. Age, sex, body mass index, operation time, perioperative and postoperative 30-day complications were recorded in all patients.

Results: Of 505 patients (59.6% female) with a mean age of 37.6 years (minimum to maximum: 12 to 68 y) and median body mass index of 40.2 kg/m2 (minimum to maximum: 32 to 75 kg/m2) underwent LSG. LSG was performed as revision surgery in 17 (3.4%) patients. Five (1%) patients also underwent concomitant cholecystectomy. The mean operation time was 92 minutes (75 to 110 min) in our primary LSG cases. Operative complications included minor hepatic injury in 8 (1.6%) and anesthesia awareness in 3 (0.6%) patients. Postoperative included bleeding which occurred in 2 (0.4%) patients, portomesenteric vein thrombosis in 1 (0.2%), and minor wound infection in 3 (0.6%) patients. There was no leak, no stenosis, and no mortality.

Conclusion: Sleeve gastrectomy with modified staple line suturing technique is an effective method and could be safely applied with low morbidity.

Singhal R, Ludwig C, Rudge G, Gkoutos GV, Tehrani A, Sen O, Mahawar K. 30-Day morbidity and mortality of bariatric surgery during the Covid-19 pandemic: a multinational cohort study of 7704 patients from 42 countries. Obes Surg 2021;31:4272-88
https://pubmed.ncbi.nlm.nih.gov/34328624/

Abstract

Background: There are data on the safety of cancer surgery and the efficacy of preventive strategies on the postoperative symptomatic COVID-19 in these patients. But there is little such data for any elective surgery. The main objectives of this study were to examine the safety of bariatric surgery (BS) during the coronavirus disease 2019 (COVID-19) pandemic and to determine the efficacy of perioperative COVID-19 protective strategies on symptomatic COVID-19 rates.

Methods: We conducted an international cohort study to determine all-cause and COVID-19-specific 30-day morbidity and mortality of BS performed between 01/05/2020 and 31/10/2020.

Results: Four hundred ninety-nine surgeons from 185 centers in 42 countries provided data on 7704 patients. Elective primary BS (n = 7084) was associated with a 30-day morbidity of 6.76% (n = 479) and a 30-day mortality of 0.14% (n = 10). Emergency BS, revisional BS, insulin-treated type 2 diabetes, and untreated obstructive sleep apnoea were associated with increased complications on multivariable analysis. Forty-three patients developed symptomatic COVID-19 postoperatively, with a higher risk in non-whites. Preoperative self-isolation, preoperative testing for SARS-CoV-2, and surgery in institutions not concurrently treating COVID-19 patients did not reduce the incidence of postoperative COVID-19. Postoperative symptomatic COVID-19 was more likely if the surgery was performed during a COVID-19 peak in that country.

Conclusions: BS can be performed safely during the COVID-19 pandemic with appropriate perioperative protocols. There was no relationship between preoperative testing for COVID-19 and self-isolation with symptomatic postoperative COVID-19. The risk of postoperative COVID-19 risk was greater in non-whites or if BS was performed during a local peak.

Keywords: Bariatric surgery; COVID-19; Obesity surgery; Pandemic; revisionalsurgery; SARS COV-2.

Singhal R, Wiggins T, Super J, Alqahtani A, Nadler EP, Ludwig C, Sen O, Tehrani A, Mahawar K. 30-Day morbidity and mortality of bariatric metabolic surgery in adolescents during the Covid-19 pandemic- The GENEVA study. Pediatric Obes. 2021;16:12832.
https://pubmed.ncbi.nlm.nih.gov/34240553/

Abstract
Background: Metabolic and bariatric surgery (MBS) is an effective treatment

for adolescents with severe obesity.

Objectives: This study examined the safety of MBS in adolescents during the coronavirus disease 2019 (COVID-19) pandemic.

Methods: This was a global, multicentre and observational cohort study of MBS performed between May 01, 2020, and October 10,2020, in 68 centers from 24 countries. Data collection included in-hospital and 30-day COVID-19 and surgery-specific morbidity/mortality.

Results: One hundred and seventy adolescent patients (mean age: 17.75 ± 1.30 years), mostly females (n = 122, 71.8%), underwent MBS during the study period. The mean pre-operative weight and body mass index were 122.16 ± 15.92 kg and 43.7 ± 7.11 kg/m2 , respectively. Although majority of patients had pre-operative testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (n = 146; 85.9%), only 42.4% (n = 72) of the patients were asked to self-isolate pre -operatively Two patients developed symptomatic SARS-CoV-2 infection post-operatively (1.2%). The overall complication rate was 5.3% (n = 9). There was no mortality in this cohort.

Conclusions: MBS in adolescents with obesity is safe during the COVID-19 pandemic when performed within the context of local precautionary procedures (such as pre-operative testing). The 30-day morbidity rates were similar to those reported pre-pandemic. These data will help facilitate the safe re-introduction of MBS services for this group of patients.

Keywords: COVID-19; SARS COV-2; bariatric surgery; pandemic.

Singhal R, Wiggins T, Super J, Alqahtani A, Nadler EP, Ludwig C, Sen O, Tehrani A, Mahawar K. 30-day morbidity and mortality of sleeve gastrectomy, Roux-en-Y gastric bypass an done anastomosis gastric bypass: a propensity score-match analysis of the GENEVA data. Int J Obes 2021;15:1-8
https://pubmed.ncbi.nlm.nih.gov/34912046/

Abstract
Background: There is a paucity of data comparing 30-day morbidity and mortality of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one anastomosis gastric bypass (OAGB). This study aimed to compare the 30-day safety of SG, RYGB, and OAGB in propensity score-matched cohorts.

Materials and methods: This analysis utilised data collected from the GENEVA study which was a multicentre observational cohort study of bariatric and metabolic surgery (BMS) in 185 centers across 42 countries between 01/05/2022 and 31/10/2020 during the Coronavirus Disease -2019 (COVID-19) pandemic. 30-day complications were categorised according to the Clavien-Dindo classification. Patients receiving SG, RYGB, or OAGB were propensity-matched according to baseline characteristics and 30-day complications were compared between groups.

Results: In total, 6770 patients (SG 3983; OAGB 702; RYGB 2085) were included in this analysis. Prior to matching, RYGB was associated with highest 30-day complication rate (SG 5.8%; OAGB 7.5%; RYGB 8.0% (p = 0.006)). On multivariate regression modeling, Insulin-dependent type 2 diabetes mellitus and hypercholesterolaemia were associated with increased 30-day complications. Being a non-smoker was associated with reduced complication rates. When compared to SG as a reference category, RYGB, but not OAGB, was associated with an increased rate of 30-day complications. A total of 702 pairs of SG and OAGB were propensity score-matched. The complication rate in the SG group was 7.3% (n = 51) as compared to 7.5% (n = 53) in the OAGB group (p = 0.68). Similarly, 2085 pairs of SG and RYGB were propensity score-matched. The complication rate in the SG group was 6.1% (n = 127) as compared to 7.9% (n = 166) in the RYGB group (p = 0.09). And, 702 pairs of OAGB and RYGB were matched. The complication rate in both groups was the same at 7.5 % (n = 53; p = 0.07).

Conclusions: This global study found no significant difference in the 30-day morbidity and mortality of SG, RYGB, and OAGB in propensity score-matched cohorts.

Ozan Sen, Ahmet G. Turkcapar. Effect of pre-operative weight loss on patients'outcomes undergoing laparoscopic sleeve gastrectomy. Journal of Minimal Access Surgery 2021. Article in press
https://pubmed.ncbi.nlm.nih.gov/34045397/

Abstract
Background: The study aims to demonstrate whether weight loss with a low-calorie diet before laparoscopic sleeve gastrectomy (LSG) may affect the outcomes.

Materials and methods: A total of 305 patients undergoing primary LSG were included in the study. Each patient adopted a low-calorie diet (1000 calories) before LSG. The patients were stratified into two groups. Group A: Those who lost 3% or more of their total body weight loss (TBWL), Group B: Those who lost <3% of their TBWL. Two groups were compared in terms of operative time, length of hospital stay, complications and weight loss outcomes.

