Anatomy of the pre-pyloric vein and right gastroepiploic branches: Guiding the transection initiation site for sleeve gastrectomy

Abstract

BACKGROUND

Laparoscopic sleeve gastrectomy (SG) as an effective treatment for obesity and related metabolic diseases which still lacks consensus on gastric transection starting points.

AIM

To investigate reliable anatomical landmarks to enhance surgical precision and improve outcomes.

METHODS

This observational study enrolled 100 patients with obesity who underwent laparoscopic SG between May and October 2024. Intraoperatively, the distance between the prepyloric vein and the first branch of the right gastroepiploic vessels crossing the midline of the pyloric canal (AB distance) was precisely measured to standardize transection initiation site for SG (TIS-SG), with the latter branch defined as the optimal TIS-SG. The study analyzed clinical parameters potentially affecting the AB distance, including sex, and body mass index (BMI). Furthermore, preoperative and postoperative changes in blood glucose and blood pressure were compared to assess the metabolic improvements associated with SG.

RESULTS

The average AB distance was 4.65 ± 0.89 cm, with 4 patients exceeding the recommended maximum of 6 cm. No significant differences were found based on BMI, blood pressure, or fasting glucose levels (P > 0.05). Male patients had a significantly larger AB distance compared to females (4.98 ± 0.99 cm vs 4.53 ± 0.84 cm, P = 0.027). Additionally, fasting blood glucose levels on the third postoperative day showed a significant reduction compared to preoperative levels (P < 0.001).

CONCLUSION

The AB distance is a stable and reliable anatomical marker for defining TIS-SG in SG, independent of metabolic factors and BMI. SG leads to short-term metabolic improvements, including better blood glucose and blood pressure control.

Key Words: Metabolic improvement; Surgical precision; Obesity; Right gastroepiploic artery; Pre-pyloric vein; Transection initiation site; Laparoscopic sleeve gastrectomy

Core Tip: This study identifies the AB distance (between the pre-pyloric vein and right gastroepiploic artery branch) as a stable anatomical marker for defining the transection initiation site for sleeve gastrectomy (SG). Unaffected by metabolic factors or body mass index, it enhances surgical precision. SG also yields short-term metabolic benefits, notably reduced fasting blood glucose.

INTRODUCTION

Obesity has emerged as one of the most significant metabolic diseases globally, posing a major threat to human health. According to the World Health Organization, obesity is defined as a body mass index (BMI) of 30 kg/m² or higher[1]. Over the past 50 years, the global prevalence of obesity has risen substantially, reaching approximately 13%[2]. The latest epidemiological survey data from China (2015-2019) indicate that the prevalence of obesity among adults (≥ 18 years old) is 16.4%[3]. This dramatic rise in obesity rates has contributed to an increase in obesity-related comorbidities, including type 2 diabetes mellitus (T2DM), cardiovascular diseases, and certain cancers, further amplifying the burden on healthcare systems worldwide.

Bariatric surgery has been developed as an effective treatment for obesity for more than 50 years. Among the various surgical procedures, Roux-en-Y gastric bypass and sleeve gastrectomy (SG) are the most widely performed worldwide. In 2018, a total of 696191 bariatric surgeries were performed globally, with SG accounting for 55.4% (386096 cases)[4]. The growing popularity of SG can be attributed to its relatively simple surgical technique and its significant metabolic benefits. Notably, SG has been shown to result in substantial weight loss and improvements in obesity-related conditions. For example, among patients with obesity and T2DM, the remission rate of T2DM 2 years after SG is 61%[5,6], although this rate decreases to 37% after 5 years of follow-up[7]. Furthermore, laparoscopic SG is recognized as a technically feasible and safe procedure, with low complication and mortality rates[8]. Consequently, SG has become the most commonly performed bariatric surgery worldwide, favored for its operational simplicity, short learning curve, and efficacy in achieving sustained weight loss and improving metabolic health.

Despite the widespread use of SG, there remains a lack of consensus regarding the precise surgical technique, particularly concerning the transection initiation site for SG (TIS-SG). Numerous guidelines and consensus statements on SG techniques have been published globally[9,10]. However, specific recommendations regarding the optimal distance from the pylorus to TIS-SG remain debated. The International Consensus on SG suggests that initiating transection at a point 2-6 cm from the pylorus is appropriate[11], and this range has become the standard approach for many surgeons in clinical practice. Prior to dividing the greater omentum, surgeons often measure the distance from the pylorus using various tools, including rulers, sutures, or laparoscopic instruments of known length. However, the absence of standardized, objective anatomical references for this measurement creates variability in practice.

