Metabolic bariatric surgery is a relatively new surgical speciality becoming very popular during the beginning of the 21^st century due to worldwide epidemic of obesity, T2DM and cardiovascular disease

It is also a surgical field that continues to evolve rapidly due to the improvements in technology as well as better understanding of how the body’s physiology interacts with food and nutrition

It is important to appreciate the perfect metabolic bariatric surgery does not exist, each procedure has their unique advantages and disadvantages

• Currently certain procedures such as the sleeve gastrectomy, one anastomosis gastric bypass and Roux Y gastric bypass are the most commonly performed primary or revision/conversion metabolic bariatric surgery around the world because of its proven efficacy (mid to long term results) and safety
• Recently newer innovative procedures have been introduced into the mix, which include SADI-S, SASJ or SASI, however more studies are needed for the long term safety and complication rates
• Where as some other procedures have been abandoned or rarely performed nowadays, such as the jejunal ileal bypass, VBG, gastric band or the complicated BPD-DS

Currently in 2025-2026, the laparoscopic sleeve gastrectomy is still the most popular primary metabolic bariatric surgery in the world today

On the other hand, the sleeve bypass procedures are rarely performed in Australia or Western countries

• They are more acceptable to surgeons in Asia because of the higher rates of upper GI cancers and the need for gastroscopy surveillance of the distal stomach and proximal duodenum

This blog provides free general information for anyone who is seeking to understand more about the sleeve bypass procedure, not intended as a medical consult. Please seek proper medical advice for individual assessment and management.

The historical JIB is mentioned below first, which was the original concept using the intestinal bypass to create weight loss and metabolic hormonal changes. There is no gastric resection (sleeve gastrectomy) or creation of a proximal gastric pouch.

The sleeve bypass procedure is different because the sleeve gastrectomy is performed first followed by several different types of diversion or sleeve plus procedures, they include:

• Intact sleeve gastrectomy with small bowel anastomosis (SG-JI, SG-JB, SG-JJB, SADI-S)
• Intact sleeve gastrectomy with gastric anastomosis (SASJ, SASI)
• Divided sleeve gastrectomy or gastric pouch with gastric anastomosis (OAGB, RYGBP)

This blog also report on some available preliminary results comparing the sleeve bypass procedure versus the OAGB and SADI-S, below.

Please note these sleeve bypass procedures are mainly for weight loss and control of Type 2 diabetes mellitus. For severe reflux, the primary or conversion sleeve to Roux Y gastric bypass is still the preferred option.

Open jejunal ileal bypass (JIB)   The JIB was first introduced in the 1950s and abandoned in the 1980s due to the severe irreversible malabsorptive complications, including electrolyte imbalance, kidney stones, arthropathy, osteoporosis, liver failure and its associated high mortality rate   There is no sleeve gastrectomy performed. The procedure entails division of the small bowel 35cm distal to the ligament of Treitz and re-anastomosis it to the ileum, with 50cm of small bowel left for absorption of nutrients *This is a Roux Y reconstruction with a significant blind loop and a very short common channel resulting in significant malabsorption and malnutrition

Laparoscopic sleeve gastrectomy plus jejunal ileal bypass (SG-JIB or SG-JB)   This is different to the JIB in terms of the length of the common channel and amount of surface area left for small bowel absorption   The SG-JIB procedure entails performing a sleeve gastrectomy with a 48Fr bougie, the jejunum is transected 75cm distal to the ligament of Treitz and anastomosis created 75cm proximal to the ileo-caecal valve   The SG-JB procedure entails performing a sleeve gastrectomy with a 36Fr bougie, the jejunum is divided 30cm distal to the ligament of Treitz and anastomosis performed 250-300cm distal to the division site *This is a Roux Y reconstruction with a shorter blind loop and a longer common channel *This helps preserves most of the absorptive small bowel, lowers the probability of post op malnutrition and hepatic complications, aim to provide weight loss and metabolic benefits ***In theory there is also a blind loop with the potential for mucosal atrophy and bacterial overgrowth but this has not been proven so far

