Roux Y gastric bypass

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

Please read the section on sleeve or gastric bypass as well for more information.



Laparoscopic Roux Y gastric bypass





The laparoscopic sleeve gastrectomy and Roux Y gastric bypass are the amongst the most commonly performed bariatric surgical procedures nowadays. Both have significant effect on long term weight loss (>50% excess weight loss after 5 years), reduction of cardio-vascular risk factors and reduction of premature mortality.


The challenge to surgeons is to optimize their surgical techniques for both these procedures, to maximize the weight loss results, maximize the beneficial health effects and minimize post op complications.



History of gastric bypass


The open gastric bypass was first introduced in 1966 by American surgeon Mason and Ito. The Roux Y reconstruction was added to the gastric bypass in 1977.

The laparoscopic RYGBP was first described by another American surgeon, Wittgrove in 1994.

More recently (in 1997) the laparoscopic one anastomosis mini gastric bypass has also been introduced.


Traditionally the RYGBP has been regarded as the gold standard to which other bariatric procedures are compared to. However this procedure are not that popular in Asia (especially Japan) because of the concerns about the potential risk for remnant gastric cancers.


As a side note, obviously after a standard RYGBP, there are very limited ability for endoscopist to perform a gastroscopy check to the remnant stomach or perform an ERCP for the treatment of common bile duct stones.


Note the estimated risk of gallstones and common bile duct stones after weight loss are about 10% and 1% respectively.

  • Specialised equipments such as single or double balloon enteroscopy or laparoscopic-endoscopic transgastric approaches are necessary if ERCP needs to be performed.


However because the risk of remnant gastric ulcers or cancers are rare in Western countries, this may not be an important or major deciding factor in choosing the RYGBP as a primary weight loss procedure for most patients in Australia.



Technical issues with RYGBP


The mechanism of the Roux Y gastric bypass are not completely understood. Previously it is thought that the proximal gastric pouch and stomal size is important for restriction and weight loss. Nowadays many surgeons believe that the bilio-pancreatic limb and total gut length are more important, not for restriction but for the hormonal or metabolic effects. Nevertheless some consistencies in the surgical techniques should be observed.


The gastric pouch is usually created around the crow’s feet and is about 50 to 100 mls in volume.

  • Some surgeons now believed that the proximal gastric pouch size/length or stoma size does not have good correlation with long term maintenance of weight loss.


The alimentary limb (AL) is usually about 100 to 150cm.

  • Short AL is usually between 40 to 100cm, standard AL is between 100 to 150cm and long AL is 175 to 250cm. Some surgeons recommend a longer alimentary limb for the super obese, BMI > 50.
    • It is generally accepted in the surgical community that the short AL have inferior weight loss result (especially for the super obese, BMI>50). But there may not be a statistical significant difference between the standard and long AL
  • The common channel is usually more than 300cm.

However the longer the exclusion of small intestine (longer AL with a shorter common channel), the higher the risk is for malabsorption.

  • At the present time there are no consistent length for the AL limb creation and how much it contributes to the long term effectiveness of RYGB, we are not sure.



The bilio-pancreatic (BP) limb is usually not measured and surgeons don’t have a standard guideline to follow as to how long the BP limb should be.

  • Nowadays some surgeons believe that the BP limb length may be the key to successful long term weight loss.

The BP limb could be maybe less than 25cm or more than 50 to 75 or 100cm from the ligament of Treitz.

  • The long BP limb (maybe around 150cm) could also be created with a shorter alimentary limb to reduce the total length of excluded small bowel (avoid making the common channel too short), to prevent the risk of serious malabsorption.


Some studies have shown that:

  • Longer BP length may have higher weight loss result initially but in the long term (beyond 4 years), the results may have no statistical difference to the shorter BP limb RYGBP.
  • The resolution of HPT and T2DM (secondary end points) may or may not be significantly different between these 2 groups after 2 years.
  • However the improvements in dyslipidaemia in the long term (beyond 2 years) may be better with the longer BP limb RYGBP.


Note, the longer limb BP is used in the one anastomosis gastric bypass (OAGB), which is usually about 150 to 200 cm from the ligament of Treitz.

  • Obviously there is no second anastomosis to further shorten the common channel and already some OAGB studies have shown a higher risk for malabsorption side effects compare to the standard proximal RYGBP.



The distal RYGBP is when there is a short common channel (CC), which is measured as 150cm proximal to the ileo-caecal junction.

  • The AL length varies depending the entire length of the small bowel but the BP and CC are consistent.
  • There may be no significant differences between standard and distal RYGBP in terms of weight loss and improvements in medical co-morbidities.