Results: One hundred and five patients (35%) were in Group A and 200 patients were in Group B. Median weight loss was 4 kg (3-20 kg). Pre-operative mean body mass index (BMI) was 40 ± 7.4 kg/m2 in Group A and 41 ± 5.9 kg/m2 in Group B (P = 0.06). at 1 year

after the surgery, BMI regressed to 29.7 ± 4.9 kg/m2 in Group A and to 27 ± 4.2 kg/m2 in Group B (P < 0.001). One hundred and twenty-nine patients who completed 2 years of follow-up, mean BMI regressed to 29.4 ± 4.1 kg/m2 in Group A (n = 46) and to 27.2 ± 4.5 kg/m2 in Group B (n = 83) (P < 0.001). In Group B, one patient experienced post-operative bleeding. No other complications were observed in the study. There was no significant difference between the groups in terms of operative time (P = 0.53) and length of hospital stay (P = 0.9).

Conclusion: Weight loss before LSG does not improve post-operative weight loss.

Keywords: Bariatric surgery; pre-operative diet; sleeve gastrectomy; weight loss success.

Ozan Sen, Ahmet G. Turkcapar. Risk of asymptomatic gallstones bocoming symptomatic after laparoscopic sleeve gastrectomy. The American Surgeon 2021. Article in press
https://pubmed.ncbi.nlm.nih.gov/33866854/

Abstract
Background: Whether concomitant cholecystectomy is needed during laparoscopic sleeve gastrectomy (LSG) in patients with asymptomatic cholelithiasis is controversial. In this study, our aim is to show the follow-up results in patients with asymptomatic cholelithiasis who underwent LSG alone.

Methods: Patients undergoing primary LSG between March 2018 and September 2020 with asymptomatic gallbladder stones were included in this retrospective study. All patients underwent abdominal ultrasound (US) before surgery. Patients' demographics and postoperative outcomes were recorded.

Results: A total of 180 patients underwent primary LSG and completed the 1-year follow-up. The study population of 42 patients (23%) with asymptomatic cholelithiasis. The mean age was 41.1±7.1 years (31-56, 63% female), and mean body mass index (BMI) was 44 ± 6.7 kg/m2. Average BMI decreased to 31.1 ± 4.7 kg/m2 at 6 months and to 27.3 ± 3.6 kg/m2 at 1 year. The average follow-up period was 17 ± 5.7 months (range, 12-28 months). Of the 42 patients, only 1 patient (2.4%) became symptomatic during the follow-up period.

Discussion: We do not recommend cholecystectomy in patients with asymptomatic gallstones during the same session with LSG. An observational approach should be adopted for these patients.

Keywords: asymptomatic gallstones; concomitant cholecystectomy; sleeve gastrectomy.

Ozan Şen, Fatih Can Karaca, Seniyye Ulgen Zengin, Ahmet Gökhan Türkçapar. Intraoperative awareness during laparoscopic sleeve gastrectomy. The European Research Journal. 2021 February DOI: 10.18621/eurj.811379
https://dergipark.org.tr/en/pub/eurj/issue/62905/811379

Abstract
Objectives: The aim of this study is to determine the incidence of intraoperative awereness (IA) in our patients who underwent laparoscopic sleeve gastrectomy (LSG) and the factors affecting the formation of this complication.

Methods: Four hundred ten patients who underwent LSG between March 2018 and September 2020 were included in the study. By April 2019, we started using the Bispectral index (BIS) monitoring, which measures the depth of anesthesia in all of our LSG cases (n = 167). Patients with and without BIS monitoring were divided into two groups and compared.

Results: In our series, IA was seen in 3 patients (2 males) in two different hospitals (0.7%; n = 410). They were all in the non BIS group (n = 243). The median duration of anesthesia was 120 minutes (ranging 90-180) in the non-BIS, and 113 minutes (ranging, 90-140) in the BIS group (p < 0.001). Hypotension developed in 63 patients in non-BIS and 12 patients in BIS group at the beginning of the operation (< 90/60 mm Hg). The total remifentanil infusion dose administered during the anesthesia period in the BIS group was 1310 ± 351 mcg, and 1330 ± 270 mcg in the non BIS group (p = 0.002). The effect of BIS monitorization between groups on IA, did not show statistical significance (p  = 0.27).

Conclusions: Anesthesia techniques that work well for patients with normal weight may not be safe and appropriate for obese patients. Especially in patients with intraoperative hypotension, it is necessary to be more careful about dose adjustment of anesthetic drugs.

Ozan Sen, Ahmet Gokhan Turkcapar. Barrett's ulcer 5 years after sleeve gastrectomy: case report and literature review. 2020 December;33(6):344-6
https://www.minervamedica.it/en/journals/chirurgia/article.php?cod=R20Y2020N06A0344

Abstract

Bariatric surgery is the most effective way to treat morbid obesity. Among the surgical methods, sleeve gastrectomy's popularity (SG) has increased tremendously in recent years. Despite the success of the SG, gastro esophageal reflux disease (GERD) remains to be an important problem, postoperatively. Barrett's esophagus (BE) is another considerable point in patients with GERD after SG. GERD, which may occur after SG, is perhaps a serious problem that is underestimated. In such patients with GERD symptoms, preferred approach by bariatric surgeons is to start PPI treatment, which works for the majority of

patients Barrett's esophagus is a precancerous lesion develops on the surface of GERD. Because esophageal mucosa gets desensitizes in Barrett metaplasia, some patients may be completely asymptomatic. In the long-term period after SG endoscopic follow up is very important whether patients are symptomatic or not.

Here, we present the case of a patient who had no GERD symptoms and had completely normal endoscopy preoperatively who later developed dysplastic Barrett's ulcer 5 years after SG. Roux-en-y gastric bypass operation was performed as revisional surgery.

Key words: Bariatric surgery; Gastrectomy; gastroesophageal reflux; Barrett esophagus

Ozan Sen, Ahmet Gokhan Turkcapar. Porto-mesenteric vein thrombosis after laparoscopic sleeve gastrectomy. A case report. International Journal of Surgery Case Reports 2021; 79:424-27
https://pubmed.ncbi.nlm.nih.gov/33524799/

Abstract
Introduction: Porta-mesenteric vein thrombosis (PMVT) is rare but fatal complication in patients who are undergoing bariatric surgery. In this report, we present a rare case of a PMVT after laparoscopic sleeve gastrectomy (LSG).

Case presentation: A 52-year-old male patient with a body mass index of 42 kg/m2 was admitted to our clinic for morbid obesity. Standard LSG was performed with 5 trocar technique. 15 days after LSG, the patient admitted to the emergency department with complaints of abdominal pain, nausea and vomiting. The patient was dehydrated. His C-reactive protein level was 138 mg/L. Abdominal computerized tomography with contrast was performed and showed thickening of a part of small bowel wall in 10 cm length. Also, major thrombosis were detected in the superior mesenteric vein branches and portal vein. The patient was hospitalized and 2 × 10,000 IU/1.0 mL high dosage low molecular weight heparin (LMWH) therapy was initiated. The patient's clinical signs recovered rapidly following treatment.

Clinical discussion: In LSG, if the gastroepiploic venous arcus, which runs along the greater curvatura, and has a direct connection to the portal circulation is damaged, a local thrombus may form and move towards the portal system over time. Dehydration is another significant predisposing factor for PMVT. Some patients may develop life-threatening intestinal ischemia. Abdominal tomography with contrast plays a major role in diagnosis.

Conclusion: PMVT should be considered as a serious complication after LSG in patients with abdominal pain. With early diagnosis and anticoagulant therapy, patients' clinical symptoms may improve quickly.

Keywords: Bariatric surgery; Complication; Laparoscopic sleeve gastrectomy; Porto- Mesenteric vein thrombosis.

Ozan Şen, Ümit Sekman, Ahmet G. Türkçapar, Mehmet A. Yerdel. Does Fixation of Gastric Sleeve Prevent Functional Stenosis in Sleeve Gastrectomy Patients? Surg Laparosc Endosc Percutan Tech. 2020 Oct 29;31(2):220-222.
https://pubmed.ncbi.nlm.nih.gov/33137013/

Abstract
Aim: The aim of this study is to determine whether gastric sleeve fixation prevents functional stenosis (twist or kink) and to investigate its effects on symptoms such as nausea and vomiting after laparoscopic sleeve gastrectomy (LSG).