The right gastroepiploic artery and its branches have been identified as prominent anatomical landmarks in the gastric antrum region, often guiding the identification of critical structures during gastric surgery[12]. Despite their usefulness, the precise relationship between these vascular branches and the pylorus remains poorly defined in the literature. Limited documentation exists regarding the exact distance of the right gastroepiploic vessels relative to the pylorus, which could provide a more reliable and reproducible anatomical reference for TIS-SG.

Therefore, our study aims to address this gap by evaluating the position of a specific branch of the right gastroepiploic vessels and determining its consistency as an anatomical landmark for gastric transection in SG. By assessing the distance between this branch and the pylorus, we seek to establish whether it can reliably serve as a reference point for defining TIS-SG, thus improving the precision of the procedure. Identifying a consistent anatomical marker would not only enhance surgical accuracy but also reduce intraoperative variability, ultimately leading to better outcomes for patients undergoing SG.

MATERIALS AND METHODS

Patients

This study is a prospective clinical research project. It will include patients with obesity who underwent SG at the Department of Gastrointestinal Surgery of the China-Japan Friendship Hospital between May 2024 and October 2024. The diagnosis of obesity will be based on the World Health Organization’s recommended standard of a BMI greater than 30 kg/m². The study has been approved by the Ethics Committee of the China-Japan Friendship Hospital (Ethical approval No. 2022-ky-221).

Inclusion criteria: (1) Age ≥ 16 years, regardless of sex; (2) BMI meeting the World Health Organization’s criteria for obesity diagnosis; and (3) Indications for bariatric surgery, with the implementation of standard SG.

Exclusion criteria: (1) A clear diagnosis of type 1 diabetes mellitus; (2) Concurrent malignancies, cardiovascular diseases, or anorexia nervosa; (3) Patients with debilitating diseases, psychiatric disorders, pregnancy, or substance abuse that may affect metabolism; (4) Patients taking oral lipid-lowering medications; and (5) Patients with coexisting thyroid disorders or liver diseases.

The indications for bariatric surgery include[13]: (1) BMI ≥ 40 kg/m² without any obesity-related diseases; (2) BMI ≥ 35 kg/m² with one or more severe obesity-related diseases, such as T2DM, high-risk T2DM states (insulin resistance, prediabetes, and/or metabolic syndrome), poorly controlled hypertension, non-alcoholic fatty liver disease/non-alcoholic steatohepatitis, obstructive sleep apnea, knee or hip osteoarthritis, and stress urinary incontinence; (3) BMI between 30 kg/m² and 34.9 kg/m² in patients with diabetes, where blood sugar control remains inadequate after lifestyle interventions and medication; bariatric surgery should be considered. For Asian patients[14], these BMI thresholds should be lowered by 2.5 kg/m²; and (4) All patients meeting the surgical indications have undergone consultations with the endocrinology department and evaluations for pulmonary function, diet, and psychological assessment. Preoperative examinations include esophagogastroduodenoscopy to assess for hiatal hernia and Helicobacter pylori infection, as well as pulmonary function testing.

Laparoscopic SG

After induction of general anesthesia, the patient is placed in a supine position with legs apart and the head slightly elevated. Pneumoperitoneum is established through Meng’s point using a 0.2 cm horizontal or vertical incision with a Veress needle at the intersection of the lateral border of the left rectus abdominis and rib arch. A trocar is then inserted to maintain intra-abdominal pressure at approximately 14 mmHg (1 mmHg = 0.133 kPa). Additional incisions are made as follows: 1.2-15 cm below the xiphoid along the outer margin of the right rectus muscle, 1.0-18 cm below the xiphoid along the outer margin of the left rectus muscle, and 0.5-3 cm below the xiphoid along the midline rightward. The three-port laparoscopic method is used to complete the operation.

