Introduction

Obesity is a worldwide crisis that profoundly affects health, quality of life, healthcare systems, and the global economy, establishing it as a critical issue for governments and policymakers1,2,3. According to the Centers for Disease Control and Prevention report, the prevalence of obesity in the United States was 41.9% from 2017 to 2020. Additionally, the incidence of severe obesity rose from 4.7% to 9.2% in this period4. The National Center for Health Statistics anticipated that one in four adults in the U.S. will suffer from severe obesity by 20305.

Metabolic and bariatric surgery (MBS) has become a key treatment for severe obesity, offering significant weight loss, improvement in obesity-associated medical problems, and enhanced the quality of life of and eating behaviors of the patients6 (7. Roux-en-Y gastric bypass (RYGB) is the second most widely performed bariatric surgery, after sleeve gastrectomy (SG). It is particularly effective for significant weight loss and management of obesity-associated medical problems like type 2 diabetes mellitus (T2DM) before weight loss achievement through changes in gastrointestinal hormones secretion8,9.

The adoption of laparoscopic techniques in the early 1990s represented a major shift from traditional open surgeries to minimally invasive methods, enhancing safety and reducing recovery times10. This advancement led to the widespread adoption of laparoscopic gastric bypass, subsequently increasing the number of individuals undergoing MBS. However, gastric bypass surgeries can lead to serious complications, such as leaks, obstructions and subsequent anastomotic strictures due to marginal ulceration, or pouch dilatation. Marginal ulceration at the gastrojejunostomy site is an important complication of RYGB with an incidence rate of approximately 4.6%11 that may lead to bleeding, perforation and stricture12.

Anastomotic leak is a serious complication that significantly increases mortality (14% vs. 4%) and lengthens hospital stays (24.5 vs. 4.5 days) compared to patients without it13. RYGB can be associated with early dumping and postprandial hyper-insulinemic hypoglycemia, an increasingly recognized complication, known as late dumping14.

RYGB, typically has a gastric pouch volume between 20 and 60 mL, depends on the surgical technique variations15,16. Smaller gastric pouch sizes may restrict food intake more, facilitating quicker weight loss and better weight maintenance and food tolerance post-surgery16. The gastric pouch size is crucial in determining how quickly food moves from the stomach to the intestines, affecting the procedure’s efficacy in terms of weight loss outcomes and patient satisfaction17. Gastric pouch size may also affect certain obesity-associated medical problems. But in the other hand, the stoma size at the gastrojejunostomy may have a crucial role in slowing the gastric emptying and incidence of early dumping syndrome.

This study aims to compare the weight loss outcomes and complications after long gastric pouch versus short gastric pouch RYGB in patients with severe obesity in two university hospitals in Tehran, Iran.

Methods

This retrospective study was conducted from January 2020 to December 2021 at Firoozgar Hospital and Hazrat-e Rasool Hospital in Tehran, Iran, adhering to the ethical standards of the Helsinki Declaration ethical standards.

Ethics approval for this study was obtained from the Iran University of Medical Sciences ethics committee (IR.IUMS.FMD.REC.1401.272). Written informed consent was obtained from the participants in this study.

Participants

The study included patients who underwent RYGB surgery during 2020 and 2021. The inclusion criteria were according to the previous NIH guidelines including adults aged 18–65 diagnosed with severe obesity (BMI ≥ 40 kg/m2, or ≥ 35 kg/m2 with obesity-associated medical problems). Patients with prior upper gastrointestinal surgery, contraindications for RYGB, or incomplete medical records were excluded. All included patients underwent Esophagogastroduodenoscopy (EGD) at one year after the surgery. Early dumping syndrome (DS) were evaluated using Sigstad’s scoring system and a score above 7 was suggestive for DS18.

Data collection

Data were gathered retrospectively from Iran National Obesity Surgery Database (INOSD)19. This included baseline demographics, preoperative medical conditions (such as T2DM, hypertension, and obstructive sleep apnea), and surgical details. Postoperative metrics for complications after surgery and follow-up data at 12 months included, BMI, weight, EGD findings, and remission/improvement of obesity-associated medical problems including T2DM, HTN, DLP, OSA and GERD.