Methods: A total of 717 patients who underwent primary LSG for morbid obesity and completed at least 1 year of follow-up between 2012 and 2019 were included in the study. All operations were performed by the same surgical team using the same technique. The patients were divided into 2 groups, that is, group 1: standard LSG and group 2: gastric sleeve fixation with LSG. These 2 groups were compared in terms of demographic characteristics, baseline body mass index, follow-up duration, bleeding, leaks, gastric stenosis, postoperative nausea, vomiting, and the need for antiemetics. In the follow-up period, patients with doubts gastric stenosis underwent endoscopy and upper gastrointestinal series.

Results: LSG was performed in 717 patients (55.2% female) with a mean age of 37.8±11.5 years and a median body mass index of 42.2 (30.2 to 74.2) kg/m2. The 241 patients in the first group underwent LSG without fixation, and the 476 patients in the second group with fixation. Functional stenosis was detected in 8 patients, all of whom were in group 1. One patient in group 1 had a leak on the background of functional stenosis. There was bleeding that required transfusion in 2 patients (group 1) and reoperation in 2 patients (group 2). None of the study patients died. During the in-hospital period, 122 (50.6%) patients in group 1 and 159 (33.4%) patients in group 2 had nausea and vomiting that required antiemetic treatment (P<0.001).

Conclusion: Gastric sleeve fixation in LSG prevents complications that may arise because of improper gastric mobilization. This method is effective in reducing nausea and vomiting in LSG patients.

Rishi Singhal, Abd A. Tehrani, Christian Ludwig, Kamal Mahawar, Geneva collobrators (Ozan Şen, Ahmet G. Türkçapar). Global 30-day outcomes after bariatric surgery during the

COVID-19 pandemic (GENEVA): an international cohort study. The Lancet Diabetes & Endocrinology. November 2020 DOI: 10.1016/S2213-8587(20)30375-2.
https://www.thelancet.com/journals/landia/article/PIIS2213-8587(20)30375-2/fulltext

Ozan Sen, Ahmet G. Turkcapar. Combined partial posterior fundoplication with laparoscopic sleeve gastrectomy for morbid obese patients with symptomatic GERD. Video case report. International Journal of Surgery Case Reports 2020; 71:34-36
https://pubmed.ncbi.nlm.nih.gov/32428830/

Abstract
Introduction: Gastroesophageal reflux disease (GERD), which can be seen in up to 30% in postoperative series, is perhaps the most important complication of sleeve gastrectomy(SG). The general trend for patients who are planning to have bariatric surgery and have symptomatic GERD, Roux-en-Y gastric bypass is the most common choice.

Case Presentation and Management: A 42-year-old female patient with a body mass index of 36 kg/m2 presented to our clinic with obesity and symptomatic GERD. She had been using proton pump inhibitor (PPI) regularly for 1 year. Preoperative endoscopy showed hiatal hernia but no esophagitis. The patient underwent ambulatory pH study and GERD was confirmed. The patient was scheduled to have laparoscopic hiatal hernia repair plus combined partial posterior fundoplication and sleeve gastrectomy. Hiatal hernia was repaired, gastric fundus was passed behind the esophagus and partial posterior fundoplication was performed, and than SG was completed. She stopped using PPI in the early postoperative period and her reflux symptoms disappeared completely. The patient lost 20 kg in the 3rd month (40% ewl) and underwent controlled ambulatory pH moniterization and no reflux was detected.

Conclusion: In some cases this technique can be proposed to obese patients with GERD as a primary treatment modality. High numbers of patients and longer follow up care are needed to assess the long term efficacy and safety of this technique.

Keywords: Bariatric surgery; gastroesophageal reflux disease; Modified technique; Sleeve gastrectomy.

Ozan Şen, İsmail Çalıkoğlu, Görkem Özgen, Ahmet Gökhan Türkçapar, Mehmet Ali Yerdel. Sleeve gastrectomy in class 1 obesity: Assessment of operative outcomes. Surg Obes Relat Dis. 2021 Jan;17(1):170-176. DOI: 10.1016/j.soard.2020.08.014
https://pubmed.ncbi.nlm.nih.gov/32988747/

Abstract
Background: The risk/benefit ratio of sleeve gastrectomy (SG), especially in patients without type 2 diabetes (T2D), is unknown for patients with class 1 obesity.

Objectives: Assessment of operative outcomes of SG in class 1 obesity.

Setting: Private practice.

Methods: Candidates for a primary SG with body mass index 30-35 kg/m2 after 5 years of unsuccessful dieting were included after informed consent was obtained. Participants who did not complete 3-month follow-up and those who underwent modified SGs were excluded. Data and complications were recorded prospectively. Patients were followed up at 3, 6, and 12 months and yearly thereafter. Definition of presence and remission of T2D and insulin resistance were set according to guidelines. Effects on weight loss parameters were evaluated with Wilcoxon signed-rank test.

Results: Between 2012 and 2020, 143 consecutive SGs were performed in patients with class 1 obesity without conversion, leak, mortality, or a venous event. Two were lost to follow-up. In 141 participants, 2 bleedings and 1 colon perforation occurred (2.1% rate for acute life-threatening events). During a mean follow-up of 25.9 months; 1 case of functional stenosis and 4 cases of de novo symptomatic cholelithiasis clinically became evident in different patients, all requiring reoperation. Therefore a 5.6% rate of major complications were identified at 2 years. The benefit on weight loss was immediate and permanent (P < .001). T2D and insulin resistance were in remission in 100% and 98.1% of participants at 1 year, respectively.

Conclusion: The 5.6% major complication rate reflects a minimum because more de novo symptomatic gallstones and stenosis are yet to occur or overlooked. Additionally, this excludes patients with de novo reflux and malnutrition, dissatisfaction issues, or recidivism. Caution is required to freely operate on patients with class 1 obesity with no co-morbidity. Evidence-based outcome data are lacking to balance the reported risks.

Keywords: Adverse effect; Class 1 obesity; Complication; Sleeve gastrectomy.

Ozan Sen, Ahmet G. Turkcapar, Mehmet A. Yerdel. Screening Esophagogastroduodenoscopy Before Laparoscopic Sleeve Gastrectomy: Results in 819 Patients. J Laparoendosc Adv Surg Tech A. 2020 Sep 2 DOI: 10.1089/lap.2020.0541.
https://pubmed.ncbi.nlm.nih.gov/32882153/

Abstract
Aim: The routine use of esophagogastroduodenoscopy (EGD) during the preoperative evaluation of surgical weight loss candidates is controversial. The aim of this study is to evaluate the findings of preoperative EGD in patients who are scheduled for a primary laparosco

pic sleeve gastrectomy (LSG). The probable effect of these findings on the medical and surgical strategy that was followed is assessed.

Methods: Findings of EGD obtained from consecutive LSG candidates and all data were prospectively recorded and retrieved from the database.

Results: A total of 819 patients underwent EGD successfully. Mean age and body mass index were 38 ± 11.3 and 43.17 ± 7.2 kg/m2, respectively. Fifty-eight percent were female. EGD of 263 (32.1%) patients was normal and 687 (84%) patients were asymptomatic. At least one abnormal finding was detected in 65% of the asymptomatic patients. Abnormal findings that did not change the surgical strategy were found in 550 patients (67.2%). Findings such as gastritis or duodenitis that changed the medical management before surgery were found in 309 patients (38.2%). Helicobacter pylori was positive in 218 (26.6%) patients but eradication treatment was not applied in the preoperative period. No pathology was detected that would create absolute contraindication or change the type of surgery in any patient. Only technical modifications were required in 13% due to hiatal hernia. The timing of the planned surgery has changed in only 6 patients (0.74%) (early stage neuroendocrine tumor, leiomyoma, severe ulcer).

Conclusions: Routine EGD performed before LSG did not change the planned bariatric option in any patient, but led to 13% rate of technical modifications due to the presence of hiatal hernia. At least one abnormal finding was detected in 65% of asymptomatic patients. Due to endoscopic findings, the rate of patients who started medical acid-suppression treatment in the preoperative period was 38%.

Keywords: bariatric surgery; endoscopy; preoperative evaluation; sleeve gastrectomy. 

