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Results for : "length of bowel"

Length of Bowel : Hess or No Hess

March 22, 2020 5:58 pm

“…What is the length of my common channel” is probably one of the frequently asked questions about the duodenal switch operation in the office. This usually comes up at the initial consult when patients repost credible sources such as Dr. Google and Dr. Facebook for patient with different bowel length have done well or not so after duodenal switch operation. Dr. Hess described the Duodenal Switch by using total bowel length measurements and creating the common channel as a percentage of the total small bowel length.  However, it seems that this is being done less and less.

This leads to my explanation that is on the website

Hess calculator : Bowel Length Calculator

How the actual measurements matters: Bowel length video link

In 2019, Bekheit published a very interesting study comparing total small bowel length (TSBL) to a number of variables such as height, weight, sex and BMI. They identified a few loose correlations. Male patient have longer TBSL than females. There was correlation between TSBL and height stronger in males than females but not statistically significant.

In Conclusion they reported ” Despite statistical significance of the correlation between the TSBL and the height and weight of the included participants, the correlation seems to have no clinical meaning since the effect size is negligible. ”

As I have previously discussed this  Making the common and alimentary length standard for every duodenal switch patient will make some loose too much and other not enough weight.

Figure 1 shows TSBL on the horizontal axis, and height, weight, BMI and Age on the vertical axis. For the most part what they all show is that one can not predict how long a patients bowel is by any of the measures that we take in the office as a part of the routine exam.

This raises, the concerns  that I had raised previously. How could two similar patients who have the same weight, age, sex and BMI have the same surgery and expect the same result if one of them has TSBL of 400 cm and the other one 800cm?

If both of the patients get the same “cookie cutter” duodenal switch with the same lengths, then the patient with TSBL of 400 will have much longer common channel if the surgeon does not customize the length of the bowel. This is an example of many patients whom we have revised over the years where they had a duodenal switch done with the “standard” 125cm common channel and when we measured the total length the patient had 500 cm TSBL.

Additional Links here.

Bowel Length Hess Calculator

July 06, 2016 10:50 am


Total Length (TL) cm:   

Alimentary channel length (AL) cm:   

Common channel (CC) cm:   

Dr. Ara Keshishian follows Dr. Douglas Hess’ procedure for calculating the limb lengths of Duodenal Switch. The following is Dr. Hess’ statement on measuring for Duodenal Switch limb lengths. Here is a blog post regarding Duodenal Switch limb lengths. Dr. Ara Keshishian discussing Duodenal Switch limb lengths in a video.

The proper measurements when performing the Biliopancreatic Diversion with the Duodenal Switch are very important for good long term results.  If the common channel is too long or the stomach is too large the patient may not have good sustained weight loss.  If the alimentary limb is too short the patient may not be able to absorb adequate protein and may require a revision. The patient must be able to eat, the duodenal stoma should not be small, but wide open, so the patient can take in protein.

We have measured the total small bowel length in more than 1400 patients we have operated and there is a large difference from the shortest (12 feet) to the longest bowel (38 feet).  You can see that one size does not fit all!  In our experience a common channel of 10% is the best size.  We use three sizes: 50 cm, 75 cm, and 100 cm whichever is the closest to the ten percent mark.  This way we have three sizes of  common channels and we can group them together to evaluate the lengths.  The length of the common channel determines the degree of malabsorption of fat.  You will, however, absorb enough fat for all the essential fatty acids needed for life.

The alimentary limb (the portion of small bowel which the food passes through) is formed nearest to 40% of  the lower part of the small bowel, always in increments of 25 cm (10 inches) from 250 to 350 cm as shown below.  The most common size used is 75 cm for the common channel and 275 cm for the alimentary limb.  For example: the common channel length is 100 cm in only 7% of our cases, 75 cm in  67  %,  and 50 cm in  23 %.  From this you can see we feel that using a 100 cm common channel is not correct in most cases.

We believe measuring the total bowel is very important for good long term results.

Category :

Bowel Length in Duodenal Switch

November 09, 2015 6:25 am

Malnutrition is one of the most feared complication of the duodenal switch operation. It may present years after surgery. What is common is a mix of nutritional deficiencies which include fat soluble vitamins, and protein calorie malnutrition. These all point to possible excessive shortening of the common channel. In my practice we have seen patients that have had lengthening of their common channel to improve their metabolic picture. What is very obvious to us, is that we see disproportionately higher number of cases coming to us for revision from practices where the common and alimentary lengths are done as a “standard” numbers with no specific adjustments made for the patient, their anatomy and situation. I have said for years, that the length of the bowel that is measured to be become the common and the alimentary limb should be a percentage of the total length of small bowel, rather than a pre-determined measurement. Here is a visual description of how this works.

If a common channel and the alimentary limb is measured to be a percent of the total length then the chance of protein calorie malnutrition is minimized since this will take into account the bowels absorptive capacity which is being reduced. This decrease in the absorption is done as a fraction of the total length.