The gastric wall is lifted to locate the pylorus. The pre-pyloric vein (or the pyloric ring if the pre-pyloric vein is unclear) is defined as anatomical landmark A. We have supplemented intraoperative laparoscopic photographs (Supplementary Figure 1) to clearly show the two scenarios where the pre-pyloric vein is visible and where it is not. In practical measurements, we found that the distance between the prepyloric vein and the pyloric ring is extremely close when the vein is clearly identifiable, and there were no significant differences in AB distance measurements between the two scenarios. From point A, the surgeon moves distally to proximally, identifying the first branch of the right gastroepiploic artery along the greater curvature that crosses the pylorus at the horizontal midline, marking it as anatomical landmark B. The distance between points A and B is measured and recorded. Point B is defined as the optimal TIS-SG (Figure 1).

Figure 1 Diagram of anatomical landmarks A and B, and the distance between them. A: The pre-pyloric vein (or the pyloric ring if the pre-pyloric vein is unclear) is defined as anatomical landmark A; B: The first branch of the right gastroepiploic artery along the greater curvature that crosses the pylorus at the horizontal midline is defined as anatomical landmark B; C: Measurement of the distance between points A and B along the greater curvature of the stomach; D: Distance between A and B measured with a ruler intraoperatively.

Subsequently, the right gastroepiploic vessels along the greater curvature are dissected to the gastroesophageal junction. A 36 Fr gastric tube is inserted orally to support the scope of gastric resection and prevent postoperative gastric stricture. A linear cutter is used to transect the stomach wall from point B to approximately 1 cm left of the His angle. The seromuscular layer is then sutured to reinforce the gastric resection margin. The volume of the remaining stomach is approximately 100 mL.

Research endpoints

The primary endpoint of this study is the AB distance (between the pre-pyloric vein and the first branch of the right gastroepiploic artery crossing the pylorus midline), which serves as the anatomical basis for defining TIS-SG. Secondary endpoints include demographic data (age, BMI, waist circumference), surgical-related indicators directly associated with TIS-SG (surgical time, intraoperative blood loss), and metabolic-related indicators before and after surgery (blood glucose and blood pressure).

Other parameters

Postoperative monitoring will be conducted on the first, second, and third mornings after surgery, including blood pressure measurements and fasting blood glucose testing. The corresponding results will be recorded. Postoperative complications and their management will also be documented. Total hospital stays and total expenses will be recorded.

Statistical analysis

Statistical analysis will be performed using SPSS 25.0 software. The Shapiro-Wilk test will be used to assess data normality. Data following a normal distribution will be expressed as mean ± SD, with inter-group differences analyzed using independent sample t-tests, paired sample t-tests, and ANOVA. Data not following a normal distribution will be expressed as median (interquartile range), with inter-group differences analyzed using independent sample rank sum tests. Categorical data will be presented as n (%). All tests are two-sided, and a P value < 0.05 will be considered statistically significant.

RESULTS

Characteristics of enrolled patients

Between May 2024 and October 2024, a total of 100 patients with obesity met the inclusion criteria and underwent laparoscopic SG at our hospital. Among them, 27 were male (27%) and 73 were female (73%). The mean age was 32.94 ± 7.99 years, mean height was 168.63 ± 7.17 cm, mean weight was 117.14 ± 28.28 kg, mean BMI was 41.05 ± 8.64 kg/m², mean waist circumference was 120.90 ± 19.77 cm, mean fasting blood glucose was 6.48 ± 2.11 mmol/L, mean baseline systolic blood pressure (SBP) was 140.94 ± 20.73 mmHg, and mean baseline diastolic blood pressure (DBP) was 91.08 ± 15.56 mmHg.

Among male patients, height, weight, BMI, and waist circumference were significantly higher than in female patients (P ≤ 0.05). Additionally, male patients had significantly higher baseline SBP compared to female patients (P ≤ 0.05) (Table 1).

Table 1 Clinical parameters of 100 patients with obesity who underwent sleeve gastrectomy.

Parameter	Male (n = 27)	Female (n = 73)	P value
Age (year)	33.89 ± 9.10	32.59 ± 7.58	0.473
Height (cm)	176.26 ± 5.57	165.80 ± 5.43	0.000
Weight (kg)	139.14 ± 30.55	109.01 ± 22.67	0.000
BMI (kg/m2)	44.75 ± 9.49	39.69 ± 7.94	0.009
Waist circumference (cm)	136.82 ± 22.90	114.97 ± 14.70	0.000
Fasting blood glucose (mmol/L)	6.54 ± 2.12	6.45 ± 2.12	0.846
Systolic blood pressure (mmHg)	148.19 ± 24.66	138.26 ± 18.56	0.033
Diastolic blood pressure (mmHg)	96.07 ± 18.26	89.23 ± 14.14	0.051

BMI: Body mass index.