Ozan Şen, Hüseyin Ünübol, Ahmet G. Türkçapar, Mehmet A. Yerdel. Risk of Alcohol Use Disorder After Sleeve Gastrectomy. J Laparoendosc Adv Surg Tech A. 2021 Jan;31(1)24-28.
https://pubmed.ncbi.nlm.nih.gov/32525729/

Abstract
Aim: Several studies demonstrated increased alcohol intake after gastric bypass but not for laparoscopic sleeve gastrectomy (LSG). The purpose of this study is to determine whether there is an increased risk of developing alcohol use disorder after LSG.

Materials and Methods: LSG patients with at least 1-year follow-up who completed the alcohol use disorder identification test (AUDIT) preoperatively, and at their control visit, were the subjects. AUDIT was applied to the patients who were followed up from 1 to 6 years postoperatively. Patients were divided into two groups as those who were followed for 1-3 years and 4-6 years. AUDIT scores and risk categories were compared. According to the AUDIT results, score intervals between 0-7, 8-15, 16-19 and 20-40 identified patients with low, moderate, high risk, and alcoholism, respectively.

Results: There were 183 LSG patients eligible for inclusion. An AUDIT score of 2.79 before LSG showed prominent reduction in alcohol use in the first 3 years after LSG with a score of 2.27 (P = .033). At 4-6 years follow-up, AUDIT scores showed significant increase from 3.06 to 4.04, suggesting an increase in alcohol use in the long term (P = .042). In addition, the increase of risk after surgery in pre-LSG moderate-risk category (n = 21) turned out to be higher than pre-LSG low-risk category (n = 162).

Conclusions: This study showed reduction in AUDIT scores in the first 3-year follow-up after LSG and increase in the 4-6 years follow-up. High pre-LSG AUDIT score, a potential risk for future alcohol use disorder, was one of the key findings of our study. Screening of LSG candidates before and after surgery by AUDIT scoring according to risk categories with larger samples will provide useful input for relevant guidelines.

Keywords: alcohol use disorder; bariatric surgery; sleeve gastrectomy.

Ozan Sen, Ahmet G. Turkcapar. Hair Loss After Sleeve Gastrectomy and Effectiveness of Biotin Supplements. J Laparoendosc Adv Surg Tech A. 2021;31(3):296-300.
https://pubmed.ncbi.nlm.nih.gov/32762597/

Abstract
Aim: In this study, we aimed to determine the incidence of hair loss in patients who underwent laparoscopic sleeve gastrectomy (LSG), and to observe whether use of Bio has an impact on hair loss.

Methods: This study included 156 female patients who underwent LSG for obesity and completed a 1-year follow-up. All patients with vitamin deficiency were screened in the pre- and postoperative period. Hair loss was defined as the subjective perception of the women of losing a higher amount of hair when compared with normal situation.

Results: Hair loss was observed in 72% of the patients after LSG (n = 112). Seventy-nine percent of the patients reported hair loss between the third and fourth-month interval, and continued for an average of 5.5 ± 2.6 months. Permanent alopecia was not observed in any of the patients. Patients who experienced hair loss and Biotin deficiency after LSG were prescribed 1000 mcg/day of Biotin for

3 months. Of these 22 patients; only 5 (23%) patients reported a remarkable decline in hair loss. In addition, 29 patients were found to take 1000 mcg/day of Biotin for average 2.5 months after onset of hair loss by their own initiative, despite optimal blood Biotin levels. Eleven (38%) patients reported a remarkable decline in hair loss. The effect of biotin use on hair loss in patients with and without biotin deficiency was compared. There was no significant difference (P = .2).

Conclusion: Temporary hair loss after LSG is common. It was found that biotin supplementation used to prevent hair loss does provide low efficacy.

Keywords: bariatric surgery; biotin supplements; hair loss; sleeve gastrectomy.

Ozan Sen, Ahmet G. Turkcapar. Gastric botulinum toxin-A application for weight loss theraphy. The Turkish Journal of Gastroenterology 2020 August DOI: 10.5152/tjg.2020.20076
https://www.turkjgastroenterol.org/en/gastric-botulinum-toxin-a-application-for-weight-loss-therapy-136678

Abstract
Background/aims: The aim of this study is to share the results of gastric botulinum toxin (BTX) application in individuals who are overweight or type 1 obese without comorbidity.

Materials and methods: In this study, 13 patients were included who were enrolled for gastric BTX application for the first time. A total of 300 U of BTX-A (Allergan Botox ®1 vial 100 U) was diluted with 8 mL of 0.9% NaCl saline, and antrum (100 U to 8 spots), corpus (100 U to 8 spots), and fundus (100 U to 8 spots) regions were injected intramuscularly. Patients were given a 1200-calorie low-carb diet and this was followed for 6 months.

Results: Gastric BTX application was applied to 13 patients with a mean age of 40.9 ± 5.2 (85% female), a mean body mass index (BMI) of 28.41 ± 1.4 kg/m2 (26-31.6) and a mean excess weight of 10.1 ± 3.6 kg. As a result of the 6-month follow-up, only four patients (30.8%) were able to lose more than 50% of their excess weight (6-15 kg). Six patients (46.2%) could not lose any weight. There was an average decrease of 3.3 kg in the weight of patients before and after BTX application (P = .03). A mean decrease of BMI was detected, 1.17 kg/m2 (P = .032).

Conclusion: It was concluded that the application of gastric BTX for weight loss does not provide effective results.

Ozan Sen, Fatih Can Karaca, Ahmet G. Turkcapar. Neurological Complication After Laparoscopic Sleeve Gastrectomy: Foot Drop. Obesity Surgery 2020 Mar;30(3):957-960
https://pubmed.ncbi.nlm.nih.gov/31741213/

Abstract
Background: The relationship between rapid weight loss and peroneal nerve entrapment neuropathy (PNEN) was shown in various series following bariatric surgery. Thus, we aimed to determine the occurrence of PNEN in our patients who underwent laparoscopic sleeve gastrectomy (LSG) and to reveal the factors contributing to this complication.

We evaluated our series of 35 patients in terms of surgery: following laparoscopic sleeve gastrectomy, retrospectively. We recorded the preoperative data, laboratory vitamin and nutrient levels, weight loss, electromyography (EMG) findings, and treatment modalities of these patients.

Results: Seven out of 635 patients developed foot drop as a result of PNEN after bariatric surgery. The mean total weight loss for these patients was 50.6 kg in 6 months, and 63 kg in 12 months. In the laboratory analyzes, we did not detect any signs of vitamin deficiency. EMG findings confirmed the diagnosis.

Conclusion: We demonstrate that rapid weight loss is correlated with the risk of foot drop incidence as a result of PNEN.

Keywords: Bariatric surgery; drop foot; Neurological complications; weight loss.

Ozan Sen, Ahmet G. Turkcapar, Mehmet A. Yerdel. Cholelithiasis After Sleeve Gastrectomy and Effectiveness of Ursodeoxycholic Acid Treatment. J Laparoendosc Adv Surg Tech A. 2020 Nov;30(11):1150-1152.
https://pubmed.ncbi.nlm.nih.gov/32228343/

Abstract
Aim: Few adverse effects may occur after bariatric surgery, one being the formation of gallstones. The aim of this study is to determine the incidence of cholelithiasis after laparoscopic sleeve gastrectomy (LSG) and whether ursodeoxycholic acid (UDCA) treatment reduces gallstone formation.

Materials and Methods: Gall bladders of all patients planned for LSG were preoperatively checked by ultrasonography (USG). Patients who had no documented gallbladder pathology before LSG and who had USG at 12th month and 2 years follow-up after LSG were included in the study. The incidences of newly developed cholelithiasis, cholecystectomy, and endoscopic retrograde cholangiopancreatography (ERCP) requirement in patients who did not receive any UDCA treatment (pre-2015 protocol, n=128) was compared with the corresponding numbers in patients who regularly used 500 mg/ day oral UDCA for 6 months after the LSG (post-2015 protocol, n = 152).

