Planning before gastric bypass surgery   Patients who smoke cigarettes, vape or consume large volume of alcohol will not be considered for gastric bypass surgery   Patients are advised against taking non steroidal anti-inflammatory (NSAIDs) tablets   Younger female patients (in the reproductive age group) need to make sure they are not pregnant before surgery and for about 12-18 months after surgery *Please talk to your GP about contraception for the 12 months after surgery (oral contraceptive pill, implants or Mirena IUD).   Also please read the Delphi 2024 consensus recommendations post OAGB (below)

Background for gastric bypass (OAGB and RYGBP)

The RYGBP   Has been described as the gold standard for weight loss for half a century with consistent reports of 30% TBW in the first 12 months   Despite that weight regain still occurs in 37% of patients after 1 year It is estimated that 12% of patients have revision surgery for complications or inadequate weight loss *Since assess to bariatric surgery has increased so much in the last decade and the number of patients presenting for revision surgery and its complexity also has also increased   It is very difficult to revise a RYGBP procedure (eg distalization of the gastric bypass) Revision surgery also have significant risk and complications   The endoscopic gastric pouch plication is an option for candidates with weight recurrence/regain, who are not suitable for revision surgery & who does not have GOR *The complication rate is low however the results are unpredictable The main reason for re-operation after RYGBP is for internal hernia and small bowel obstruction The incidence of internal hernia is reported to be 8-15% *Despite evidence suggesting the efficacy of closing the mesenteric defect, the incidence of internal hernia requiring re-operation has been reported to be up to 8% In the long term there is a greater risk for re-admission to hospital and a higher mortality rate after the RYGBP due to trauma, hypoglycaemia, dumping, mental health disorder, suicide and alcohol abuse   The gut related complications (marginal ulcer, internal hernia, reduced absorption of nutrients) after RYGBP is much higher compared to the sleeve   The overall revision surgery rates after the RYGBP has been reported up to 20%

The OAGB Around the world the one anastomosis gastric bypass (OAGB) has been reported to be the 3rd most common bariatric procedure. More recently in parts of Europe and Asia the OAGB has become the second most common bariatric operation after the sleeve gastrectomy. Data from the Bariatric Surgery Registry (BSR) reported that the OAGB has overtaken the Roux Y gastric bypass (RYGBP) as the second most common bariatric procedure in a few centres around Australia OAGB has good weight loss result and resolution rate for T2DM, comparable to the RYGBP The OAGB complication risk may be less than the RYGBP in terms of internal hernia/small bowl obstruction and dumping Bile reflux may occur after OAGB but this may not be as common or as clinically significant as we first believe *The conversion rate to RYGBP is small maybe around 1% *The risk of metaplasia or cancer in the gastric pouch and oesophagus have not been published after 2 decades of the OAGB being performed

The sleeve gastrectomy The sleeve gastrectomy is recommended for the majority of patients because it has less risk and complications *The reflux and weight regain are the most common concerns after a sleeve but still safer than the gastric bypass   The most common reason for revision after a sleeve gastrectomy is for severe acid reflux, the revision rates has been reported between 2 to 6%   Interestingly please note that the sleeve vs gastric bypass SLEEVEPASS trial with detail gastroscopy check and up to 10 years of follow up, demonstrated similar cumulative incidence of de novo Barrett’s oesophagus between sleeve and RYGBP *This has been reported in some other larger retrospective studies as well *The association between sleeve gastrectomy, reflux and oesophageal adenocarcinoma is yet to be proven   The gastric bypass has a lot more follow up issues, side effects, risk and complications both in the short and long term *There common issues are listed below and there may be a lot more not mentioned in this section *Some of these complications are extremely serious with a higher risk for hospital re-admission and small risk of mortality *Some patients may need the gastric bypass reversed Please do your research carefully before contemplating metabolic and bariatric surgery Some patients regret choosing the gastric bypass instead of a sleeve gastrectomy because of the long term issues, complications and weight regain (even with the bypass)

Disadvantages of a gastric bypass

Marginal ulcers at the gastro-jejunostomy site affect 0.6 to 16% of the patients and up to 30% of patients may be asymptomatic

• Symptoms include epigastric pain, vomiting and perforation

Internal hernia may occur up to 10% after RYGBP

• The risk is increased without closure of the Petersen’s defect
• The risk is increased with smoking, weight regain and pregnancy (especially during the 3^rd trimester)
• The rate of internal hernia may be less with the OAGB group

Chronic abdominal pain may occur in 15-30% (range 7 to 54%) of patients after the RYGBP