Raines et al. published  a study in 2014, that showed how small bowel length is related more closely to a patient’s height and not weight.  And yet, some surgeons totally based the length of the common channel and the alimentary limb arbitrarily based on the patient pre operative BMI and nothing else. Could this be the cause of why I see some patients coming to us for revision of their duodenal switch for malnutrition?

Length of Small Bowel

October 26, 2009 2:49 am

It appears that there are series of questions and concerns that are not completely resolved, and they resurface every so frequently. Length of the small bowel for the Common Channel and the Alimentary limb in the Duodenal Switch operation is one of those topics.

The Questions that I am asked:

  • How long is my common Channel?
  • Another patient had the same length, but they are loosing more (or less) as the case may be.
  • I was told by another surgeon that they would give me a certain length of common channel, what do you think?

The common problem is that there is no accurate and practical way to measure the length of the bowel. There is also two schools of though, with very little objective research to support one or the other. There is no published data that I could find that answers this question head on. There are number of other
articles, and presentations that touch on this topic.

The best reference that I think is worth looking over is an editorial by Dr. Hess. The link is provided below.

I would like to discuss this in an organized way.

The artistic work is done by yours truly!

First a Brief over view of our GI track:


Our GI track starts at the mouth and ends in the rectum (figure 1). It is a long tube that has a very few side branches. These include the opening of the salivary glands in the mouth, the opening of the biliary (from the liver) and the pancreatic (from the pancreas) plumbing to in the first part of the small bowel
(duodenum) and the Appendix (at the junction of the small bowel and the large bowel).

Related article is available on our site.

The small bowel is the part that causes all this confusion. The small bowel is a long pliable, elastic tube that can be stretched (figure 2).


Depending on how much force is applied to it, it can be of different lengths. A similar analogy is the phone cord to head set of a conventional phone. The spiral cord placed on a table will coil up to a certain length. If one then pulls on two ends it will measure longer. And if more pull is exerted, then it will easure even longer. This demonstrates that the absolute measured length of the small bowel, is directly related to the force with which it is pulled. What this means is that if two individuals measure the length of the headset cord, or the bowel, they will get two different lengths, both correct but not the same. The length is directly proportional to the pull force applied to both ends.

Furthermore; the length of the small bowel is determinant of the absorptive capacity (amongst other factors). The longer the small bowel the more absorption, and the shorter the small bowel, the less absorption. There is a general-trauma surgical problem knows as short gut syndrome, where the length of the bowel is so short that it cannot support maintenance of the electrolytes and minerals, in additions to the required absorption of the calories. Short gut syndrome is a very difficult surgical problem to solve.

Getting back to our discussion however, we can now appreciate how two
surgeons can measure the same amount of small bowel (the same absorptive capacity) but end of with different lengths of small bowel. Same amount of bowel, same absorptive capacity, different lengths. This is why comparing lengths of small bowel is probably not the most accurate way to. Two patients, both with 75 cm common channels may have very different absorptive capacity, unless the bowel was measured by the same surgeon, and both patients had the same amount of total bowel length. We should next consider a possible alternative. Consider the drawing on (figure 3) and (figure 4).


The distance between C and B is 25% (quarter) of the total length between A and B. This represents a segment of bowel that was measured and marked Now lets take the same amount of bowel and apply a little more pull force to the ends while measuring it. We will have a total length of 80 cm, between A and B (figure 5). The distance between A and C will be 60 cm and the distance between C and B will be 40 cm (figure 6). The absolute lengths then are double of the first case. Same amount of bowel, same absorptive capacity yet double the length. Does this mean that the second patient with distance between C and B at 20 cm will absorb twice as much as the first patient? The answer is no, since it was the same amount of bowel that was measured with different technique.


Lets now however look at this from another perspective. In both cases the distance between C and B was only 25% of the total length.

Table 1
Distances Figures 3 & 4 Figures 5 & 6
Total length A-B 40 cm 80 cm
A-C 30 cm 60 cm
% of total 25% 25%

The table above shows why lengths of bowel discussed in-terms of percentage of total may be a more standardized than the absolute numbers.

In this example both patient will have same absorptive capacity (25%) yet will have much longer absolute lengths. In our practice, we measure the total length and the common channel and the alimentary lengths are based on the patient BMI, comorbidities, age, sex, and activity level.

Please remember that this is only my opinion, different surgeons do it differently.

Thyroid Medication Absorption And Weight Loss Surgery

June 10, 2019 8:59 am

Question : “Do I have to take higher dose of thyroid medication after the duodenal switch? ”

Answer : “Maybe”

With all weight loss surgical procedures, there may be changes to absorption of medications. It is easily understood why duodenal switch may results in decreased absorption of fat-soluble medication. What is not as clear is the reduction in absorption of other medication with procedures that do not explicitly change the absorption at the level of the small bowel directly.

The research data is all over on this topic. There is published literature that shows improvement in the thyroid function after gastric bypass and the sleeve gastrectomy.  However, the exact mechanism is not completely understood.

There is research that reports “…decreased postoperative levothyroxine requirements.” Other have shows no correlation between the length of the bowel distal to duodenum to absorption of thyroid medication.

With all this confusing data, the best course would be to always “treat the patient and not the lab results.”

