The original bariatric procedures came from the fact that patients who underwent gastric resection subsequently lost weight. Additionally, it was known that the intestine was adaptable, but at a certain level, when shortened, weight loss would occur. Thus, the issue became whether these concepts could be titrated and balanced to offer those with severe obesity procedures that would effectively allow them to lose weight and not become malnourished or symptomatically micronutrient deficient.

Edward Mason, who performed the first gastric bypass for obesity, argued that any manipulation of the bowel would result in an unacceptable rate of anemia and bone loss and only gastric reduction procedures should be performed [4]. The alternative viewpoint was that gastric-only procedures would not allow the majority of patients to reach their weight loss goals. Many would develop a maladaptive eating pattern that would limit surgical effectiveness. Furthermore, gastric restriction has been plagued by ulcers, strictures, esophageal dysfunction, and decreased satisfaction with eating and choice of food. This debate remains a sentinel issue in bariatric surgery. Whether vertical banded gastroplasty versus gastric bypass or, in the laparoscopic era, gastric bypass versus adjustable banding and now sleeve gastrectomy, gastric-only procedures reduce the risk of the manifestations of short bowel syndrome. The cost is that they also do not offer the intestinal mechanisms that help cause weight loss.

By definition, every bariatric procedure produces an abnormality. The more the anatomy is altered, i.e., the more stomach removed and intestine bypassed, the greater the weight loss. The corollary of this statement is that the more that is altered, the greater the chance of nutritional deficiency. How these factors are balanced in aggressive operations that add an intestinal component is the emphasis of this chapter. We realize that our operations are more than the sum of making the stomach smaller and the intestine shorter. However, while we know that radically shortening bowel length causes weight loss, albeit with unacceptable side effects, we do not know exactly what our shorter bypass lengths do. Additionally, little is known about what the ideal lengths should be for a Roux limb, biliopancreatic limb, or common channel. Few meaningful studies have evaluated these issues. A recent systematic review of short versus long Roux limb length examined a total of eight studies. A trend was identified supporting the early efficacy of longer Roux limbs in the super obese patient category. However, the authors questioned the overall quality of the data due to inconsistent data reporting [5].

What are the most important variables? It would seem that the total intestinal length in contact with food and the common channel length are critical factors. In traditional gastric bypass, both of these values vary between patients and certainly between centers. Despite this, reported results seem to be consistent, thus further adding to our need for knowledge and understanding about what happens when an intestinal bypass is added to a gastric restriction (with or without pyloric preservation).

For the intestinal component there are several points that must be remembered from the knowledge obtained from the JIB and early bariatric procedures:

Dr Nicolai Scopinaro, an Italian surgeon and pioneer in bariatric surgery, hoped to modify the JIB and develop an operation that would be lasting. Dr Scopinaro believed that a significant amount of intestine needed to be bypassed to allow for weight loss. The window was narrow, and the intestines’ ability to hypertrophy and increase its absorptive surface was substantial. Furthermore, he believed that gastric restriction would be fleeting and if there was not an intestinal component causing malabsorption, considerable weight regain was inevitable. After adjustment, meal size would increase and recidivism would occur. Scopinaro hypothesized that significant weight loss would need to be achieved in the first year. During this period of time, consumption would increase and the bowel would hypertrophy. Thus, there would be a narrow window between bypassing too much bowel and enough bowel to have impact as the intestine adapted.

Scopinaro thus decided to combine a gastric resection with an aggressive intestinal bypass (Fig. 3) [6]. There have been different variations and even alterations depending on eating behavior or whether the patient was from Southern or Northern Italy. The operation involved a distal gastrectomy preserving between 250 and 400 cc of gastric volume. The fundus thus was preserved at the angle of His. The small bowel was measured from the terminal ileum for 250 cm then divided. The biliopancreatic limb was reattached 50 cm from the colon. In certain patients, the intestine was divided 300 cm from the ileocecal valve. There were many differences between the Scopinaro procedure and the JIB. Total intestinal length was increased from 0.5 to 2.5 to 3 m. Bile could be absorbed throughout the entire biliopancreatic limb, reducing the impact of bile salts on the colon. The distal gastric resection reduced the amount of food eaten following surgery and reduced acid secretion, allowing attachment of the small bowel to the stomach.

In 1998, Scopinaro reported a 21-year experience with the biliopancreatic diversion in 2,241 patients with a mean BMI of 47 kg/m² (range 29–87 kg/m²) [7]. Mean reduction of initial excess weight was 75 % with a follow-up rate of 98 %. Additional beneficial effects of biliopancreatic diversion included improvement or resolution of hypertension, fatter liver, leg stasis, hypercholesterolemia, diabetes mellitus, hyperuricemia, and gout. Furthermore, there is an in-depth analysis on the eating behavior and the amount of food that is actually absorbed by patients years from surgery.

