COMPARATIVE STUDY BETWEEN SLEEVE GASTRECTOMY WITH SINGLE ANASTOMOSIS DUODENO-ILEAL BYPASS AND MINI-GASTRIC BYPASS IN MANAGEMENT OF MORBID OBESITY.

Background: Many surgical procedures have been proposed for management of morbid obesity. This study was conducted aiming to compare between the outcomes of open loop duodenal switch (DS) and laparoscopic minigastric bypass (MGB) procedures. Study type: Prospective comparative study. Patient and methods: 50 patients were included in the study. They were divided into 2 groups; group 1 included 25 patients who underwent open loop DS while group 2 included 25 patients who underwent laparoscopic minigastric bypass. All patients were subjected to complete history taking, physical examination, and routine investigations. Lipid profile and diabetic status were also assessed. After discharge, patients were followed up at 3, 6, and 12 months after the procedures where weight, BMI, and laboratory investigations were assessed in each visit. Results: The mean age of the included patients was 34.76 for the DS group and 36.0 years for MGB group. In each group, 20 females (80%) as well as 5 males (20%) were included. The mean BMI of the included patients was 52.59 and 51.6

Multiple medical and surgical ways have been proposed to treat obesity. Medical methods include exercise, diet, as well as some medications like phentermine and more recently combination drugs containing phentermine and topiramate. Nevertheless, these options achieve modest weight loss and are difficult to sustain over the long term. Conversely, bariatric surgery can achieve sustained and more effective weight loss. In addition, it leads to resolution of many obesity related comorbidities 5 As it achieves better short and long term results, bariatric surgical procedures are considered the best current treatment option for severe obesity 6 .
Being a modification of the biliopancreatic diversion procedure originally described by Scopinaro, duodenal switch (DS) is a bariatric procedure that depends mainly on malabsorption. The main differences between the two procedures are preservation of the pylorus, sleeve gastrectomy (SG) to reduce the gastric reservoir, and a common channel with a length of 100 cm rather than 50 cm as described originally by Scopinaro 7 . Food absorption is decreased by the diversion of biliopancreatic secretions in this procedure. In addition, rapid delivery of nutrients into the terminal ileum stimulates the secretion of many hormones that play an important role in obesity improvement 8 .
Single Anastomosis Duodeno-Ileal bypass with Sleeve gastrectomy‖ or SADI-S is a modification of DS operation at which only one anastomosis is performed. Decreasing the number of anastomoses decreases the incidence of postoperative anastomotic complications like leakage or strictures. Moreover, operative time is also decreased 9 .
Additionally, pyloric preservation decreases the incidence of dumping syndrome after duodenal diversion 10 .
The RYGB generally is one of the best-established procedures in bariatric surgery. Nevertheless, the failure rate with weight regain due to a dilatation of the gastric pouch, gastro-jejunostomy and proximal jejunum is up to 35%. Recently, bile reflux was identified as one important cause of postoperative pain. Again, a postpyloric reconstruction seems tempting for this procedure 11 .
Laparoscopic mini gastric bypass (MGB) (omega gastric bypass (OGB)) is newer bariatric procedures 12 . MGB has been reported to be a very safe, simple, and effective bariatric procedure. All the reports published to date have been very encouraging 13 Various studies of the MGB have reported excellent results with the additional benefits of being relatively simple to perform and associated with low complication rates 14 .

Patient preparation
All patients were subjected to complete medical history taking, thorough physical examination, and routine laboratory investigations. Serum cortisol and thyroid profile were also ordered to exclude hormonal disturbances that cause obesity. Additionally, echocardiography, ECG, as well as pulmonary function tests were also ordered. Upper GI endoscopy was performed for all patients to exclude the presence of hiatus hernia or significant reflux disease. Blood glucose level as well as HbA1c were also tested to assess the efficacy of diabetic control before operation.
Operative procedure Open loop duodenal switch procedure Under general anesthesia, all patients were explored via upper midline incision. After division of short gastric vessels, sleeve gastrectomy was performed by staples over 36-F bougie. Furthermore, the entire staple line was oversewn with continuous imbricating sutures. Duodenum was transected at the level of gastroduodenal artery and the distal stump was oversewn by absorbable sutures. After identification of ileocecal valve, an end to side hand sewn anastomosis was created between proximal duodenal stump and ileal loop 200-250 cm proximal to ileocecal valve. Methylene blue test was used to test for anastomotic and staple line leakage.
If the patient had gall stones, cholecystectomy was performed at the same session. Tube drain was inserted near to duodeno-jejunal anastomosis. Finally, abdominal wall was closed in layers.