• Chronic abdominal pain can occur after the OAGB as well

Chronic abdominal pain after gastric bypass The patient risk factor for developing chronic pain include: *Younger age *Smoking *T2DM *Depression *Post op complications Some studies have reported that 34-54% of patients report abdominal pain after bariatric surgery *4-29% of patients are re-admitted back to hospital with abdominal pain at least once after surgery   The common causes include gallstones, internal hernia, small bowel obstruction, gastric ulcer related complications, abdominal wall hernia   *One Dutch study reported persistent abdominal pain even after cholecystectomy in 10-41% of patients *Another study reported persistent pain in 51% of patients 6 month after cholecystectomy   Sometimes the cause of abdominal pain can’t be found even after a diagnostic laparoscopy *One study found that half of patients continue to experienced abdominal pain 3-6 months after re-operation *One study did report improvement in pain after 6 months in 17.6% of the patients even when no diagnosis was found   In general or in summary: *Chronic pain adversely impacts the overall quality of life and psychological distress for the patients *Re-operation for chronic abdominal pain is common after bariatric surgery but unfortunately still almost half the patients continue to experience pain after re-operations with no discernible cause found

Marginal ulcers Marginal ulcers at the gastro-jejunostomy (GJ) site affect 0.6 to 16% of the patients and up to 30% of patients may be asymptomatic Symptoms include epigastric pain, vomiting and perforation *Stomal ulcer does occur in about 1% or maybe up to 3-5% after OAGB and RYGBP 25% of ulcers are seen within 12 months after RYGBP *Risk factors may include longer gastric pouch (>5cm), large pouch volume (>50cm3), anastomotic ischemia, staples/sutures, patient’s co-morbidities (HPT, T2DM) as well as other factors such as smoking/vaping (2 fold increase), alcohol, NSADIS, steroids, immunosuppressant medications, past history of pepetic ulcer disease or Helicobacter pylori infection     The pathogenesis is unclear and may be related to increase gastric acid production, impaired microcirculation of the gastric pouch and or the Roux limb   There may be a lower risk of gastric ulcers in OAGB group compare to RYGBP because of the alkaline bile content or perhaps the lower blood supply in the Roux limb   The average time for ulcer formation may be 14 months (+/- 10 months) Most gastric ulcers present within 2 years   Most patients only take prophylactic PPI medications for 3 months, rarely after 6 months     Recalcitrant gastric ulcers prevalence may be 13% and gastro-gastric fistula require further surgery Resection and creation of a new GJ anastomosis is required     Management: Prophylactic PPI medication on a longer post op period is recommended to at risk patents Re-operation rates for marginal ulcer may be up to 9%

Internal hernia   Eindhoven 2020 (EVH 20) scoring system on CT scan *Swirl sign, mushroom sign, hurricane eye sign, clustered loops, right sided anastomosis *Small bowel behind SMA, small bowel obstruction, enlarged lymph nodes, venous congestion, mesenteric oedema, free fluid *Dilated alimentary or biliary limb, backward oral contrast flow to biliary loop or into the residual stomach   CT scan is not an accurate diagnosis for internal hernia The gold standard is a diagnostic laparoscopy

Small bowel obstruction (SBO) after gastric bypass   The incidence of SBO has been reported to be 1-6% after bariatric surgery especially RYGBP *Internal hernia account for 53% of SBO after elective bariatric surgery Common causes include adhesions, internal hernia, stenosis/obstruction at the jejeno-jejunostomy site, intussusception, port site and ventral hernia   6 months following gastric bypass is the risk timeframe for development of significant SBO   Operative intervention is often required for SBO after bariatric surgery and mortality rate has been reported to be 1.3%

Some recent Modified Delphi consensus regarding OAGB   Expert opinion stating that: Recurrent weight gain is more than 30% of initial surgical weight loss Suboptimal weight loss is <20% of total body weight loss within 2 years of surgery   Persistent bile reflux is the detection of bile in oesophagus during gastroscopy or bile scintigraphy at least 6 months after OAGB without good response to lifestyle modification, nutrition and medications   Resistant marginal ulcer is a persistent endoscopy proven marginal ulcer despite 6 months medical therapy including eradication of H pylori with the optimal dose together with suspension/withdrawal of aspirin, NSAIDs and smoking   Micro and macronutrient deficiencies without good response to nutritional support and medical treatment is defined as nutritional complications   Most experts recommend a trial of modern obesity management medication (such as GLP-1 analog) as an option before revisional/conversional surgery   If the level of C peptide is above 1ng/ml there is a good probability of diabetes remission.   For weight regain or worsening of obesity complication after OAGB, elongation of the BP limb is an option and measurement to ensure the common channel is at least 3-4m is necessary to avoid nutritional complication or pouch re-sizing in the case of an enlarged pouch is acceptable   For bile reflux after OAGB, repair of hiatus hernia and conversion to RYGBP with or without pouch re-sizing is acceptable   For nutritional complications resistant to nutritional support, increasing the common channel (shortening the BP limb), conversion to RYGBP or reversal of the OAGB is acceptable   With persistent marginal ulcer, resection of the gastro-jejunostomy including the distal pouch and conversion to RYGBP is acceptable or complete reversal of the OAGB

The more recent Deplhi 2024 consensus also recommended   Prophylactic medications such as PPI and urso-doexycholic acid be prescribed for at least 6 months to prevent acid reflux, gastric ulcer and gallstones/gall bladder issues.   A gastroscopy check after surgery but the timing and interval or frequency is yet to be determined