Outcome definitions

Patients were evaluated by follow-up EGD for gastroesophageal reflux disease (GERD), esophagitis, marginal ulcer and hiatal hernias by one gastroenterologist. According to the last Lyon consensus, patients with GERD more severe than GERD-A were regarded as GERD-positive in endoscopy20. Total Weight Loss (TWL%) was measured as: Weight loss after surgery (kg)/initial weight (kg) × 100. Remission of obesity-associated medical problems were defined based on the American Society for Metabolic and Bariatric Surgery (ASMBS) Outcome Reporting Standards21 as following:

T2DM (Complete remission: HbA1c < 6%, FBG < 100 mg/dl in the absence anti-diabetic medications; Improvement: reduction in HbA1c and FBG (not meeting the criteria for remission) or decreased need for anti-diabetic medication).

HTN (Complete remission: being normotensive without any antihypertensive medication; Improvement: A reduction in the dosage or quantity of antihypertensive medications, or a decline in either systolic or diastolic blood pressure while maintaining the same medication).

DLP (Complete remission: achieving a normal lipid profile without the use of medication; Improvement: reduction in the dosage of lipid-lowering medications while maintaining comparable management of dyslipidemia or achieving better lipid control with the same medication).

OSA (Complete remission: in those patients with preoperative polysomnography (PSG) with a diagnosis of OSA, an AHI/RDI of o5 off CPAP/BIPAP on repeat objective testing with PSG; Improvement: self-discontinued use of sleep apnea treatment CPAP/BIPAP due to improved symptoms).

GERD (Complete remission: Absence of symptoms and the absence of any medication usage; Improvement: Alleviated severity or frequency of symptoms, or diminished use of medication or only when required).

Surgical techniques

Both long and short-pouch gastric bypass surgeries followed standard protocols. The process began with identifying the Ligament of Treitz. A 125-cm segment from this ligament was marked. A surgical tunnel was created above the second left gastric artery branch using Harmonic scalpel in the short pouch group; in the long pouch group this tunnel was created at a point between the 3rd and 4th left gastric branch (Fig. 1). The short gastric pouch was made by firing two 60 mm Endo GIA stapler (one horizontal and one vertical, estimated volume = 30 cc). The long gastric pouch was made by firing one horizontal 45 mm Endo GIA stapler and two vertical 60 mm staplers over a 36Fr bougie (estimated volume = 80 cc). The jejunum was attached to the pouch using a 45 mm stapler with a stoma size of 25 mm in both techniques and the enterotomy was closed by 2.0 Maxon sutures. A 75-cm Roux limb was created, and a jejuno-jejunostomy was created using a 45 mm white stapler achieving the Roux-en-Y configuration. A Methylene blue test was done for anastomosis leak. The operation concluded by repairing Petersen’s space and jejuno-jejunal mesenteric space defects. Patients were categorized based on the technique of pouch sizes.

Fig. 1
figure 1

Diagram of short pouch and long pouch roux-en y gastric bypass. LG: Left gastric artery

Full size image

Statistical analysis

Data were analyzed using IBM SPSS Statistics software, version 26. Continuous variables were presented as mean ± standard deviation and categorical variables as counts (percentages). The chi-square test and t-test were used for comparisons between the two surgical groups, with a p-value < 0.05 indicating statistical significance.

Results

The study included 219 patients who underwent RYGB surgery, divided into two groups: 107 with long gastric pouches and 112 with short gastric pouches. Baseline characteristics of these participants are shown in Table 1. The average age was 41.90 ± 11.02 years and the average weight was 115.90 ± 14.74 kg. The mean Body Mass Index (BMI) was 44.12 ± 4.66. A majority of the patients were female, accounting for 194 individuals (88.58%). The prevalence of underlying diseases included 41 patients (18.72%) with T2DM, 43 patients (19.63%) with hypertension (HTN), 36 patients (16.44%) with dyslipidemia (DLP), and 33 patients (15.07%) with obstructive sleep apnea (OSA). Thirty-eight (17.35%) patients had GERD symptoms. No significant differences were observed between the two groups before RYGB.

Table 1 Baseline characteristics of the patients undergoing long and short pouch roux-en y gastric bypass.
Full size table

At 12-month follow-up point, substantial weight loss was noted in all participants. Reduction in BMI and TWL%, were more pronounced in patients with short pouches, however, neither reached a statistically significant p-value (p = 0.07 and 0.06, respectively) (Table 2).

