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Length of Bowel : Hess or No Hess

Posted On : March 22, 2020

“…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 et.al 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.

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