Surgical and hospitalization details

All patients successfully completed the surgical procedure, with no conversions to open surgery. The mean surgical time was 1.87 ± 0.32 hours, mean intraoperative blood loss was 9.54 ± 9.30 mL, and mean length of the gastric resection margin was 22.84 ± 2.97 cm. No severe complications occurred, and postoperative recovery was uneventful.

On the first postoperative day, all enrolled patients completed blood pressure monitoring and fasting blood glucose testing. On the second postoperative day, 98 patients completed blood pressure monitoring (2 patients refused), and 94 patients completed fasting blood glucose testing (6 patients refused). On the third postoperative day, 21 patients did not complete blood pressure or blood glucose monitoring due to discharge on the second day.

The mean length of hospital stay was 8.28 ± 3.07 days, and the mean hospitalization cost was 60601.28 ± 11349.28 RMB.

Localization of TIS-SG

The mean distance between the pyloric vein and the first branch of the right gastroepiploic artery crossing the pyloric canal midline (AB distance) was 4.65 ± 0.89 cm (Figure 2). No AB distance was less than 2 cm in any enrolled patients. However, 4 patients had an AB distance exceeding the recommended upper limit of 6 cm according to guidelines. The “2-6 cm” range in international guidelines is a general recommendation rather than an absolute contraindication. In actual surgical practice, we prioritize inherent vascular anatomical landmarks over arbitrary numerical thresholds, so we strictly selected point B as the transection initiation site for these 4 cases without adjusting to 6 cm. Postoperatively, all 4 patients had a stable recovery with no adverse events such as gastric stasis or reflux, and the degree of fasting blood glucose reduction was consistent with the overall cohort. The AB distance in male patients was 4.98 ± 0.99 cm, significantly greater than that in female patients (4.53 ± 0.84 cm, P = 0.027).

Figure 2  Scatter plot of AB distance.

When patients were grouped according to BMI, no significant differences in AB distance were observed among the four groups: Mild obesity, moderate obesity, severe obesity, and morbid obesity (P = 0.183). Patients with SBP ≥ 140 mmHg or DBP ≥ 90 mmHg were assigned to the high blood pressure group, while those with SBP < 140 mmHg and DBP < 90 mmHg were assigned to the normal blood pressure group. No significant difference in AB distance was observed between these groups (4.79 ± 0.96 vs 4.54 ± 0.85, P = 0.167). Based on preoperative fasting blood glucose levels, patients were divided into a normal blood glucose group (< 6.1 mmol/L) and an elevated blood glucose group (≥ 6.1 mmol/L). Again, no significant difference in AB distance was observed between these groups (4.68 ± 0.94 vs 4.61 ± 0.86, P = 0.686). These results are presented in Figure 3.

Figure 3 AB distance in different grouping states. ^aP < 0.05. NS: No significant; BMI: Body mass index; BP: Blood pressure.

Changes in blood pressure and blood glucose levels

On the first postoperative day, both systolic and DBP values were lower than preoperative levels, but the differences were not statistically significant (P = 0.311 and P = 0.568, respectively). The fasting blood glucose measured on the morning of the first postoperative day was 6.54 ± 1.18 mmol/L, significantly higher than the preoperative level (P < 0.001).

On the second postoperative day, DBP was significantly lower than preoperative values (83.31 ± 12.29 mmHg vs 91.08 ± 15.56 mmHg, P < 0.001), whereas SBP showed no significant difference. Fasting blood glucose on the second postoperative day remained significantly higher than preoperative levels (P < 0.001).

By the third postoperative day, both systolic and DBP values showed no significant differences compared to preoperative levels. However, fasting blood glucose was significantly lower than the preoperative level (6.01 ± 1.12 mmol/L vs 6.48 ± 2.11 mmol/L, P < 0.001) (Table 2).

Table 2 The changes of blood pressure and fasting blood glucose.