Results: Between January 2012 and October 2018, 717 LSGs were performed in two centers and after exclusions, 280 paws

ents were eligible for evaluation. Sixty-four of 280 (23%) patients developed cholelithiasis after LSG and cholecystectomy was performed in 24 patients (8.6%) for symptomatic cholelithiasis. In the non-UDCA group, 48 patients developed cholelithiasis (n = 48/128, 37.5%) compared with 16 patients in the UDCA group (n = 16/152, 10.5%) (P< .001). Compared with 5 patients in the UDCA group, 19 patients undergone cholecystectomy (39.6%) in the non-UDCA group due to symptomatic cholelithiasis (P = .55) and 5 of these patients also required an ERCP. No ERCP became necessary in the UDCA group (P = .2).

Conclusions: An almost fourfold decrease in the rate of new gall stone formation with 500 mg daily UDCA treatment was impressive and may suggest routine UDCA treatment after LSG. Given the rate of exclusions and follow-up differences among the groups, certainly, randomized trials, with less exclusion are needed to provide conclusive evidence.

Keywords: cholelithiasis; sleeve gastrectomy; ursodeoxycholic acid; weight loss.

Ozan Şen, İsmail Çalıkoğlu, Görkem Özgen, Toygar Toydemir, Ahmet Gökhan Türkçapar, Mehmet Ali Yerdel. Sleeve Gastrectomy in patients with previous anti-reflux surgery. Preliminary results of the '' no-touch to posterior wrap'' technique. Surgery For Obesity And Related Disease. 2019;15(10):1668-74
https://pubmed.ncbi.nlm.nih.gov/31521563/

Abstract
Background: Reported morbidity of Roux-en-Y gastric bypass in patients with previous antireflux surgery warrants caution, and data on sleeve gastrectomy (SG) are unexpectedly scarce.

Objectives: To evaluate the safety and efficiency of SG in patients who previously underwent an antireflux procedure. A new technique to preserve intact fundoplication is described.

Setting: Private practice, bariatric center of excellence, Turkey.

Methods: The following data were retrieved from our prospective data base: (1) details of previous repair; (2) clinical/endoscopic reflux status, body mass index (kg/m2), and presence of metabolic syndrome (MetS) and type 2 diabetes (T2D) before SG; (3) duration of SG, length of stay, complications; and (4) percent excess weight loss, MetS/T2D resolution, and reflux status at follow-up.

Results: Fifteen consecutive SGs were performed without conversion or major complications. The first case is excluded from the analysis because complete wrap unfolding was abandoned in favor of the described technique. Among 14, 10 had MetS, 4 had T2D, and 1 had a proven reflux recurrence before SG. Mean operating time was 118.5 minutes. All were discharged on the third postoperative day. Apart from 1 functional stenosis, no complications occurred. At 12 months, percent excess weight loss rate was 82.2, MetS resolved in 9 of 10, and T2D was in complete (n = 2) or partial remission (n = 1). No de novo reflux became evident, and absence of reflux was proved by pHmeter in 3.

Conclusions: SG is feasible in patients who previously had antireflux repair with negligible morbidity and percent excess weight loss rates similar to that with regular sleeves. Results in reflux control needs further confirmation.

Keywords: Antirreflux surgery; Nissen; Sleeve gastrectomy; Toupet

Ozan Sen, Ahmet Turkcapar. Finding carcinoid tumor before bariatric surgery. Is preoperative endoscopy necessary? case report. International Journal of Surgery Case Reports. 2019; 62:132-134
https://www.sciencedirect.com/science/article/pii/S2210261219304742?via%3Dihub

Abstract
Introduction: Carcinoid tumors are endocrine system-related lesions and 4% of the gastrointestinal tract's neuroendocrine tumors (NET) originate from stomach. In recent years, gastric carcinoid tumors have been reported at increasing rates on endoscopies. In this article, we will present a case of gastric carcinoid tumor detected at the upper gastrointestinal (GI) endoscopy during preoperative bariatric surgery workup.

Case presentation: A 55 years old male patient with body mass index (BMI) 46 kg/m2 was scheduled for bariatric surgery. Upper GI endoscopy revealed 2 separate 4-5 mm nodular lesions at gastric corpus and antrum. Biopsies were taken and both lesions were reported as neuroendocrine tumors. It was decided that the Laparoscopic sleeve gastrectomy (LSG) operation would be performed because both lesion areas would remain in the extracted part of stomach.

Discussion: The routine use of upper GI endoscopy in preoperative evaluation of bariatric surgery patients still remains controversial.

Conclusion: Upper GI endoscopy is very important in determining various gastric pathologies and determining the most appropriate surgical method before bariatric surgery.

Keywords: Bariatric surgery; Neuroendocrine tumor; Preoperative endoscopy.

Ozan Sen, Ahmet Gokhan Turkcapar, Mehmet Ali Yerdel. The effects of sleeve gastrectomy on shoe size one year after surgery. Turk J Surg 2017; 33:284-87
https://turkjsurg.com/abstract/1457/eng

Abstract
Objective: The aim of this study is to evaluate the effects of

sleeve gastrectomy on shoe size one year after the procedure. To our knowledge, no study has yet been conducted addressing this issue.

Material and Methods: Patients who were prepared for sleeve gastrectomy were eligible for the study, and all data and preoperative shoe sizes were recorded in our prospective database. At the 12th month of follow-up, each patient's excess weight loss % was calculated, and their shoe sizes were recorded by verbal report. Arbitrary or half-size changes were not taken into consideration. The probability of a change in shoe size and the effects of age, sex, preoperative body mass index, and 12th month excess weight loss % on this change were investigated. p<0.05 was considered as statistically significant.

Results: The subjects of the study were 212 patients who completed their 12-month follow-ups after sleeve gastrectomy between January 2012 and February 2016. The mean shoe size was 41.5; this decreased to 40.5 one year after sleeve gastrectomy (p<0.001). In patients with body mass index (BMI)>50, both the mean decrease (p=0.008) and the percentage of at least two size decreases (p=0.009) were significantly higher than those in patients with BMI<40. Age, sex, and excess weight loss % did not have any significant effects on shoe size.

Conclusion: Sleeve gastrectomy was clearly associated with decrease in shoe size after 12 months. Only preoperative body mass index was found to be directly associated with this decrease.

Keywords: Bariatric surgery, sleeve gastrectomy, shoe size

Mehmet Ali Yerdel, Ozan Sen, Utku Zor, Simay Kara, Bulent Acunaş. Cardiac Tamponade as a Life- Thereating Complication of Laparoscopic Antireflux Surgery: The Real Incidence and 3D Anatomy of a Heart Injury by Helical Tacks. Journal Of Laparoendoscopic &Advanced Surgical Techniques 2018 Sep;28(9): 1041-1046
https://pubmed.ncbi.nlm.nih.gov/29493372/

Abstract
Background: Cardiac tamponade (CT) is a dreadful complication of laparoscopic antireflux surgery (LARS) with unknown incidence, and preventive measures are yet to be defined. Incidence during LARS with respect to usage/configuration of graft deployment is analyzed. Three-dimensional (3D) analysis of tack distribution provided anatomical insight to prevent cardiac injury.

Materials and methods: Data regarding the usage and configuration of graft deployment are retrieved from the prospective database. Grafting was “posterior” or “posterior + anterior.” Incidence of CT in all hiatoplasty is calculated. Tomography is reconstructed in 3D, showing the spatial distribution of the tacks. Tacks are numbered in the surgical video. Corresponding numbering is applied to the tacks in any particular tomography slice, utilizing the 3D images as an interface. A numbering-blinded radiologist is asked to identify the offending and the nonoffending tacks as the cause of tamponade. Tack-to-pericardium distances are recorded. Tacks having no measurable distance from the pericardium are considered offensive.

Results: One CT occurred in 1302 consecutive LARS (0.076%). The incidence is 0% when “no” (379) or “posterior” (880) graft is used as opposed to 2.3% rate in “posterior + anterior” (43) grafting. The distribution of “offensive,” “nonoffensive but nearest,” and “safe” tacks followed a pattern. All offensive tacks belonged to the anterior graft fixation, which we referred as the critical zone.

Conclusion: CT during LARS is rare, and associated with graft fixation anterior to the hiatal opening. Avoiding graft fixation to the critical zone may prevent cardiac injury.

Keywords: cardiac tamponade; complication; helical tack; laparoscopic antireflux surgery.