Obviously all the above may be confusing, will not tell us as to which one is the best technique and there will be ongoing debate amongst RYGBP surgeons.


Personally I agree with the majority of surgeons, who currently  recommend:

  • A long slender proximal gastric pouch creation (Poiseuilles’ Law states that flow rate or gastric emptying with a narrow diameter tube)
  • A proximal gastric bypass of 150cm is adequate, using a 50cm BP limb and 100cm AL.
  • The malabsorption risk is very low with the standard proximal RYGBP
  • A distal gastric bypass (longer AL) may not have superior weight loss outcome.
  • A longer BP limb (>50 to 120cm) may result in more weight loss or resolution of medical co-morbidities but may also increase the risk for macronutrient (protein) or micronutrient deficiencies.




The mechanism of RYGBP


There is a restriction component from the smaller proximal gastric pouch and a narrow anastomosis (gastro-jejunostomy) and a hormonal component, resulting in beneficial metabolic effect from alterations to the small bowel anatomy.

  • The extended (long slender) proximal gastric pouch may help with delay gastric emptying, a slow sustained delivery of nutrients into the hindgut, producing sustained changes in post prandial gut hormones.
  • The one anastomosis or Roux Y gastric bypass may have a hind gut effect, with more rapid delivery of nutrients to the distal small bowels, resulting in the release of GLP-1 hormone, a satiety hormone (ileal brake) and incretin hormone (this is believed to result in improvements as T2DM).
  • Gastric bypass also results in a higher level of serum insulin, GLP-1 and peptide YY.
  • Other effects may be mediated through alterations in vagus nerve signalling, changes in gut microbiota and changes to the bile acid metabolism.


Bile acids contribute to the to the improvements of T2DM through changes in the molecular pathways that impacts glucose metabolism, resulting in increased hepatic glycogenesis and increase energy expenditure (adaptive thermogenesis).

  • The bile acids metabolism changes with the different intestinal microbiome.
  • The bile acids binds to the farnesoid X receptor (FXR) which then induces the secretion of fibroblast growth factor 19 from enterocytes.
  • Some researchers believe that there is an increase in FGF19 levels after sleeve gastrectomy and gastric bypass, which may be important in the treatment of T2DM. This area needs to be researched further.


The longer BP limb (similar to the BDP-DS) may result in higher bile acids level and lower levels of total cholesterol, LDL cholesterol and triglycerides.




The outcomes of RYGBP


Studies have reported on the great success of RYGBP.

  • The long term excess weight loss is about 58%, resolution rate for T2DM is about 80% and resolution rate for dyslipidaemia ranges from 33 to 77%.


However weight regain occurs after all types of bariatric surgical procedures.

  • Up to 85 or 87% of patients regain weight after RYGBP.
  • The causes are often multi-factorial, perhaps less to do with the technical aspects of the surgery and more to do with patient physiology and other factors.


Obviously more excess weight loss is desirable with a more aggressive procedure but when it introduces nutritional side effects and other complications, the quality of life and the patient satisfaction rate will drop.

  • The most common micronutrient deficiencies are iron, vitamin B12 and folic acid deficiencies.
  • Deficiencies in Zinc and vitamin D need to be corrected as well.
  • In summary, if there are no statistical difference in weight loss or resolution of medical co-morbidities (such as HPT and T2DM) and if the risk of micronutrient deficiencies are problematic, surgeons may choose a less aggressive procedure (avoiding long AL or BP length, avoiding a short CC) to achieve acceptable long term weight loss result and still maintain a good health related quality of life.



The long term side effects and follow up by their general practitioners are important, especially with our current patient demographics.

  • Patients nowadays move around a lot (for work or other reasons), the long term follow up with their original GP or surgeon may not be possible.
  • Hence a younger patient in the remote areas may wish to avoid the RYGBP, where medical facilities may be limited or if there is a lack of doctors/specialists to address the anatomical complications of a RYGBP (such as stomal ulcers, strictures, gastro-gastric fistula, internal hernia, small bowel obstructions) or to address the functional issues (severe iron, zinc and vitamin deficiencies).




RYGBP is only one option for treating reflux or Barrett’s oesophagus after a sleeve gastrectomy


Please read the section on sleeve or gastric bypass regarding issues with reflux after a sleeve gastrectomy.


RYGBP is very effective in controlling heartburn symptoms in a majority of patients. However it is emphasized that the reflux symptoms may persist (partial resolution) or recur many years later.

