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

Please also read the section below on sleeve plus diversion or SASI

One anastomosis transit bipartition (OATB)

Single anastomosis sleeve ileal bypass (SASI)

Single anastomosis sleeve jejunal bypass (SASJ)

Please note:

The above is not the same as the single anastomosis gastro-ileal bypass (SAGI) which does not include a sleeve gastrectomy resection

Introduction:

A new emerging surgical technique for metabolic syndrome (esp. T2DM)

• The advantage is the potential for a lower rate of nutritional complication
• Maintaining access for gastroscopy and ERCP to the duodenal area

The context is that our modern Western diet nowadays is very rich in refined/processed hypercaloric food types, which causes an imbalance between proximal and distal gut function

• In the jejunum there is an exaggerated hyper absorption of carbohydrates
• In the ileum there is a shortage of fiber and instead the more complex nutrients are delivered, with reduced production of GLP-1 and FGF-19, leading to imbalance and dysfunction of the multiple microbiological mechanism

The sleeve gastrectomy is very effective for volume eaters and binge eaters but far less effective for patients who snacks or consume high calorie liquids

With modern eating habits and the specific diet types described above it is perceivable that the sleeve gastrectomy will fairy a significant proportion of the patient with time

• The long term issues after a sleeve gastrectomy include inadequate weight loss, weight regain, recurrence of T2DM and gastro-oesophageal reflux

The Roux Y gastric bypass on the other hand is a much more technically challenging procedure with potential anatomical and physiological side effects and complications

The transit partition is developed as an in between operation between the sleeve and RYGBP

History:

The concept of sleeve gastrectomy plus transit bipartition (LSG-TB) was developed by Santoro in 2003 and the procedure was offered in 2006

The OATB was first proposed in 2014 (by Mui) and 2016 (by Mahdy)

The LSG-TB surgical technique is:

• Sleeve gastrectomy with gastro-ileal (260cm from ileo-caecal junction) and ileal-ileal anastomosis (80cm from ileal-caecal junction)

The OATB surgical technique is more simpler, a single anastomosis (SASI):

• To create a sleeve gastrectomy 7-8cm above the pylorus to allow a 3-4cm gastro-ileal anastomosis and leave 4cm between the distal anastomosis and the pylorus
• For the SASI measure 250-300cm proximal to the ileo-caecal valve for the anastomosis
• For the SASJ measure 150cm distal to the DJ flexure
• Anti-reflux stitch (by Carbajo 2005) with 8cm of afferent loop to the sleeve staple line

The surgery offers 4 effects on the GIT:

• Restriction
• Satiety (hypothalamic centre, reduced gastric emptying)
• Jejunal hypoactivity (reduce GIP, reduce glucagon) (foregut theory described by Rubino, rise in entero-insulin levels and fall in anti-entero-insulin levels)
• Ileal hyperactivity (increase GLP, PYY, oxyntomodulin by the L cells and FGF-19 by the enterocytes) (hindgut theory with rise in entero-insulin levels)

Anatomical advantage:

The gastro-ileostomy may also be an escape valve, increases the oesophago-gastric pressure gradient and reduces the reflux

• One multi centric study in 2020 reported that the OATB has less reflux compare to the one anastomosis gastric bypass (OAGB)
• Another study reported the OATB has better diabetic control, less reflux and less hypoalbuminaemia

The gastric antrum and duodenum is still in continuity, which allows duodenoscopy and ERCP to diagnose and treat biliary and pancreatic disease

Physiological advantage:

• The incretin GLP-1 is for reduced gastric emptying, satiety and appetite suppression, to control weight and metabolism
• FGF-19 increase fatty acid oxidation and there is a clinically inverse association between FGF-19 and the severity of coronary artery disease
• More bile acid reaching the ileum faster and absorbed, upregulation of the farsenoid X receptor and G protein coupled membrane receptor 5 which improves the regulation for normal metabolic pathways
• The bile salts may the favourable gut bacteria and modulate the microbiota

Adverse effects:

Nutritional consequences

• Diarrhoea
• Folate and vitamin D deficiencies as well as elevated levels of PTH were observed
• Very small number of patients reported to have hypoproteinaemia and anaemia

Similar to the OAGB (which has been performed since 1997) there are concerns about bile reflux and gastric cancer

• However most of the patients have diluted bilio-enteric fluid reaching the gastric pouch without any clinical relevant symptoms of alkaline/bile gastritis
• There may be a risk for late marginal ulcer development
• There may be a risk for gastroparesis or delayed gastric emptying, food residue in the stomach and regurgitation/vomiting who may eventually need a conversion to Roux Y gastric bypass

Results:

The LSG-TB reported 87.7% EBMIL and 20% TWL at 2 years

Santoro (in 2012) reported that the LSG-TB was 74% effective for weight loss

Several authors reported 80-86% remission for T2DM, 72-77% resolution for HPT, 70% improvements in hypercholesterolaemia and hypertriglyceridaemia, 88% remission for OSA

The weight loss result of the LSG-TB has been reported to be better than the standard RYGBP (% EBMIL 85.3 vs 73.9%, %TWL 44.8 vs 38.4%)

• Similarly it has been reported that OAGB has better weight loss results than RYGBP
• But less than the BPD-DS as expected (% EBMIL 78.6 vs 83.7%, %TWL 41.3 vs 54.7%) (but the BPD-DS has more complications and potentially significant long term adverse nutritional consequences)

Mahdi (in 2016) reported SASI had 90% EWL in 1 year and also greater %TWL and %EWL than the OAGB

• They reported that the SASI has 83.9% complete remission of T2DM, improvement in hyperlipidaemia in 65%, in HPT 36%, in GOR in 92.1% and in OSA in 57.8% of the patients

When the SASI or OATB was compared to the long limb RYGBP, there was no significant differences in weight loss or reduction of co-morbidities in the short term

Apart from weight loss, SASI outperform the LSG and OAGB in terms of improving T2DM (97.7% vs 71.4% vs 86.7%)