Soyder, M. Ünübol, O. Şen, S. Özbaş, S. Koçak. The predictive value of the clinical features of malignancy in cases of preoperative follicular throid neoplasia. Minerva Chir 2012;67:475-80
https://pubmed.ncbi.nlm.nih.gov/23334110/

Abstract

Aim: It is generally impossible to make a distinction between benign and malignant with a cytopathological examination using a fine needle aspiration biopsy (FNAB) in follicular lesions of the thyroid gland. This is the reason why lesions are frequently reported as follicular neoplasia (FN). Our study aims to examine the predictive value of carcinoma detection of different clinical features in cases with determined FN with FNAB.

Methods: Clinical and histopathological data of a total of 116 patients (26 male, 90 female) subjected to surgery because of thyroid gland pathology with FN between March 1997 and December 2011 were retrospectively examined in two different centers.

Results: Results of the histopathological examinations were reported as: carcinoma in 33 (28.4%) cases (18 [54.5%] cases with papillary thyroid cancer, 11 [33.3%] cases with follicular thyroid cancer and 4 [12.1%] cases with papillary thyroid cancer follicular variant), as follicular adenoma (FA) in 32 (27.6%) patients and as a benign colloidal nodule in 51 (43.9%) patients. No statistical significanc

e was determined between advanced age, male sex, solid single nodule, increased nodule diameter, hypoactive nodule existence and malignancy (P>0.05).

Conclusion: Malignancy was found in 28.4% cases with FN detected as a result of FNAB in our study series, a ratio which is significantly higher than that reported in the literature. We think that the characteristics of the patient and the tumor are not effective in diagnosing cancer. In the case of the existence of bilateral thyroid pathology, the surgical therapy option should be bilateral total thyroidectomy due to such a high ratio of cancer occurrence.

Articles Published in National Journals
Ozan Sen, Ayhan Kuzu. Our Colonoscopic Screening Results According to Risk Groups in Colorectal Cancers (Pilot Study). Turkish Journal of Colorectal Disease. 2020; 30:42-48
https://cms.galenos.com.tr/Uploads/Article_36580/turkishjcrd-30-42-En.pdf

Abstract

Aim: Most of the colorectal cancers develop on a pre-existing polyp background. With the widespread use of screening tests, mortality of colorectal cancers has been shown to decrease. Our aim in this pilot study is to screen individuals according to risk groups in colorectal cancers and to obtain data that will lead in the establishment of community-based information and screening programs in this direction.

Method: Between October 2004 and February 2008, 358 people underwent colonoscopy for the purpose of screening. Individuals who had a family history of colorectal cancer or polyp, who had a history of colorectal polyps, and who were over the age of 40 years and wanted to voluntarily participate in the screening program although there were no risk factors were classified as average, low , medium and high risk groups. Individuals with a history of colorectal cancer and inflammatory bowel disease were excluded from the study.

Results: As a result of the screening, polyps were detected in 104 (29.1%) people, and masses with malignant appearance in 9 (2.5%) people. Histopathological evaluation revealed adenomatous polyp in 67 (18.7%) individuals, inflammatory polyp in 26 (7.3%) patients, malignant polyp in 11 (3.1%) patients, and invasive cancer in 9 (2.5%) patients (n=358).

Conclusion: Although the results of this pilot study do not reflect the whole society, the frequency of colorectal polyp and cancer is high in our country. In colorectal cancers, it is possible to cure the disease curatively with screening and early diagnosis before the development of cancer. In this regard, the society should be made more conscious and screening programs should be expanded.

Keywords: Colorectal cancers, screening, pilot study, colonoscopy

Ozan Sen, Fatma Kahraman, Ahmet Gokhan Turkcapar. The Role of Surgery in Patients with Body Mass Index between 30-35. Turkiye Klinikleri J Gen Surg-Special Topics 2015;8(3)
https://www.turkiyeklinikleri.com/article/tr-beden-kitle-indeksi-30-35-arasi-hastalarda-cerrahinin-yeri-72849.html

SUMMARY
Obesity is a very common health problem in all societies and is increasingly becoming a global epidemic. Body Mass Index (BMI) criteria were first proposed and accepted at the National Institute of Health (NIH) conference in 1991 as a measure of bariatric surgery. Since then, a lot of scientific data has been accumulated on the benefits and risks of bariatric surgery. It was seen that; The benefit after bariatric surgery is not just weight loss. In this respect, the rejection of bariatric surgery in a stage I obese patient based on BMI alone does not seem correct. Non-surgical methods should be the primary choice in the treatment algorithm of stage I obesity. If non-surgical applications are insufficient, bariatric surgery should definitely be considered. The International Diabetes Federation (IDF) has defined surgical treatment as "an alternative treatment option that should be considered" in patients with BMI < 35 kg/m2 who do not respond to medical treatment. Recently, the International Society for Obesity and Metabolic Surgery (IFSO) agreed on a 10-item recommendation on the safety and efficacy of surgical treatment of stage I obesity.

Keywords: Obesity; body mass index; obesity surgery

ABSTRACT
Obesity is a health problem commonly seen in all nations and it is getting a worldwide epidemic. The body mass index (BMI) criteria for bariatric surgery as proposed in 1991 by the National Institute of Health Conference Panel(NIH) initially worked well. Since then, a lot of scientific data cumulated about bariatric surgery, it's benefits and risks. And it is seen that the benefit of bariatric surgery is not just weight loss. By this aspect, refusing surgery of a class I obesity patient regarding to his BMI is not considered right. Nonsurgical therapy should be the first choice in the treatment plan but in case of inadequacy, bariatric surgery must be considered. International Diabetes Federation (IDF), is mentioned that bariatric surgery is “a type of treatment option which

should take in to consideration which will apply to patients with BMI < 35 and resistance to medical therapy.” And recently, International Federation for Surgery of Obesity and Metabolic Disorders (IFSO) build consensus including 10 items about effectiveness and safety of surgery treatment of class I obesity.

Keywords: Obesity; body mass index; bariatric surgery

Ozan Şen, A. Bülent Erkek, Atıl Çakmak, Ulaş Sözener, Cihangir Akyol, M. Ayhan Kuzu. Internet use of general surgery patients and their relatives in search of information. Turk J Surg 2008;24(3):156-59
https://turkjsurg.com/full-text/728/tur

Summary
Aim:
In this study; In this study, it was aimed to reveal the frequency of internet use of inpatients in a clinic and their relatives in order to obtain information about their diseases.

Materials and Methods:
A total of 1400 people, 700 of whom were patients and 700 of their relatives, were asked to fill out a questionnaire prepared to determine the frequency of internet use and their socio-demographic characteristics.

Results:
Of the study participants, 673 (48%) were male, 727 (52%) were female, and their ages ranged from 16 to 75 (median, 52 years). In terms of education level, 657 (46.9%) people had high school and above, 743 (53.1) people had secondary school and below. It was determined that 504 (36%) of the people who participated in the survey had a computer at home, and 418 (29.8%) people used the internet in their daily lives. Considering the internet usage rates by education level, it was found that 385 (27.5%) people at high school and higher education level, and 33 (2.3%) people at secondary school and below education level use the internet in their daily lives. When we look at the frequency of internet use in order to obtain information about the diseases of patients and their relatives, it was found that 234 (16.7%) people made research on the internet, and only 109 (7.7%) of them could reach sufficient Turkish resources about their diseases. There was a health website that 65 (4.6%) people followed regularly on the internet.

Conclusion:
It was determined that the frequency of internet use in the search for information related to the diseases of the patients and their relatives participating in this study was significantly low. There is a need for diligent studies for a conscious society that takes care of their health in this regard. In order to ensure that patients and their relatives can easily access accurate, understandable and up-to-date information, health units use these resources. must be closely related.

