Long-Term Outcome of Isolated Duodenal Transit Bipartition as Initial Metabolic Surgery: A 19-Year Follow-Up Case Report

Introduction

Metabolic and bariatric surgeries (MBS) have gained widespread popularity and trust due to their proven efficacy and safety in managing not only obesity but also its associated comorbidities, such as diabetes mellitus, hypertension, dyslipidemia, sleep apnea, and joint pain [1].

MBS in patients with morbid obesity (Class III obesity), particularly in super-obese individuals, is challenging due to the inherent risks associated with this patient population [2,3]. In such cases, intraoperative technical difficulties, early surgical complications, and insufficient long-term weight loss are frequently observed [4–6].

Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy have been the most commonly utilized techniques. However, the best outcomes have been reported with so-called hypoabsortive procedures. Although biliopancreatic diversion with duodenal switch (BPD-DS) achieves superior weight loss and glycemic control compared to other techniques, its greater technical complexity, as well as the resulting gastrointestinal symptoms and long-term nutritional risks, have limited its widespread application [6].

A deeper understanding of gastrointestinal physiology and its relationship with metabolic pathways challenges the classical mechanisms of restriction and/or hypoabsorption. The effects of techniques such as BPD-DS can be explained by neuro-hormonal modulation, alterations in the gut microbiota, and changes in bile salt metabolism resulting from intense and early distal intestinal stimulation, with hypoabsorption being an unnecessary and avoidable side effect. This understanding has enabled surgical models to be modified with the aim of developing what is now referred to as pure metabolic surgery [6,7].

One of these surgical models proposes the concept of transit bipartition, which aims to achieve only partial deactivation of the proximal intestine while providing intense and early stimulation to the distal intestine. Its efficacy appears to be comparable to that of the classic BPD-DS [8,9]. Furthermore, the preservation of partial food flow through the duodenum provides nutritional protection by ensuring full access to the digestive tract, maintaining proximal protective mechanisms against hypoglycemia, and preserving the capacity for micronutrient absorption [6,10].

The objective of presenting this case is to demonstrate the feasibility and long-term outcomes of isolated duodenal transit bipartition when sleeve gastrectomy is not viable, as well as the feasibility of performing the first stage of MBS in the face of adverse intraoperative circumstances. In the reported case, the intestinal stage of the duodenal switch was performed without duodenal exclusion, utilizing the concept of intestinal transit bipartition at the duodenum. The gastric phase (sleeve gastrectomy) was not performed due to the inability to access the esophagogastric junction as a result of hepatomegaly [11]. Despite having undergone only 1 stage of the technique, the patient lost 50 kg and maintained the weight loss over 19 years of follow-up.

Case Report

A 40-year-old female patient sought medical care at the Instituto Paulo Reis in Goiânia, Goiás, Brazil, for bariatric surgery. At the time, the patient weighed 115 kg, was 1.69 m tall, had a BMI of 40.2 kg/m2, and presented no obesity-associated comorbidities. The patient met the criteria for bariatric surgery, and the duodenal switch technique was proposed. At that time, the institutional preference for patients with a BMI greater than or equal to 40 was for surgical techniques with a greater malabsorptive component, such as the duodenal switch. Additionally, it is important to note that in 2005, Brazil established its first regulation for bariatric surgery. This regulation did not establish specific criteria for selecting surgical techniques based on BMI. Consequently, the choice of procedure was primarily influenced by the surgeon’s experience with the available techniques. Despite this, it is well recognized that a patient with a BMI of 40.2 kg/m2 is classified as having grade 3 obesity (morbid obesity), therefore meeting the eligibility criteria for bariatric surgery, even in the absence of other comorbidities. This justifies both the indication for surgery and the use of the chosen procedure, the duodenal switch.

Preoperative examinations were requested, and the patient was prepared for surgery under the supervision of a multidisciplinary team. Following the completion of preoperative evaluations and approval by the multidisciplinary team, the surgery was scheduled. We emphasize that, in our routine practice, the preoperative workup includes blood tests, imaging studies, cardiological evaluations, and other specific examinations tailored to each patient’s particular conditions. The medical team routinely requests ultrasound for all patients and documents both the identified comorbidities and any abnormalities found in the preoperative exams. In this case, as there are no records of any abnormalities in the ultrasound, it is clarified that the examination did not reveal any significant findings. It is also important to highlight the inherent limitations of ultrasonographic evaluation, including its dependency on the expertise of the physician performing the assessment.

During the initial phase of the abdominal approach, hepatomegaly was identified, which hindered safe access to the esophagogastric junction and rendered the completion of one of the stages of the duodenal switch, the vertical gastrectomy, unfeasible. Given this challenge, the decision was made to perform only the intestinal component of the procedure: a duodeno-ileal anastomosis. This was deemed a temporary solution to assist the patient in weight loss, with the plan to complete the procedure with a vertical gastrectomy 12 months later.

Due to the difficulty of accessing the duodenum, which had friable and hemorrhagic mesentery, a modified duodenal switch procedure was performed, involving intestinal transit bipartition at the duodenal level. The bleeding complicated the technical aspects of the procedure; however, despite the absence of an estimated blood loss evaluation, it did not affect the patient’s hemodynamic stability. This was because the bleeding originated from small mesenteric vessels, and was successfully controlled using energy devices. A duodeno-ileal anastomosis was performed on the first portion of the duodenum, without exclusion, to simplify the surgical procedure at that time. The manual 4-cm laterolateral duodeno-ileal anastomosis was performed in a single-layer suture with reinforcement at the angles of the anastomosis was created in the first portion of the duodenum (duodenal bulb), without duodenal transection, 250 cm proximal to the ileocecal valve, utilizing a single anastomosis technique (one anastomosis) as proposed in the Single Anastomosis Duodenal Ileal Bypass with Sleeve gastrectomy (SADI-S). However, in SADI-S, the duodenum is septated (Figure 1) [12]. It is worth emphasizing that this was the first duodenal transit bipartition performed at our institution. The patient was discharged on the second postoperative day without complications, and the total time for the surgical procedure was approximately 2 hours.