According to Scopinaro, weight loss occurs in the first year following surgery, and the intestinal bypass allows that weight loss to be maintained. In the first several months following surgery, intake is a significant challenge, even with what would be considered large gastric pouches. Ghrelin and other gut peptides were not known at the time of this report, but Scopinaro believed that much of the symptomatology came from intestinal distension following eating or postcibal syndrome. Over the course of the first year, this symptom disappeared, and meal size approached preoperative levels.

Therefore the intestinal bypass caused weight loss to last more than 10 years after surgery. Scopinaro measured absorption of different food groups in patients that reached weight stabilization. 57 % of total energy was absorbed. Only 27 % of fat was absorbed. Virtually 100 % of simple sugars would be absorbed and approximately 60 % of total protein. Additionally Scopinaro pointed out that protein, starch, and carbohydrate percentage absorption would be affected by the total length of intestine in contact with food. Only fat absorption would vary with common channel.

Another contribution to the literature from this report was the concept that the intestinal bypass actually increased energy expenditure. Detailed analysis in this report demonstrated that, compared to controls with similar weight loss and size, resting energy expenditure decrease was lower than would be expected in the surgical group. Recently, Kaplan highlighted that this, not malabsorption, is the significant contribution in an experimental model of gastric bypass [8].

Of course the BPD was not without issue. There was a 2 % rate that required reoperation for protein malnutrition. Scopinaro highlights that the likelihood of this increases if patients consume excessive carbohydrates. When that occurs insulin is stimulated which results in an increased amount of endogenous protein breakdown exacerbating the protein deficiency. During the first year frequent bowel movements are common, which are reduced to 2–4 more than a year following surgery. The marginal ulcer rate reported was greater than 8 %. Deficiencies of the fat-soluble vitamins and iron exceed 25 %. Calcium deficiency and bone demineralization can occur. Scopinaro shows that this stabilizes. Countering these adverse effects, there was a 100 % resolution of diabetes and hypercholesterolemia.

In summary, there is much that can be learned from this incredible data set. Obviously, the long-term data was quite impressive. Yet, there are many reasons why this operation did not expand in popularity and become an international standard. The list of side effects was numerous. In the setting of 100 % follow-up, many of these could be simply handled. In the United States and many other places, this level of follow-up cannot be expected. Furthermore, the duodenal switch, which reduced the marginal ulcer rate to near zero, became the preferential method for the performance of a biliopancreatic diversion. Even with this adaption and potential improvement, duodenal switch and other forms of BPD represent a small minority of bariatric procedures currently performed.

In 1998, Dr Douglas Hess became interested in the research of Dr Thomas DeMeester on duodenal gastric reflux and his concept of attaching a small segment of duodenum to the Roux limb of the small bowel. Hess wanted to utilize a similar approach to Scopinaro on revisions but encountered dense adhesions and, following these challenging revisions, a high rate of marginal ulceration. As a result, Hess developed the concept of combining a vertical gastrectomy of the greater curvature with a duodenal division preserving a small cuff of the duodenum.

Hess calibrated his gastrectomy using a 40 Fr bougie or dilator. The length of the small bowel was determined by measuring the total intestinal length from the stomach to the cecum. Then, 40 % of the total length was used to create the alimentary limb, and 10 % of the total length to create the common channel [9].

Advantages of the duodenal switch include preservation of the pylorus and the reduction of marginal ulcer rates. In a 1998 report, Hess reported an 85 % excess weight loss with 10 of 440 patients requiring revision for either protein malnutrition or diarrhea. The duodenal switch has become the most common version of biliopancreatic diversion. Within North America, Dr Gary Anthone [10] and Drs Marceau and Biron [11] have published extensive series with lengthy follow-up. In contrast, to Hess, they have used fixed bowel length rather than calculating based on total intestinal length.

In the late 1990s and early 2000s, bariatric surgery rapidly increased in popularity. The increasing obesity epidemic, combined with the development of laparoscopy, led to this growth. With the movement to laparoscopy, techniques were developed to perform the duodenal switch in a minimally invasive nature.

The first major report of laparoscopic duodenal switch came from Ren and Gagner [12] in 2000. This report discussed their technique for laparoscopic bypass and highlighted an increased complication rate for those with a BMI greater than 60. It was the basis of this study that made Dr Gagner postulate that staging the procedure and doing the vertical gastrectomy and then following weight loss proceed to the intestinal bypass. Interestingly, despite the fact that Scopinaro always felt that the gastric aspect caused much of the early weight loss, many trained in North America felt that in BPD the major component was from the intestine. Now with sleeve gastrectomy accepted as a stand-alone weight loss procedure, it is clear that the gastric resection is an important, if not dominant, component.