Keywords: General Surgery patients, Internet, Health information

Ozan Sen, Ahmet Gokhan Turkcapar. Partial and Total Fundoplication Methods, Effect of Surgical Technique on Postoperative Complications and Relapses. Turkey Clinics J Surg- Special Topics 2017;10(3):189-93
https://www.turkiyeklinikleri.com/article/tr-parsyel-ve-total-fundoplikasyon-yontemleri-cerrahi-teknigin-postoperation-komplikasyon-ve-nukslere-etkisi-79925.html

SUMMARY
Laparoscopic anti-reflux surgery is the gold standard treatment option for the surgical treatment of gastroesophageal reflux disease. Although the effect of laparoscopic nissen fundoplication on reflux control is well known, postoperative dysphagia and gas-related functional side effects are common. For this reason, the original technique has undergone modifications over time and alternative techniques have emerged. The best known of these is the partial fundoplication technique described by Andrea Toupet in 1963. While the debate on the most ideal method in anti-reflux surgery continues even today, the chosen method should provide effective and long-term reflux control, and postoperative dysphagia and gas-related symptoms should be minimal. Many comparative studies in recent years have shown that laparoscopic nissen fundoplication (LNF) and laparoscopic toupet fundoplication (LTF) have similar effects in providing reflux control. On the other hand, functional side effects associated with post-operative dysphagia and gas are more common after LNF. These complications can be minimized with LTF.

Keywords: Gastroesophageal reflux; fundoplication; undesirable effects; recurrence

ABSTRACT
Laparoscopic anti reflux surgery is a gold standard for surgical treatment of gastroesophageal reflux disease. Although the effect of laparoscopic nissen fundoplication on reflux control is well known, postoperative dysphagia and gas related functional side effects are widely observed. Therefore, the original techniques have been modified over time and alternative techniques have emerged. One of all is well known that partial fundoplication technique was defined by Andrea Toupet in 1963. However the debate about the ideal method of anti-reflux surgery continues even today, the selected method should be effective and provide reflux control for long term and postoperative dysphagia and gas releated symptoms should be minimal. According to recent comparative studies shown that laparoscopic nissen fundoplication (LNF) and laparoscopic toupet fundoplication (LTF) have similar effect on providing reflux

control. Whereas, postoperative dysphagia and gas related functional side effects are more common after LNF. These complications can be minimized with LTF.

Keywords: Gastroesophageal reflux; fundoplication; adverse effects; recurrence

Ozan Sen, Ahmet Gokhan Turkcapar. Revision Anti Reflux Surgery. Turkiye Klinikleri J Surg Special Topics 2017:10(39:202-6
https://www.turkiyeklinikleri.com/article/en-revizyon-anti-reflu-cerrahisi-79927.html

SUMMARY
Laparoscopic anti-reflux surgery has become the gold standard in the surgical treatment of gastroesophageal reflux disease. However, recurrence after surgery is still an important problem. In some patients, revision surgery may be required due to persistent symptoms. The main symptoms in patients requiring revision surgery are recurrent reflux and dysphagia. Revisional anti-reflux surgery is a very difficult operation compared to the first operation, and in this respect, these patients should be carefully evaluated in the preoperative period. It is important to obtain objective evidence for this in patients with reflux symptoms. Esophagogastroduodenoscopy, radiological passage imaging and pH monitoring should be performed. In the reported series, the most common intraoperative finding during revision surgery was found to be transhiatal herniation of fundoplication. Compared to primary surgery, revisional anti-reflux surgery has higher morbidity, mortality and complication rates and lower patient satisfaction symptomatically. In this respect, revision surgery should be considered in patients with significant dysphagia or whose symptoms do not regress despite medical treatment. Laparoscopic revisional anti-reflux surgery should be performed by surgeons experienced in this field.

Keywords: Gastroesophageal reflux; fundoplication; recurrence; reoperation

ABSTRACT
Laparoscopic anti reflux surgery has been gold standard method for the surgical treatment of gastroesophageal reflux disease. However, recurrence after surgery is still an important problem. Revision surgery may be needed because of intractable symptoms of some patients. The main symptoms of patients who need revision surgery are recurrent reflux and dysphagia. Revisional anti-reflux surgery is a very difficult operation compared to the first operation and therefore it is necessary to evaluate these peitents carefully in preoperative period. Hence, it is important to obtain objective evidence of patients who have reflux symptoms. Esophagogastroduodenoscopy, radiological passage screening and pH monitoring should be performed. In the reported series, it was detected that the most commonly intraoperative finding in the revision surgery is transhiatal herniation of the fundoplication. Compared with primary surgery, revision anti-reflux surgery is associated with higher morbidity, mortality, complication rates and patient satisfaction is lower in terms of symptoms. In this respect, revision surgery should be considered in patients who have significant dysphagia or whose symptoms can not be improved despite medical treatment. Laparoscopic revision anti-reflex surgery should be performed by experienced surgeons in this field.

Keywords: Gastroesophageal reflux; fundoplication; recurrence; reoperation

Cihangir Akyol, Atıl Cakmak, Ilknur Kepenekci, Ozan Sen, Seher Demirer. Metaplastic Breast Carcinoma: A Rare Tumor. Journal of Breast Health 2008;4:2
https://cms.galenos.com.tr/Uploads/Article_42634/ejbh-4-127-En.pdf

SUMMARY

Metaplastic carcinoma of the breast is a rare high-grade lesion, accounting for less than 1% of all malignant breast lesions. This term (metaplastic breast carcinoma) was first used by Huvos et al. in 1974. It has a worse prognosis and aggressive course compared to other breast cancers. Metaplastic carcinoma of the breast is a general term describing the heterogeneous group that includes biphasic lesions with malignant epithelial and malignant mesenchymal tissue components together.

In this article, a case of metaplastic carcinoma of the breast in a 51-year-old female patient is presented. A modified radical mastectomy was applied to the patient who presented with a mass in the right breast that gradually increased in size, following frozen examination. Histopathological examination revealed T2N1bII, Grade III, ER(-), PR(-), cerbB2 (-) metaplastic breast carcinoma. The patient, who received adjuvant chemotherapy, is followed up without recurrence in the 22nd postoperative month.

Key words: metaplastic breast carcinoma, carcinosarcoma, myoepithelial cells.

ABSTRACT

Metaplastic carcinoma of the breast (MCB) is rare type of breast cancer counting for < 1% of breast malignancies. The term metaplastic carcinoma was first introduced by Huvos et al. MCB is an aggressive disease and has poor prognosis. MCB denotes a heterogeneous group of uncommon malignant entities. Conventionally the term is used to denote tumors with mixed malignant epithelial and malignant mese

nchymal components.

We report a case of MCB in 51 years old women. She has presented with pal- pable and progressively enlarging mass in the right breast. Modified radical mastectomy was performed. Histopathologic diagnosis was reported as T2N1bII, Grade III, ER (-), PR (-), cerbB2 (-) metaplastic breast carcinoma. Adjuvant che- motheraphy was performed. Recurrence has not been detected at 22 months after surgery.

Key words: metaplastic carcinoma of the breast, carcinosarcoma, myoepithelial cells.

Written National / International books or chapters in books.
1. Brian P. Jacobs, Bruce Ramshaw. SAGES Hernia Repair Handbook Nobel Medical Publications Ahmet Türkçapar, Ozan Şen (Book Section)

2. Ozan Sen, Ahmet Turkcapar. Recurrent Dysphagia After Heller Myotomy. Achalasia: Current diagnostic and therapeutic approaches, 1st Edition. Turkiye Klinikleri 2019. P.65-9 (Book Chapter)

Studies presented as papers in international and national scientific meetings
1. Atıl Çakmak, Akın Fırat Kocaay, Cihangir Akyol, Erkin Orazakunov, Marlen Sulamaniov, İlknur Kepenekçi, Volkan Genç, Ozan Şen, Bülent Erkek, Selçuk Hzinedaroğlu. 5mm Throchar site fistula formation due to gallstone; Late and rare complication of laparoscopic cholecystectomy. 2008 Sugical Infection Society Europe 21st Annual Congress Antalya

2. Ozan Şen, Ahmet Gökhan Türkçapar, Fatma Kahraman, Eldem Erdem, Toygar Toydemir, Selma Bekir, Mehmet Ali Yerdel. Colonoscopic Screening Before Bariatric Surgery. 4th National & 1st Mediterranean Congress on Surgery for Morbid Obesity and Metabolic Disorders October 2015 Antalya