After 12 months, the patient showed successful weight loss, and the medical team, in agreement with the patient, determined that there was no need to perform the vertical gastrectomy at that time. Currently, after 19 years of follow-up, the patient is 59 years old, has lost 50 kg, and has a BMI of 22 kg/m2. The excess weight loss was 78.7%, indicating that the surgery was successful [13]. Table 1 summarizes the patient’s characteristics, and Table 2 presents the results of follow-up laboratory tests.

During this period, the patient reported complaints of gas and infrequent episodes of meteorism and diarrhea, primarily associated with the consumption of fatty foods – common occurrences in patients undergoing this type of surgery. These issues were managed with clinical treatment and nutritional guidance. The patient reported reduced food intake due to increased satiety during meals, with a bowel frequency twice daily and stools of normal appearance. However, adherence to vitamin and protein supplementation remains challenging for the patient.

Discussion

METABOLIC RATIONALE:

MBS has proven to be an effective and safe treatment for obesity. While the surgical principles of gastric restriction and/or gastrointestinal bypass (malabsorption) have remained largely unchanged, advances in the understanding of energy balance and appetite regulation have clarified additional mechanisms, including the role of entero-hormones. These hormones, released in response to adaptive changes in the gastrointestinal tract, are central to satiety mechanisms [14,15].

The ileum plays an important role in this process; when food reaches this distal segment earlier, it stimulates the release of GLP-1 and PYY, promoting satiety [16]. Additionally, the diversion of bile to the ileum enhances secretion of FGF-19 and L-cell products, amplified by intestinal hypertrophy [17]. Studies show that bile diversion replicates the beneficial metabolic effects of RYGB, including improved glucose metabolism, reduced hepatic glucose production, and augmented intestinal gluconeogenesis. It also regulates eating behavior by decreasing interest in high-fat foods, supporting weight loss [18,19].

The preservation of both the stomach and duodenum, combined with the partial diversion of intestinal transit, balances metabolic benefits with improved nutrient absorption. This mechanism reduces the risk of small intestinal bacterial overgrowth (SIBO) and strengthens the concept of “ideal surgery” or “pure metabolic surgery” [20,21].

SURGICAL FEASIBILITY:

As previously noted, MBS in morbidly obese patients, particularly super-obese individuals, is technically challenging and involves increased perioperative risks [2–6]. In such cases, 2-stage approaches have been adopted for procedures like the duodenal switch, gastric bypass, and post-band revision surgery to mitigate complications [22–24].

Duodenal transit bipartition combined with sleeve gastrectomy has been widely practiced using stapled laparoscopic anastomoses and, more recently, magnets [25–28]. In cases involving severe obesity with hepatomegaly, where upper abdominal access is challenging, isolated intestinal transit bipartition may precede sleeve gastrectomy to reduce risk, deferring the definitive procedure until weight loss is achieved [6,7].

In the case presented here, duodeno-ileal anastomosis was performed as the initial step due to challenges posed by hepatomegaly and morbid obesity, while preserving the stomach and avoiding intestinal exclusion. This simplified approach has enhanced surgical safety, particularly in complex cases, and has also been explored in procedures such as SADI-S [26–29].

LONG-TERM OUTCOMES:

This strategy did not compromise long-term weight loss outcomes. Sustained weight loss over 19 years indicates the durability of neuroendocrine mechanisms, as food reaches the distal intestine earlier, inducing satiety and metabolic benefits [30,31]. The preserved stomach allows for a potential second-stage sleeve gastrectomy, if required, to enhance metabolic effects [6,23].

The literature consistently reports significant improvements in quality of life (QoL) following various MBS procedures, with noticeable gains within 3 months after surgery. By 18 months, patients’ QoL often reaches levels comparable to the general population [32–34].

The patient in this report showed favorable progress, including significant weight loss and satisfactory laboratory test results to date. While this approach was initially chosen to overcome technical challenges during surgery, it successfully facilitated postoperative weight loss with the advantage of a second-stage option, which has not yet been necessary.

Conclusions

MBS is widely recognized as a safe and effective treatment. However, in patients with morbid obesity, special strategies may be necessary to ensure greater safety, particularly in cases involving technical difficulties during intraoperative gastric approaches. Performing the procedure in 2 stages may be an exceptional alternative for this population of patients who present technical challenges during the intraoperative surgical approach. In the case presented, duodeno-ileal anastomosis resulted in effective weight loss, with sustained results over 19 years of follow-up, without the need, so far, to proceed with the second stage of surgery to address the stomach.

Based on these long-term follow-up results, it can be concluded that isolated duodenal transit bipartition, performed with duodeno-ileal anastomosis without duodenal exclusion, represents a promising alternative in exceptional cases. In this article, we present the longest follow-up result of the first duodenal transit bipartition performed with the purpose of weight loss, proposing a 2-stage bariatric approach. However, we emphasize the limitation of this study, as it describes only a single case. This approach is technically “simple”; however, as the satisfactory results are based on a single case, further studies are required to strengthen the evidence base for its indication, safety, and efficacy. In the future, with additional research, it may also be considered an initial treatment option for patients with lower BMIs, with or without type 2 diabetes.