  • Medications such as antacids (Gaviscon, Mylanta, etc) and proton pump inhibitors (PPI) medications may need to be continued in the long term.



RYGBP is an effective surgical treatment for sleeved patients with severe heartburn symptoms or those who had developed complications, such as erosive oesophagitis or Barrett’s oesophagus.

  • Improvement/resolution of over 40% of patients with long segment Barretts’s oesophagus and over 75-80% for short segment Barrett’s and erosive oesophagitis have been reported.
  • Barrett’s remission rates of 50 to 80% has been reported.
  • Some patients has been reported to be free of dysplasia after RYGBP.


In other words RYGBP does not always achieve complete resolution of the reflux symptoms or guarantee resolution of Barrett’s oesophagus.



RYGBP as a revision bariatric procedure


The RYGBP is a good revision surgery option after a failed gastric band or sleeve gastrectomy (for reflux and weight regain).

  • Some reports indicate that over 50-60% of patients after failed a gastric band and over 5% of patients after a sleeve gastrectomy may require revision surgery. The rate for revision surgery after a sleeve gastrectomy may be higher with longer follow up period. We will need to wait for long term data.
  • Revisional RYGBP offers more than just purely restriction, it also have beneficial physiological and metabolic effects from changes in the gastro-intestinal hormones.
  • Revision RYGBP is less drastic than the duodenal switch or SADI-S procedure and may have less nutritional/metabolic side effects or long term complications.
  • However patient selection is critical, noting that revisional surgery is technically more difficult to perform, the risk and potential complications (especially for leaks, bleeding) are higher and understand that weight loss outcome is inferior for revisional procedures.


Also please note that sometimes it is not possible to perform a primary RYGBP for super obesity (BMI > 60) or central android obesity.

  • In this case, a sleeve gastrectomy is preferred and the RYGBP may be a planned second stage procedure.
  • Obviously after the first procedure, the second procedure will not result in as much weight loss from the initial total body weight.







Micronutrient deficiencies after gastric bypass


The most common is iron deficiency anaemia, vitamin B12 and D deficiencies.

  • However it is also noted that a significant proportion of patients who present for bariatric surgery may already have iron and vitamin deficiencies.
  • This is carried over after the weight loss operation.


Iron deficiencies are attributed to reduced oral/dietary iron intake and absorption as a results of:

  • Reduced consumption of red meats
  • Decreased hydrochloric acid production (or PPI medications use), which is normally needed to reduce the ferric (3+) state to the absorbable ferrous (2+) iron state
  • Bypassing the duodenum and proximal jejunum (which are the primary sites for iron absorption)
  • Iron deficiencies are more likely to occur 2 to 3 years after the initial bypass operation.

Blood tests to measure ferritin and total transferrin saturation is needed



Vitamin B12 may occur due to:

  • Reduce consumption of animal protein
  • Reduced gastric acid production, which impair vitamin B12 metabolism and release from R-binding protein
  • Reduced production of intrinsic factor

Similarly vitamin B12 deficiencies are more noticeable 2 to 3 years after the initial bypass operation.


Vitamin B12 is needed for DNA synthesis and neurological function (to prevent demyelination and axonal degeneration)

Deficiency leads to:

  • Macrocytic anaemia, fatigue and glossitis
  • Neurological symptoms such as numbness/parasthesia (in hands, legs), ataxia, slow reflexes, vertigo, tinnitus, peripheral neuropathy and altered mental state



Folic acid is often associated with vitamin B12 deficiency

  • Folic acid is mainly absorbed in the jejunum, which will be bypassed
  • Deficiency may lead to high homocysteine levels and risk of atherosclerosis



Zinc is an essential trace metal for DNA synthesis, wound healing and protein synthesis. Zinc absorption occurs in the duodenum and proximal jejunum (in competition with copper).

  • Zinc deficiency occurs as a result of the bypassed proximal small bowel and is more noticeable 2 to 3 years after surgery.




Vitamin D deficiencies are the most common, which may occur in up to 90% of patients.

It is also estimated that 50-80% of patients may be vitamin D deficient before bariatric surgery.

This may be due to:

  • Inadequate sunlight exposure, patients participating in sedentary indoors activities
  • Reduced liver hydroxylation
  • Dietary deficiencies or poor absorption (due to loss of absorption of fat soluble vitamins from the intestine



Low calcium may be a result of:

  • Reduced dietary intake
  • Reduced gastric acid production
  • Reduced absorption from the bypassed duodenum and proximal duodenum
  • Reduced calcium absorption due to vitamin D deficiency and secondary hyperparathyroidism


Other mineral deficiencies include magnesium, folate, vitamin A, B1 and B6.