3. Ozan Şen, Ahmet Gökhan Türkçapar, Fatma Kahraman, Eldem Erdem, Selma Bekir, Mehmet Ali Yerdel. Leakage after stenosis after sleeve gastrectomy: a case report 4th National & 1st Mediterranean Congress on Surgery for Morbid Obesity and Metabolic Disorders October 2015 Antalya

4. Ozan Sen, Ahmet G. Turkcapar. Combined partial posterior fundoplication with laparoscopic sleeve gastrectomy for morbid obese patients with symptomatic GERD. ASMBS 2021 annual meeting

5. O. Sen, A. B. Male, U. Sözener, M.A. Lamb. Internet Usage of General Surgery Patients in Search of Information S-274 National Surgery Congress 2006 Antalya

6. Cumhur Özcan, Mehmet Akif Türkoğlu, Ozan Şen, Cüneyt Köksoy, Uğur Bengisun. Thrombolytic therapy experience in acute vascular thrombosis. 13th National Vascular Surgery Congress 2007

7. Mehmet Akif Türkoğlu, Cumhur Özcan, Ozan Şen, Cüneyt Köksoy, Uğur Bengisun. Our Endovascular Experiences in Aortoiliac and Infrainguinal Atherosclerotic Occlusions and Stenoses. 13th National Vascular Surgery Congress 2007

8. Mehmet Akif Türkoğlu, Cumhur Özcan, Ozan Şen, İskender Alaçayır, Uğur Bengisun. Our EVAR Experiences. 13th National Vascular Surgery Congress 2007

9. Ozan Sen, Mehmet Akif Turkoglu, Cumhur Ozcan, Cüneyt Köksoy, Uğur Bengisun. Vena Cava Filters in Venous Thromboembolism. 13. National Vascular Surgery Congress 2007 Antalya

10. O. Şen, A.B Male, L.T. Şenol, H. Zeybek, P. Çakır, M.A. Lamb. Screening in Colorectal Cancers (Pilot Study) Kol-25 National Surgery Congress 2008 Antalya

11. E. Orozakunov, A. Çakmak, V. Genç, D. Balcı, G. Bora, O. Şen, S. Treasurydaroğlu. Laparoscopic Donor Nephrectomy: Is It Applicable in Our Country? National Surgery Congress 2008 Antalya

12. A. Cakmak, O. Sen, C. Akyol, I. Kepenekci, E. Anadol. Ectopically Localized Gallbladder In The Falciform Ligament: A Case Report. National Surgery Congress 2008 Antalya

13. V. Genç, A. Çakmak, G. Aylaz, D. Balcı, İ. Kepenekci, O. Sen, M. Gurel. Isolated Splenic Etastasis of Colon Cancer: A Case Report. National Surgery Congress 2008 Antalya

14. C. Akyol, G. Bora, A. Çakmak, O. Şen, G. Aylaz, V. Genç, C. Bumin. Anorectal Malignant Melanoma: A Case Report. National Surgery Congress 2008 Antalya

15. M. Ali Yerdel, Ahmet Türkçapar, Ozan Şen. Course: Applied Sleeve Surgery 7th National Endocrine Surgery Congress 2013 Antalya

16. M. Ali Yerdel, Ahmet Türkçapar, Ozan Şen. Course: 2-day practical Bariatric Surgery course for general surgeons Istanbul bariatrics Obesity Center October 2014

17. Ozan Şen, Ahmet Gökhan Türkçapar, Fatma Kahraman, Mehmet Ali Yerdel. The effect of "full-thickness" suturing of the stapler patient by embedding the upper corner on sleeve complications. 12. National Endoscopic Laparoscopic Surgery Congress 2015

18. Ozan Şen, Ahmet Gökhan Türkçapar, Fatma Kahraman, Mehmet Ali Yerdel. Intraoperative Problems in Laparoscopic Sleeve Gastrectomy. 12. National Endoscopic Laparoscopic Surgery Congress 2015

19. Ozan Şen, Ahmet Gökhan Türkçapar, Fatma Kahraman, Eldem Erdem, Toygar Toydemir, Selma Bekir, Mehmet Ali Yerdel. Do Feet Shrink After Bariatric Surgery? Eur JSurg Sci 2015;6(Suppl 1):1-29

20. Ozan Şen, Ahmet Gökhan Türkçapar, Fatma Kahraman, Eldem Erdem, Selma Bekir, Mehmet Ali Yerdel. Istanbul Bariatrics "Our Experience with 337 Cases" Eur JSurg Sci 2015;6(Suppl 1):1-29

21. Ozan Şen, Ahmet Gökhan Türkçapar, Mehmet Ali Yerdel. A Rare Complication After Bariatric Surgery: Drop Foot (Peroneal Trap Neuropathy). 13. National E

Endoscopic Laparoscopic Surgery Congress 2017

22. Ozan Şen, Ahmet Gökhan Türkçapar, Mehmet Ali Yerdel. Gastric Carcinoid Tumor Detected Before Bariatric Surgery. 13. National Endoscopic Laparoscopic Surgery Congress 2017

23. Ozan Sen. Is Preoperative Endoscopy Necessary in Sleeve Gastrectomy? Obesity and Metabolic Surgery Platform Video Symposium 2017 Istanbul

24. Ozan Şen, Ahmet Gökhan Türkçapar, Mehmet Ali Yerdel. Laparoscopic Sleeve Gastrectomy After Previous Antireflux Surgery. 14th National Endoscopic Laparoscopic Surgery Congress joint with MMESA Spring meeting 2019 Cyprus

25. Ozan Sen, Ahmet Gokhan Turkcapar. Barret's Ulcer 5 Years After Sleeve Gastrectomy. 14th National Endoscopic Laparoscopic Surgery Congress joint with MMESA Spring meeting 2019 Cyprus

26. Ozan Şen, Ahmet Gökhan Türkçapar, Mehmet Ali Yerdel. Nasogastric Tube Stapling During Sleeve gastrectomy. 14th National Endoscopic Laparoscopic Surgery Congress joint with MMESA Spring meeting 2019 Cyprus

27. Ozan Sen, Ahmet Gokhan Turkcapar. Unusual treatment method in a patient who developed pneumothorax in laparoscopic recurrent hiatal hernia surgery. 7. National Hernia Congress. 3-6 October 2019 Izmir

28. Ozan Sen, Fatih Can Karaca, Ahmet Gokhan Turkcapar. Laparoscopic repair of recurrent hiatal hernia and anterior abdominal wall hernia after open hiatal hernia surgery. 7. National Hernia Congress. 3-6 October 2019 Izmir

29. Ozan Sen, Ahmet Gokhan Turkcapar. Anestesia awereness during bariatric surgery. 6th National 5th Mediterranean Congress of Morbid Obesity and Metabolic Diseases 17-20 October 2019 Antalya

30. Ozan Şen, Fatih Can Karaca, Ahmet Gökhan Türkçapar. Gastroesophageal reflux disease after sleeve gastrectomy. The prevalence and effectiveness of technical modifications. 3. Bariatric and Metabolic Surgery Congress 21-24 November 2019 Antalya

31. Ozan Sen, Ahmet Gokhan Turkcapar. Endoscopic botox application in obesity treatment. Is it an effective method? 10. National Obesity Congress 20-23 November Istanbul

32. Ozan Sen. Can gallstone formation be prevented after bariatric surgery? Turkish Obesity Surgery Association 5th Winter School 2021

33. Ozan Sen. The Effect of Obesity and Obesity Surgery on Women's Health in Women in Our Country. 4th International Nutrition, Obesity and Community Health Congress. 2020. Istanbul

34. Ozan Sen. The Effect of Low-calorie Diet Applied Before Bariatric Surgery on Postoperative Weight Loss. 9th National Healthy Living E-Congress 2020

35. Ozan Sen. Is Cholecystectomy Necessary in the Same Session in Morbial Obese Patients with Asymptomatic Cholelithiasis who Are Planned for Laparoscopic Sleeve Gastrectomy Surgery? University of Health Sciences 4th Gastroenterology Days 2020

36. Ozan Sen. Collaboration and Publication Culture. Invited speaker. 6th National and 5th Mediterranean Metabolic Diseases Congress 2019 Antalya

37. Ozan Sen. Nightmare in the Operating Room. Invited speaker. 6th National and 5th Mediterranean Metabolic Diseases Congress 2019 Antalya

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