Table 2 Weight metrics at 12 months in patients undergoing long and short pouch roux-en y gastric bypass.
Full size table

There was no statistically significant difference in the remission of T2DM, HTN, DLP, OSA, or GERD symptoms between the short and long gastric pouch RYGB groups (Table 3). For T2DM, 42.9% of the short pouch group achieved complete remission compared to 70.0% in the long pouch group (p = 0.202). Similarly, the remission rates for HTN (p = 0.657), DLP (p = 0.601), OSA (p = 0.063), and GERD symptoms (p = 0.118) were not significantly different between the two surgical approaches.

Table 3 Remission of underlying diseases 12 months after the surgery in patients undergoing long and short pouch roux-en y gastric bypass.
Full size table

The occurrence of erythematous gastritis was 26.2% in the long pouch group and 23.2% in the short pouch group (p = 0.960). GERD esophagitis was reported by EGD in 15% and 12.5% of patients in long and short gastric pouch groups respectively (p = 0.64) (Table 4), although remission and improvement of pre-existing GERD symptoms were reported by 100% and 86.4% of patients in long and short gastric pouch RYGB groups, respectively (Table 3). Neither marginal ulcers nor leaks were reported in either group (p = 1). Early dumping syndrome was identified using Sigstad’s scoring system in 41 patients (18.72%), with no significant difference between the short and long gastric pouch groups (p = 0.476) (Table 4).

Table 4 Endoscopic findings at 12 months after surgery, in patients undergoing long and short gastric pouch RYGB.
Full size table

Discussion

MBS is a safe and efficient intervention for individuals with severe obesity, offering a potential solution for weight loss and the management of obesity-associated medical problems. In the united states, the annual rate of MBS surged form, 59.2 to 71.6 surgeries per 100,000 adults in the last 10 years1. Following SG, RYGB is the second most common surgery performed1. In an experienced hand with an at least 75–100 procedure as learning curve22, RYGB is a completely safe and effective MBS to address obesity and its associated medical problems. RYGB is considered the most effective bariatric procedure for treating GERD2. A systematic review and meta-analysis found the odds ratio for GERD remission was 3.16 times higher for RYGB compared to SG2. Although nutritional deficiencies may be an important issue after RYGB such as other MBS procedures23, it has been demonstrated that long-term nutritional deficiencies including anemia and ferritin and B12 deficiencies are seen even in pure restrictive procedures such as SG24.

Traditionally, RYGB involves creating a short pouch (20–60 cc) in the upper part and rerouting it to the small intestine. In addition to the standard technique, surgeons have experimented variations of the standard RYGB. Long gastric pouch RYGB contains a pouch that can hold more (50–150 cc), with the hope of achieving better weight loss and even managing blood sugar levels more effectively compared to the traditional method3.

Ren Y et al. found that in patients with T2DM and a BMI of 30–35 kg/m2, smaller gastric pouch sizes in RYGB surgery correlated with greater weight loss and a higher percentage of total weight loss than larger gastric pouch sizes. This underscores the importance of customizing pouch size based on individual patient characteristics and health conditions15. Comparative studies are essential for evaluating these variations and identifying the optimal pouch dimensions for different patient groups25. The impact of pouch size remains unclear, with some studies showing significant correlations with weight loss outcomes, while others suggest minimal or no correlation. Comparative studies can clarify these discrepancies by providing a more detailed understanding of how pouch size influences postoperative results16.

This research demonstrated that both long and short gastric pouch RYGB techniques are successful in achieving notable weight loss outcomes and remission of obesity-associated medical problems, without significant differences in major complications up to 12 months after the surgery.

Our findings are consistent with existing literature, indicating that RYGB results in substantial weight loss outcomes, regardless of pouch size. A systematic analysis by Mahawar K, et al. revealed that out of 14 studies, nine found no association between the pouch size and weight loss outcomes, while five studies suggested that longer gastric pouches lead to less weight loss26. Additionally, research by Topart P, et al. demonstrated that long gastric pouches are as effective as short gastric pouches in terms of weight loss three years after surgery, with no correlation between TWL% and the size of the gastric pouch. Thus, considering our data alongside previous studies, it appears that the gastric pouch size does not significantly influence weight loss or TWL%, either in the short or long term after the surgery. In 2007, Nishie A, et al. observed that gastric pouch size, measured by a routine upper gastrointestinal study on the first postoperative day, does not influence short-term postoperative weight loss27. In contrast, Ren Y, et al. reported greater weight loss and a higher TWL% in smaller pouches, especially in patients with T2DM and BMI of 30–3515. These findings were supported by Roberts K, et al. indicating smaller gastric pouches might be more efficient in term of weight loss28. Furthermore, in 2020, Mahawar, et al. showed that the width, but not the size, matters in weight loss, meaning that a longer gastric pouch with a small width may improve results29. In our study, the long gastric pouches were created on a narrow (36 Fr) bougie that confirmed the mentioned study by Mahawar, et al.