If a patients who has been on medications with stable number and symptoms,  suddenly presents with complaints of hypothyroidism after weight loss surgery, it’s possible the medications should be up adjusted even if the thyroid lab values may not be as defining.


Candy Cane Gastric Bypass – RNY

June 21, 2018 1:05 pm

One of the findings following Gastric Bypass is a Candy Cane Gastric Bypass. Nausea and vomiting , upper abdominal pain is a common complaint of patient who have had the Gastric Bypass RNY operation. This is in addition to the high incidence of patients who experience the complications of weight regain and or dumping syndrome.

Quite frequently the symptoms of nausea, vomiting and upper abdominal pain of a patient with history of gastric bypass is evaluated by a primary care, referred to a gastroenterologist. The “routine” work up recommended is X-ray of the abdomen, maybe contrast study (Ct scan or upper GI) and for sure and upper endoscopy. The result quite frequently reported as “…nothing wrong”.

A typical upper GI in a Candy Cane Gastric Bypass situation may look like this:

Upper GI

A common and underreported problem may be a Candy Cane finding. The “blind” end of the small bowel anastomosis is too long and this results in food settling in the hook of the candy cane. The symptoms of the nausea, vomiting and upper abdominal pain may be from the residual food and liquids that do not drain from this area.


Candy Cane Gastric Bypass finding


Candy Cane Gastric Bypass cases will require surgical intervention to shorten the length of the blind segment of the small bowel to improve symptoms.

It is my recommendations that any patient with history of weight loss surgery who is having any persistent gastrointestinal symptoms be evaluated by weight loss surgeon.

Standard Common Channel In Duodenal Switch Will Result In Weight Regain.

December 16, 2016 1:57 pm

Stéfane Lebel, M.D.*, Geneviève Dion, M.D., Simon Marceau, M.D., Simon Biron, M.D., M.Sc., Maud Robert, M.D., Laurent Biertho, M.D. earlier this year released a research article comparing patients undergoing standard common channel of 100cm and standard common channel 200cm. The conclusion of this article was: “In this population, BPD-DS with a 200-cm common channel offered similar remission rate of co-morbidities compared with standard BPD-DS. It was associated with similar weight loss at nadir, followed by a more significant weight regain. It might yield a lower rate of nutritional complications. Long-term randomized data are needed to detect other potential advantages.”

Our Experience:

One of the most dreaded outcomes of any weight loss surgical procedure is weight regain. This is assuming that initial adequate weight was lost to result in resolution of the co-morbidities in the first place.  As the weight loss surgical field has changed over the years so has been the cases of regain that we have seen.

There was a time when Lap bands were being revised for inadequate weight loss and weight regain. Not to mention the complications of reflux, difficulty swallowing and persistent Nausea and vomiting. Then as more Gastric bypass procedures “aged” the number of patients that started looking for revision for weight regain increased. The latest fad is the Vertical Sleeve Gastrectomy that are done with false sense of expectation and results. The long term outcome of Vertical Sleeve Gastrectomy is no where close to that of the Duodenal Switch, independent of the size of the sleeve. In fact, more surgeons are trying to get a little more weight loss by making the sleeve too tight. All they are doing is creating a significant and debilitating set of problems such as reflux, nausea, and solid intolerance.

The ideal revisional procedure for these patients should be the Duodenal Switch. Some surgeons, however, have started advocating “single anastomosis” knock off the duodenal switch. Others do “standard length common channel” rather than a Hess method Duodenal Switch. I have always performed a traditional Hess method Duodenal Switch.  The Hess method Duodenal Switch has held the largest and longest excess weight loss maintenance for 28 years, going into 29 years.  Here is a past blog regarding small bowel length.

The predetermined standard common channel results in weight regain. Study


Duodenal Switch

August 24, 2016 5:45 am

Buyer Beware ! There are a lot of look alike and counterfeit “Duodenal Switch” procedure being performed. A recent online chat discussion clearly demonstrates the point that just because a patient is told that they had the duodenal switch operation this is not necessarily the case.

In our practice, we always warn our patients of not comparing notes and their outcome to others. I perform the Duodenal Switch procedure  the way it was described by Dr. Hess, making the common and alimentary lengths as a percentage of the total length of small bowel. This is why our patient population has very little nutritional, and gastrointestinal issues compared to others. Unfortunately when a patient is given a disproportionately long Common channel and/or Alimentary channel the patient will have inadequate weight loss. Alternatively, when patients are  given a shorter alimentary channel in proportion to the total bowel length, significant nutritional deficiencies can arise. In a shorter alimentary channel situation patients have to consume higher doses of vitamins and nutrients to keep their laboratory values normal.

I have repeatedly raised the issues to clearly distinguish the single anastomosis procedures from Duodenal Switch operation.

One of the unfortunate problems is the lack of clear guidance given to the patients. It is not uncommon, when I do second opinion consultation with patient who were given generic gastric bypass post op protocol and instructions after their duodenal switch operation. This clearly shows lack of fundamental understanding of the practice performing these procedures and it is carried onto the patient.