Vitamin B1 (thiamine deficiencies)

  • Absorption is from the jejunum
  • After bypass surgery and poor nutrition (eg. alcohol abuse and persistent vomiting), thiamine deficiencies is common

Symptoms may include:

  • Neuro-muscular disorders, learning difficulties, impaired short term memory, coma
  • Serious cases of Beri-Beri can affect the heart, peripheral and central nervous system



Vitamin B6 (pyridoxine)

On the  contrary excessive replacement of vitamin B6 should be avoided to prevent neurological symptoms





The organic source of selenium is mainly from cereals, eggs, fish, meat and Brazil nuts

Selenium is absorbed in the duodenum and proximal jejunum by chelating/binding to organic and amino acids

The inorganic selenium (selenate, selenite) in supplements and food fortifiers are less readily absorbed

  • Deficiency may lead to cardiomyopathy (Keshan disease), osteo-athropathy, thyroid gland dysfunction, cretinism, immune suppression, male infertility and hypercholesterolaemia

On the contrary high levels of selenium may lead to gastro-intestinal upsets, hair loss, fatigue, irritable and nerve dysfunction





Changes in bone metabolism after gastric bypass


After a gastric bypass, there is a significant increase in osteoclast activity after 1 year. There is a significant bone resorption in the year after the gastric bypass. Post-menopausal women are more likely to have an increase in slerostin activity compared to the pre-menopausal group after the gastric bypass surgery, with an increased rate of bone loss.


Definitely compare to the sleeve gastrectomy, the gastric bypass:

  • Is more likely to result in lower serum calcium and 25-hydroxy vitamin D, a higher level of phosphorus and parathyroid hormone (PTH).
  • Bone strength/density is more likely to be reduced and secondary hyperparathyroidism is more common after a gastric bypass.


This may lead to:

  • Accelerated bone remodelling, increased bone turnover, decrease bone mineral density, osteomalacia, osteoporosis and pathological fracture.
  • Hence sometimes it is advisable for post menopausal women who is at risk for osteopenia or osteoporosis to avoid the gastric bypass procedure.



PTH stimulate kidney synthesis of vitamin D, which then becomes part of the negative feedback loop.

PTH increases serum calcium and suppress phosphate metabolism.

Vitamin D increase calcium and phosphate metabolism, to provide minerals for bone formation.


After a gastric bypass, some endocrinologist and dietician recommend lifelong calcium and vitamin D supplements.

1000 IU vitamin D per day (maybe even larger doses for at risk patients)

1200 – 2000mg calcium per day





Post op supplements


The American guidelines suggest that the RYGBP patients should receive at least 3 000 Units of Vitamin D and 2.4g calcium citrate, as well as the usual iron and multivitamin supplements.


With the OAGB patients, possibly more iron and calcium supplements are needed because of the exclusion of the proximal small bowel.

  • Copper and zinc levels should be checked as well.


Patients with a longer bilio-pancreatic limb (>250cm) are more at risk for iron, vitamin B12 and vitamin D3 deficiency.

  • Hypoalbuminaemia may result in the development of non alcoholic steatohepatitis (NASH).
  • Acute liver failure with severe protein deficiency may lead to increased mortality.


Obese patients, especially sedentary (lack of mechanical loading to the joints) patients with lack of sunlight exposure are already at risk for low vitamin D levels and elevated parathyroid hormone levels.

  • Secondary hyperparathyroidism may be exacerbated by the malabsorptive state.
  • Vitamin D supplements may help to reduce bone loss, reduce secondary hyperparathyroidism and the risk of fractures.






Weight regain after weight loss surgery


Weight regain will occur after any bariatric surgery with time.

Weight regain may be associated with the return of medical co-morbidities (hypertension, T2DM) and reduced health related quality of life


It is estimated that patient will regain 5-10% of their total weight loss (TWL) within the first decade after bariatric surgery


The percentage of patients who develop weight regain after a sleeve gastrectomy and RYGBP may occur up to 76-87% or more.


Specifically with regards to the RYGBP

  • The Swedish Obese Subject Study (SOSS) showed that after RYGBP, there is a regain of 10% of the TWL
  • The Longitudinal Assessment of Bariatric Surgery (LABS) showed a regain of 7% TWL (7 years after RYGBP)
  • Another study showed a regain of 12% TWL 12 years after RYGBP



Weight loss failure and weight regain after RYGBP


Weight loss failure is sometimes defined as inadequate total body weight loss (<25% TBW), inadequate excess weight loss (< 50% EWL) or BMI >35 after 5 years.