Our results, suggest that the length of the gastric pouch in RYGB. does not significantly impact the remission of common obesity-associated medical problems during first year after RYGB. These findings, corroborate with a study by Boerboom A, et al., which reported no substantial differences in remission of obesity associated medical problems (T2DM and DLP) at 24 and 36 months of follow-up30. However, they observed differing HTN remission rates between the two groups30. Another study by Gao X, et al. discovered no difference in serum triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and total cholesterol levels between long and short gastric pouch groups16. Yet, they noted better remission of T2DM, evidenced by greater reductions in HbA1c levels, fasting blood glucose, and HOMA-IR in patients with shorter gastric pouches16. An animal study performed by Dolo P. in 2019, represents a distal gastric pouch that significantly impairs glucose tolerance and T2DM remission in a diabetic rat model31. Moreover, Siilin H, et al. noted that gastric pouch size is associated with acid production which indirectly impacts remission of comorbidities32.

Notably, in our series no marginal ulcers or leaks were detected during 12 months post-surgery. Firstly, in 1998, Sepala A, et al. found that the development of marginal ulcers after RYGB is influenced by factors like gastric pouch orientation, staple line integrity, and mucosal ischemia33. Then, Azagury D, et al. identified an increased risk of marginal ulcers in long gastric pouches along with smoking and T2DM34. Moreover, Edholm D, et al. reported a 0.5% incidence of symptomatic marginal ulcer at 6 weeks post-surgery and 0.9% after one year, with a 14% increased risk of marginal ulcer for each additional centimeter in pouch length35. Gao X’s study also found a higher incidence of marginal ulcers in longer pouches (p = 0.023) and identified pouch size as a key predictor for marginal ulceration, though no link was found between gastric pouch size and dumping syndrome or other complications16. These findings are supported by a study from Coblijn U. K, which also indicated reduced GERD symptoms in shorter pouches11. The associations between the role of surgical techniques, particularly the way that gastric pouch is formed, and complication rates are supported by several studies36,37.

The current study indicates that GERD esophagitis was identified through EGD in 15% of patients with long gastric pouches and 12.5% of those with short gastric pouches. However, it is noteworthy that 100% of patients in the long gastric pouch group and 86.4% in the short gastric pouch group reported remission and improvement of pre-existing GERD symptoms. This suggests that a significant majority of patients experienced symptom relief, despite the presence of GERD esophagitis as evidenced by EGD.

We didn’t find any significant difference between two groups in term of weight loss outcomes and remission of obesity associated medical problems at one year after RYGB. Our findings suggest that a long narrow gastric pouch with a volume of approximately 80 cc has no negative impact on weight loss outcomes, remission of comorbidities and complications compared to a short gastric pouch with a volume of around 30 cc at least one year after RYGB. In addition, it has been demonstrated that a large gastric pouch can lead to suboptimal initial clinical response and recurrent weight gain38 that needs at least two years follow-ups to assess them39.

Strengths and limitations

This study’s retrospective nature without randomization and short follow-up period may limit the generalizability of its findings. Additionally, participants’ dietary and physical activity behaviors were not controlled. Moreover, the study primarily focused on the first 12 months, which may not fully capture long-term effects and complications. However, the strengths of this study include a robust sample size and comprehensive data collection. More randomized controlled trials with a longer follow-up period, larger sample size, distinct measurement of gastric pouch volume and controlled behavioral factors is suggested for future studies. Additionally, exploring the physiological and metabolic differences between patients with long and short gastric pouches could provide deeper insights into the effectiveness of these surgical techniques. A more diversified patient demographic could also be beneficial to understanding the impacts across various population groups.

Conclusion

In conclusion, both long and short gastric pouch techniques are effective in achieving considerable weight loss and remission of obesity-associated medical problems without major complications within a 12-month post-surgery period. These findings suggest that the choice between long-narrow and short gastric pouches may be more dependent on individual patient characteristics and surgeon preference rather than a one-size-fits-all approach. Further research is needed to explore the long-term effects and any potential subtle differences that might emerge over time. The absence of significant differences in major complications and the consistency with previous research suggest a broad applicability of these findings in the field of metabolic and bariatric surgery.