Laparoscopic sleeve gastrectomy plus jejuno-jejunal bypass (SG-JJB)   This was introduced in 2003 as a hybrid procedure to the RYGBP. *The sleeve was performed with a 36Fr bougie *The jejunum was divided 20cm distal to the ligament of Treitz and re-anastomosis 200cm distal to the transection point (please note this is very similar to SG-JB described above except the sleeve is created with the standard 36Fr bougie and anastomosis is to the more proximal part of the jejunum) *This is a Roux Y reconstruction with a shorter blind loop and an even longer common channel ***In theory there is also a blind loop with the potential for mucosal atrophy and bacterial overgrowth but this has not been proven so far *The pylorus and duodenum is similarly preserved, which allows future gastroscopy and ERCP   The SG-JJB is technically much more simpler than the RYGBP and SADI-S with less side effects/complications from the gastric bypass procedure *The SG-JJB offers similar results to the RYGBP in terms of weight loss and resolution of T2DM and at the same time may reduce the post op complications of the gastric bypass and its nutritional deficiencies ***However one study found that the RYGBP was found to be more effective in controlling hyperlipidaemia than the SG-JJB *With the SG-JJB, the incidence of dumping, anaemia, gallstones and GIT dysfunction is less after 5 years *SG-JJB avoids the potential for internal hernia at the Petersen’s space and without the gastric anastomosis, there risk of gastric (marginal) ulcers may be avoided as well     Like any sleeve procedure, there is a risk for reflux after the SG-JJB *One study reported 33.5% denovo reflux and majority of them are managed with medications *Conversion to RYGBP is relatively easy by anastomosing the gastric pouch to the bypassed jejunum

Single anastomosis laparoscopic sleeve gastrectomy plus jejunal or ileal anastomosis (SASJ, SASI)   The SASJ entails performing a sleeve gastrectomy with a gastro-enterostomy 150-200cm distal to the DJ flexure   Some versions of SASI entails performing a sleeve gastrectomy starting 6cm from the pylorus and a 3cm diameter gastro-enterostomy performed with loop of small bowel 250-300cm proximal to the ileo-caecal valve   This is different to the SG-JIB or SG-JB because it is a single (loop) anastomosis, there is no Roux Y reconstruction and no small intestine blind loop   Because of the sleeve to small bowel anastomosis, there may be a risk for marginal ulcers, bile reflux and food retention in the stomach or regurgitation

SASI   Background: *The sleeve gastrectomy remains as the most popular metabolic bariatric surgery worldwide *With time surgeons have designed additional or innovative alteration to the primary sleeve procedure, which included the ileal diversion (by Santoro) and then the single anastomosis sleeve ileal bypass (SASI by Mui and Mahdy)   The SASJ or SASI preserves all the benefits of the sleeve gastrectomy but also provides an additional benefit of the proximal small bowel bypass effect plus preserving the continuity to the duodenum to allow for future gastroscopy and ERCP   The techniques essentially entails: *Gastric restriction with a bougie size varies between 32 to 40Fr *The hiatus hernia should be repaired at the same time *According to some surgeons, the sleeve + fundoplication may be performed at the same time if necessary in some cases     SASI entails having a larger gastric pouch (3cm wide with a 150-200mls volume), connecting the antrum (2-6cm proximal to the pylorus) to the ileum (with anastomotic length <3cm and a common channel of 300cm) *The slightly larger gastric pouch (compared to the sleeve) may help with better food tolerance, better nutrition and preserved gastric acid secretion *The longer bypassed segment leads to greater weight, greater partial bile resorption and less bile reflux into the stomach and potentially greater malnutrition risk

SASI vs OAGB results The one anastomosis mini gastric bypass (OAGB) was described in 2002 and modified by the surgeons in Spain (Carbajo), is the creation of a longer gastric pouch (>20cm), afferent loop fixation, with a 2.5cm gastro-enterostomy *Some surgeons may tailor the bilio-pancreatic limb according to the total bowel length, however more nutritional deficiencies has been reported when the BP limb is over 200cm *The hiatus hernia should be repaired at the time of the OAGB to reduce the risk of acid/bile reflux Data so far reported 12 cases of gastric adenocarcinoma possibly due to bile reflux, at the GJ anastomosis, GOJ or the proximal gastric pouch       Meta analysis and systematic review reported that both SASI and OAGB *have greater weight loss compare the primary sleeve and Roux Y gastric bypass *achieved comparable sustained weight loss outcome, with a slightly better %TBWL favouring the SASI group   There was no significant difference in outcomes in albumin, vitamin B12 and D levels with SASI shower better nutritional outcome   But in the longer term SASI may have higher rates of malnutrition likely due to the longer segments of bypassed small bowel   One case of gastric neoplasia has been reported after the SASI

SADI-S   Single anastomosis duodeno-ileal bypass was described in 2007 to simplify the original BPD-DS operation   SADI-S was eventually approved by ASMBS in 2020 and has been performed as a primary or revision/conversion procedure   Recent study on the conversion to SADI-S versus RYGBP reported that rSADI-S has less operative time, similar post operative complication, less small bowel obstruction with similar hospital re-admission rates and mortality rates between the two   However RYGBP remains the most common revision/conversion procedure after sleeve gastrectomy, gastric band and duodenal switch