Insufficient weight loss or weight regain after a RYGBP may occur in 35% of patients.


Please note that all bariatric procedures have the potential for weight regain after 2 to 5 years. This is normal and is expected.


From experience and advice from many RYGBP surgeons, it has taught to us that the proximal gastric bypass procedure is the preferred technique, with a 50cm BP, 100-150cm AL.

  • Although increasing the BP limb length to 100-150cm is the most successful to reduce weight and achieve better resolution for medical co-morbidities (T2DM, hypertension and dyslipidaemia) but it also increases the malabsorption side effects.



Revision surgery after failed RYGBP


Revision surgery for weight regain after a standard proximal RYGBP may be complicated. The options may include:

  • Increasing the bilio-pancreatic limb length by shortening the total alimentary limb (TALL). This is probably the most simple option, converting the proximal RYGBP to a long BP limb RYGBP. This is done by removing the previous entero-enterostomy and redo the small bowel anastomosis about 100cm proximal from the ileo-caecal junction (this gives a minimal TALL of at least 250-300cm).
  • Increasing the bilio-pancreatic limb length by shortening the total alimentary limb (TALL). If the patient didn’t have a proximal RYGBP, if they already had a very long alimentary limb to start with, it can be converted to a long BP limb RYGBP. Similarly this is done by removing the previous entero-enterostomy and redo the small bowel anastomosis about 100cm proximal from the ileo-caecal junction (this gives a minimal TALL of 250-300cm). The second small bowel anastomosis is to increase the BP length to over 100cm.
  • Increasing the alimentary limb, to convert the proximal gastric bypass to a distal gastric bypass.
  • Convert the RYGBP to a bilio-pancreatic diversion with duodenal switch (BPD-DS). This operation requires restoration to a normal anatomy first before creating the BPD-DS from scratch. This procedure can be very difficult to perform in a revisional setting. It also may also have a higher complication rate for anastomotic leaks and strictures.




Some studies find that the first 2 revision options described above may result in about 40% EWL and a BMI drop of 10.


However increasing the malabsorption (with a TALL of 250cm) may result is serious side effects and complications, especially severe protein malnutrition (which may be in up to 30% of patients) and vitamin deficiencies. Thus these operations are rarely performed and is generally discouraged.



The final comment is really to remind patients that bariatric surgery is not about weight loss alone. To re-iterate


The aim of bariatric/metabolic surgery is to:

  • Achieve durable and maintained excess weight loss (>50% EWL)
  • Treatment (or resolution) of obesity associated co-morbidities (mainly Type 2 diabetes mellitus, hypertension, dyslipidaemia, sleep apnoea)
  • Improvement of quality of life (in a physical, social, family circles and emotional well being
  • Increase survival (life span)





Post op gallstone


Obese Caucasian female patients in the 30-40 years age group are more likely to have gallstones (even without having bariatric surgery).


After bariatric surgery the estimated incidence of developing gallstones may be 30-45%

  • The higher the weight loss result, the higher the risk (> 2 times) for developing cholesterol gallstones
  • This may be due to altered bile chemical composition (usually an imbalance between cholesterol, bile acids and lysolecithin)
    • After surgery the liver increase the secretion of cholesterol, reduce the secretion of bile salts and lecithin
  • Gallstone formation may be due to gall bladder hypomotility, increase nucleating factors for gall stones and change in the gastro-intestinal hormones after weight loss surgery
  • Genetic variation in the enzyme HMG Co-A reductase gene (which normally lowers LDL-cholesterol) may also contribute to gall stone formation


Perhaps up to 15% of patients develop symptomatic biliary colic within 2 years

Most people who develop biliary colic ends up having a cholecystectomy


Some patients take statin medications for high cholesterol

  • In theory statin medications may reduce the liver synthesis of cholesterol and may reduce gall stone formation
  • However it is uncertain whether these medications reduce gallstones or cholecystectomy rates
  • Similarly it is not certain whether ursodeoxycholic acid will help to prevent cholecystectomy




However complications such as common bile duct stones, obstructive jaundice and biliary pancreatitis can be very difficult to manage

  • After OAGB and RYGBP, a standard ERCP will not be possible due to the bypassed proximal small bowel and altered anatomy




Gastric cancer risk


In theory, in the long term there may also be a risk for gastric remnant cancer, which can’t be screened with gastroscopy because the stomach is excluded. We do not know whether this will be a common problem for our patients in Western societies..


Diagnosis is difficult, often delayed, the cancer is in the more advanced stage, treatment is more difficult and hence the prognosis is less favourable.