Parameter	Systolic blood pressure	Diastolic blood pressure	Fasting blood glucose
Pre-operation	140.94 ± 20.73	91.08 ± 15.56	6.48 ± 2.11
1st postoperative day	134.00 ± 14.85	84.94 ± 11.34	6.54 ± 1.18
P value	0.311	0.568	< 0.001
2nd postoperative day	132.35 ± 14.62	83.31 ± 12.29	6.56 ± 1.24
P value	0.105	< 0.001	< 0.001
3rd postoperative day	130.14 ± 13.19	80.33 ± 11.07	6.01 ± 1.12
P value	0.071	0.107	< 0.001

DISCUSSION

Our study is the first to systematically evaluate the AB distance to define the TIS-SG and assess its clinical utility in SG. The results revealed that the mean AB distance was 4.65 ± 0.89 cm, with high consistency observed across BMI categories and preoperative metabolic parameter subgroups. This consistency highlights the relative stability of this anatomical landmark, supporting its use as a reliable reference point for TIS-SG during SG. This landmark represents a safe and effective surgical method. Once its effectiveness and rationality are established, there is no need to use a tape measure or grasping forceps to determine the starting transection position. Instead, the first branch of the right gastroepiploic vessels that crosses the pyloric canal horizontal midline (point B) can be directly used as the starting point for stomach transection, which also improves surgical efficiency. Currently, we have not encountered any patients in whom point B is invisible, further demonstrating the stability of this anatomical landmark. These findings provide a robust scientific foundation for selecting the gastric transection starting point, contributing to improved precision and standardization in SG procedures.

The right gastroepiploic artery originates from the gastroduodenal artery and travels along the greater curvature of the stomach from right to left between the two layers of the anterior leaf of the greater omentum. Along its course, it gives off branches to the anterior and posterior walls of the stomach and the greater omentum. At its origin, it emits pyloric branches supplying the pylorus, and it also sends gastric branches upward to supply the anterior and posterior surfaces of the right half of the greater curvature. The right gastroepiploic vein runs alongside the artery[15]. Although the right gastroepiploic vessels and their branches are prominently visible during SG, their potential clinical significance has largely been underappreciated. Our study identified that the measured AB distance falls within the recommended range of 2-6 cm from the pylorus, as outlined by the International Expert Consensus on SG, which holds significant clinical value. Traditionally, the starting point for gastric transection during SG has relied heavily on the subjective judgment of surgeons or imprecise measurement tools. The precise identification of the AB distance, and thus TIS-SG, minimizes measurement errors and subjective bias, enhancing the accuracy and safety of SG through standardized TIS-SG localization. Moreover, the consistency of this landmark across diverse patient populations facilitates intraoperative localization, thereby reducing operative time and easing the learning curve for surgeons.

Furthermore, our study revealed that gender has a subtle impact on the AB distance, with male patients exhibiting a significantly greater AB distance (4.98 ± 0.99 cm) compared to female patients (4.53 ± 0.84 cm). We previously analyzed the relationship between height and AB distance by dividing the entire study population into two groups based on the median height, and found that AB distance is not independently correlated with height (P = 0.31). Since BMI inherently incorporates height as a factor, we avoided redundant presentation of this result to prevent repetition. This difference may be attributed to variations in anatomical characteristics, fat distribution, and intra-abdominal space. Consistently, male patients with obesity had significantly greater height (P ≤ 0.05), weight (P ≤ 0.05), and BMI (P ≤ 0.05) than female patients, aligning with previous research on anatomical differences in obese populations[16]. Nevertheless, the AB distances for both male and female patients fall within the guideline-recommended range of 2-6 cm, suggesting that the impact on clinical practice may be limited. However, this finding highlights the importance of individualized TIS-SG localization to ensure surgical precision.

Our study also revealed that differences in preoperative blood pressure, blood glucose levels, or BMI classifications did not significantly influence the AB distance (P > 0.05). This has several important implications. First, the consistency of the AB distance across individuals with varying metabolic states, such as hypertension or hyperglycemia, underscores its reliability as an anatomical landmark. This stability is particularly crucial in clinical practice, given the complex and dynamic metabolic conditions often present in patients with obesity, especially those with metabolic syndrome[17,18]. Second, BMI, as an important indicator of obesity classification, reflects body fat levels and their potential impact on internal organ positioning[19,20]. Our study demonstrates that, regardless of whether patients are mildly obese or morbidly obese, the AB distance remains relatively consistent. This indicates that the AB distance primarily depends on stable anatomical characteristics rather than body fat distribution or degree of obesity. This broad applicability across different obesity classifications further enhances its value as a standard anatomical reference point in surgical procedures.