Laparoscopic minigastric bypass
After abdominal insufflation and insertion of the four ports under visual guidance of the laparoscopy, the left liver lobe was retracted. Using harmonic scalpel or ligasure, a small window was created at the lesser omentum at the level of incisura adjacent to the lesser gastric curve. After creating a window to the lesser sac, an endostapler was used to create the horizontal border of the gastric pouch after bougie insertion. If there were any adhesions hindering the stapler way to the cardia, it was dissected before completion of the gastric pouch.
The vertical part of the gastric pouch was usually created by two or three cartridges. After that, the transverse mesocolon was retracted upwards to make good view of the DJ flexure. Gastrojejunostomy was created between the gastric pouch and the jejunum about 250 -300 cm away from DJ. The anastomosis was created by blue cartridge and the remaining defect was closed by Vicryl 3/ 0 sutures. A methylene blue test was performed after closure of the afferent and afferent bowel loops.

Follow up
All patients were followed three weeks, three months, six months, and one year postoperatively. Patients were assessed for complications, weight, BMI, and laboratory investigations including CBC, liver and renal function tests, lipid profile, blood glucose levels, calcium, and HbA1c.

Statistical analysis:-
The study was performed at 95% level of significance and power of 80%. The collected data were coded, processed and analysed using the SPSS (Statistical Package for Social Sciences) version 22 for Windows® (SPSS Inc, Chicago, IL, USA). Qualitative data was presented as number (frequency) and Percent. Normally distributed data was presented as mean ± SD and range (minmax). Paired t-test was used for comparison within groups. Student t-test was used to compare between two groups. P < 0.05 was considered to be statistically significant.

Demographic data
The mean age of the included patients was 34.76 and 36.0 years for DS and MGB groups respectively. In each group, 20 females (80%) as well as 5 males (20%) were included. The mean BMI of the included patients was 52.59 and 51.6 kg/m 2 for both groups respectively. When dividing each group according to BMI, each group included 15 patients (60%) with BMI between 50 -60 kg/m 2 , and the remaining 10 patients (40%) were having BMI of 40 -50 kg/m 2 . No significant difference was detected between the two study groups regarding demographics (p > 0.05). These data are illustrated at table (1).

Comorbidities
Regarding comorbidities, DS group included 15 patients with diabetes (60%) as well as 12 patients with hypertension (48%). On the other hand, MGB group included 10 diabetic patients (40%) in addition to 9 hypertensive patients (36%). The remaining comorbidities are shown in the following table. No significant difference was detected between the two groups regarding pre-existing comorbidities.
Furthermore, 4 patients presented with gall bladder stones 1 case in the SADI-S group and underwent cholecystectomy with the duodenal switch and 3 patients in the MGB group 2 of them underwent cholecystectomy with the operation. These data are illustrated at table (2).

Preoperative laboratory parameters
When it comes to the preoperative laboratory parameters, no significant difference was detected between the two groups regarding albumin, lipid profile, or HbA1c levels. These data are shown at table (3).

BMI and laboratory changes 3 months after operation
At 3-month follow up, BMI has decreased down to 48.45 and 49.35 kg/m 2 for both groups respectively. Both lipid profile and HbA1c showed improvement in both groups. Nevertheless, no significant difference was detected between the study groups regarding these parameters (p > 0.05). These data are shown at table (5).   Post-operative complications are illustrated in the following table. Post-operative leakage occurred in one patient in the MGB group. This patient presented one week after discharge with fever, tachycardia, and acute abdominal pain investigation was done and show leukocytosis and electrolyte imbalance. Besides, abdominal sonography showed free fluid in the abdomen. Open laparotomy was done revealing turbid fluid and pus in the peritoneal cavity for which aspiration was done, disruption of the gastro-jejunostomy was detected. The decision was to undo the operation. The jejunal loop was separated from the gastric pouch and repair was done to the anastomotic site. The lower part of the gastric pouch was resected and gastro-gastrotomy was done (minigastroplasty) with feeding jejunostomy. Then the patient was admitted to the intensive care unit and died.
In the MGB group 2 patients was admitted in the post-operative period. One case due to leak and the other patient was admitted 6 months after operation due to malnutrition in the form of hypoalbuminemea and the patient received treatment in the inpatient ward in the form of iv fluids, electrolyte, iv plasma and iv albumin and the patient was discharged 1 week later. These complications are shown at table (8).