In addition, anatomical point B may help reduce surgical risks in patients with a history of abdominal surgeries or intra-abdominal adhesions. For example, patients who have previously undergone laparoscopic cholecystectomy may have adhesions between the gallbladder bed and the pyloric canal, making it difficult to accurately determine the starting point for gastric transection[21]. In such cases, adhesiolysis or dissection may be required, potentially causing tissue damage or bleeding. The exposure of anatomical point B is relatively straightforward, allowing for faster and more accurate determination of the starting point for gastric transection, thereby reducing surgical risks and shortening overall surgery time.

The finding that metabolic characteristics have minimal impact on the AB distance indirectly highlights the independence of this anatomical landmark. Compared to some surgical reference points that are easily influenced by individual metabolism, inflammation, or organ displacement[22], the consistency of the AB distance reduces the complexity of intraoperative localization, minimizes operation errors owing to individual variability, and improves surgical precision. However, the size of the stomach varies among individuals. If the transection starts at a fixed distance from the pylorus, these differences may be magnified. Using this anatomical landmark for TIS-SG helps avoid such effects and is more suitable for individualized SG. In conclusion, these results not only validate the reliability of the AB distance but also lay the foundation for its further application in SG. Future studies with larger and more diverse populations can further clarify the universality and standardization value of the AB distance in broader clinical practice.

Although the primary endpoint of this study was anatomical evaluation, changes in metabolic indicators during the early postoperative period also revealed important clinical significance. The significant increase in fasting blood glucose levels on the first and second postoperative days may be closely related to the postoperative stress response[23]. Surgery is a major physiological stressor that triggers the release of stress hormones such as cortisol and adrenaline, stimulating glycogenolysis and gluconeogenesis, leading to short-term elevations in blood glucose[24]. Furthermore, postoperative fasting or dietary restrictions may reduce exogenous glucose intake, causing the body to rely more on endogenous glucose release, further contributing to blood glucose fluctuations. By the third postoperative day, fasting blood glucose levels significantly improved, falling below preoperative levels, indicating that the glucose-regulating effect of SG had begun to manifest[25-27].

It is also noteworthy that DBP significantly decreased on the second postoperative day, suggesting a potential positive effect of SG on blood pressure control. This may be related to adjustments in fluid balance and improvements in vascular function. Reduced dietary intake and changes in intraoperative fluid management can lead to temporary fluctuations in blood volume, affecting blood pressure levels. Additionally, initial weight loss and improved metabolic status, such as reduced insulin resistance, may lower peripheral vascular resistance, further promoting decreases in blood pressure[28,29].

These results are consistent with previous studies and provide additional evidence for the role of SG in managing obesity and metabolic-related diseases[30]. Prior research has shown that SG not only induces weight loss but also effectively alleviates obesity-related metabolic disorders, including improvements in blood glucose and blood pressure[31]. The early findings of this study supplement this evidence, demonstrating a rapid onset of metabolic improvement postoperatively. Future studies could extend the follow-up period to examine whether these metabolic improvements are sustained long-term and assess their impact on cardiovascular risk and quality of life. Overall, these findings reinforce SG as an essential tool in the comprehensive management of obesity and its associated metabolic conditions.

This study also has several limitations. First, the sample size is relatively small, and it is being conducted at a single center, which may limit the generalizability of the results. Second, the short postoperative follow-up period prevented a comprehensive assessment of the long-term impact of AB distance selection on metabolic improvements and weight loss. Third, this study is single-arm, with no control group. Fourth, we did not measure the distance from the pylorus to the xiphoid process during the study period, which may limit the in-depth analysis of the anatomical nature of the AB distance; this indicator can be included in subsequent measurements. Fifth, none of the enrolled patients had a history of upper abdominal surgery, so the applicability of the proposed anatomical marker in patients with such a history requires further research to confirm. Future multi-center, large-scale studies with long-term follow-up will be needed to further validate these findings.

CONCLUSION

By assessing the anatomical relationship between the anterior pyloric vein and the first branch of the right gastric omental vessels that crosses the pyloric canal horizontal midline (AB distance), this study validates the clinical value of anatomical point B as the TIS-SG. The findings demonstrate that point B possesses good stability and reliability, providing strong support for selecting the cutting initiation point during surgery. Additionally, the study reveals early postoperative metabolic improvements following SG, highlighting its role in the management of obesity and associated metabolic conditions.