Outcomes in OSA patients
All OSA experienced full improvement after surgery in both groups (p = 1). These data are illustrated in table (11). Discussion:-1. BPD/DS procedure was found to be superior to all other bariatric procedures as reported by Buchwald's landmark meta-analysis as it achieved 70.1 % excess weight loss, as compared to 61.2 % and 45% for gastric bypass and adjustable gastric banding respectively. Of note, this superiority is more noticed in superobese individuals [16][17][18] . 2. Since the first Mini-Gastric Bypass (MGB) was performed by Dr. Robert Rutledge in 1997, the MGB has had a long and circuitous route from conception to widespread adoption. Much of the 20-year gestation of the MGB was related to misunderstanding and confusion of some basics of general surgery, their application and the specific technique of the MGB. There is now recognition of the MGB as a good and maybe the best form of bariatric surgery 19 . 3. This study was conducted at Mansoura University Hospitals aiming to compare between the outcomes of loop duodenal switch and minigastric bypass in obese individuals. A total of 50 obese patients were included in the study and they were divided into two groups, each includes 25 patients. 4. In the current study, the mean age of the included patients was 34.76 and 36.0 years for DS and MGB groups respectively. No statistically significant difference was found between both groups (p = 0.622). 5. In another study that evaluated the role of loop DS in obese individuals, The mean age of the included patients was 50 years (range, 21 -71 years) 20 . In another study that compared the effects of gastric bypass to loop DS, the mean age of the included patients in DS group was 51.9 ± 13 years 21 .
6. Deitel and Kular conducted a consensus on minigastric bypass surgery in 2018. The mean age of the collected patients was 43.5 years 22 . 7. In the current study, the mean BMI of the included patients was 52.59 and 51.6 kg/m 2 for both groups respectively. When dividing each group according to BMI, each group included 15 patients (60%) with BMI between 50 -60 kg/m 2 , and the remaining 10 patients (40%) were having BMI of 40 -50 kg/m 2 . No significant statistical difference was detected between the two groups regarding BMI in our study. 8. In another study that evaluated the safety and efficacy of loop DS, the mean BMI of the included patients was 57.3 + 9.2 kg/m 2 23 . 9. Magouliotis and his associates compared the effects of minigastric bypass to Roux-en-Y procedure. The mean BMI of the included patients for MGB was 43.8 kg/m 2 24 . 10. In our study, in each group, 20 females (80%) as well as 5 males (20%) were included. Therefore, gender did not constitute a difference between the two study groups (p > 0.05). 11. In another study, MGB group included 60 males (66.7%) in addition to 30 females (33.3%) 25    in one study 27 . Conversely, the mean operative time for MGB was reported to be 55 minutes in another study 25 . 23. Regarding post-operative complications in our patients, DS group reported 2 patients of incisional hernia in the midline scar (8%) while leakage, readmission, mortality, and reoperation were not reported. When it comes to MGB patients, 2 patients (8%) were admitted in the post-operative period. One case due to leak and the other patient was admitted 6 months after operation due to malnutrition in the form of hypoalbuminemea and the patient received treatment in the inpatient ward in the form of iv fluids, electrolyte, iv plasma and iv albumin and the patient was discharged 1 week later. The only reported mortality case was reported in MGB group in the patient who had leakage and reoperation. 24. Dijkhorst and his associates reported that short-term complications occurred in 4 patients in loop DS group (6.1%). Three patients required admission, from whom, 1 case was explored revealing intraperitoneal abscess with no evidence of leakage. No incisional or port site hernias were reported on the long term follow up 27 25. In another study handling loop DS, there was one anastomotic leak, one patient was reoperated for hemoperitoneum and one patient was reoperated for an incarcerated umbilical hernia 20 .
26. Deitel and Kular reported that leakage was reported in 0.4% of the included patients of MGB procedures. Moreover, 30-day mortality was 0.03% in the same study 22 . Only Kular, with his analysis on 1054 patients who underwent MGB, found a lower rate for this complication (0.1%) 29  However, they demonstrated that MGB had a significantly better incretin effect than SG at longer follow-up. The improvement of the incretin effect is explained by the increase of GLP-1 serum levels 42 . 44. In our study, regarding hypertensive patients, no significant difference was detected between the two groups (p = 1). Four patients (33.33%) experienced relief of hypertension in DS group, compared to 3 patients (33.33%) in the other group. 45. Resolution of hypertension after MGB was reported to be ranging between 76.8 -80.6% after 1 year. Besides, this resolution rate declined 5 years after surgery (69 -78.6%) 22 . 46. In addition to added benefit of superior weight loss in patients undergoing DS, patients also enjoy higher frequency of improvement of resolution of comorbidities such as hypertension, and sleep apnea as reported in a previous report 43 . 47. All OSA patients (100%) experienced full improvement after surgery in our study in both groups (p = 1). 48. The reported resolution of OSA after MGB was reported to range between 87.0 -95.4% after 1 year. At 5-year follow up, OSA resolution has been reported to be 86.7 -93.2% 22 . 49. Buchwald and colleagues, in a meta-analysis of 32 studies with 4035 patients who underwent a biliopancreatic diversion or BPD-DS, reported that BPD-DS is the surgery offering the best long-term excess weight loss (EWL of 70%), improvement or remission of T2DM in 98%, resolution of hypertension in 81%, resolution of sleep apnea in 95%, and improvement of hyperlipidemia in 99% 16 . 50. The main drawback of this study is that included a small sample size (n = 25 patients). Furthermore, the follow up of the patients included short and medium term only. As a result, more studies including larger number of patients with longer follow up periods should be conducted in the future.

Conclusion:-
Based on the results of the current study, it was evident that both loop duodenal switch and minigastric bypass procedures are effective in the management of morbid obesity and its related comorbidities. However, loop DS operation is more effective in weight loss when compared to MGB.