Analysis of Early Dilation of the Residual gastric After Laparoscopic Sleeve Gastrectomy: Insights from a 3D CT Reconstruction Study

doi:10.21203/rs.3.rs-5009520/v1

Background Laparoscopic sleeve gastrectomy (LSG) is currently the most commonly performed bariatric surgery due to its effective weight loss and low complication rates. However, some patients experience weight regain or insufficient weight loss due to residual gastric dilation, the factors of which are unclear. This study uses 3D CT reconstruction to measure changes in residual gastric volume after LSG and investigates factors contributing to gastric dilation and its impact on weight loss.

Method This retrospective study involved 50 LSG patients. Preoperative clinical and laboratory data were collected. Residual gastric volume was measured using 3D CT reconstruction at 1 and 3 months post-surgery. The study assessed total sleeve volume (TSV), tube volume (TV), and antral volume (AV). Resected gastric volume and staple line length were measured during surgery. Weight metrics and laboratory indices were recorded at 1, 3, 6, and 12 months post-surgery. The Three-Factor Eating Questionnaire-R21 (TFEQ-R21), the Eating Behavior and Belief Scale Questionnaire (EBBS-Q), and the Gastroesophageal Reflux Disease Questionnaire (GERD-Q) were used to assess patients' postoperative dietary behavior, treatment adherence, and reflux condition, respectively. Correlations between weight metrics, residual gastric dilation, and the aforementioned factors were analyzed.

Results The 50 patients had a mean preoperative BMI of 42.27 ± 7.19 kg/m² and an average total weight loss (%TWL) of 34 ± 7% one year post-LSG. One month post-LSG, mean TV, AV, and TSV were 45.93 ± 16.75 mL, 115.85 ± 44.92 mL, and 161.77 ± 55.37 mL, respectively. %TWL at one year significantly correlated with residual gastric dilation (p < 0.05). Three months post-surgery, the degree of residual gastric dilation was 13.50 ± 17.35%. Initial residual gastric volume, preoperative diabetes, and postoperative reflux were associated with dilation.

Conclusion Residual gastric dilation post-LSG significantly affects weight loss efficacy. Factors including initial residual residual gastric volume, preoperative diabetes, and postoperative reflux are associated with residual gastric dilation.

Laparoscopic sleeve gastrectomy

residual gastric dilation

CT 3D reconstruction

● Residual gastric dilation post-LSG significantly affects weight loss efficacy.

● Residual gastric volume, preoperative diabetes, and postoperative reflux are associated with dilation.

● Residual gastric volume was not related to weight loss.

Obesity is defined as an excess of body fat, which can cause various diseases, such as dyslipidemia, hypertension, diabetes, coronary heart disease, and non-alcoholic fatty liver disease¹, ². Bariatric surgery is the only effective and currently available therapy for sever obesity³. Laparoscopic sleeve gastrectomy (LSG) is the most frequently used bariatric procedure worldwide due to the effective weight loss, simple procedure, and few complications⁴, ⁵. LSG involves the excision of approximately 80% of the stomach, mainly the body and fundus, creating a tubular duct along the lesser curvature, which results in restricted food intake and subsequent weight loss⁶ (Fig. 1). However, compared to malabsorptive procedures, LSG tends to have higher rates of insufficient weight loss and weight regain⁷.

Long-term studies report an appreciable frequency of inadequate weight loss or even weight regain after LSG, with an estimated failure rate of 14–37%⁸. Residual gastric dilatation was held responsible for inadequate weight loss or weight regain following LSG, as candidates for revisional surgery after LSG usually exhibit large gastric volumes⁹, ¹⁰. Several studies have indicated that the dilation of the residual gastric is one of the possible reasons for weight regain and inadequate weight loss¹¹, ¹². However, the factors contributing to residual gastric dilation after LSG have not been clarified, prompting further investigation. Patients’ eating habits, gastric compliance, residual gastric morphology, and surgical technique are all factors that may contribute to gastric dilation, but they remain controversial¹³, ¹⁴. In this study, we measured the gastric volume by 3D CT reconstruction at 1 and 3 months following LSG to evaluate the association between gastric dilation and weight loss. We also analyzed the possible contributing factors to gastric dilation, including preoperative clinical baseline data, gastric morphology indicators, treatment adherence, eating behaviors, and other follow-up indicators. By identifying the contributing factors to gastric dilation and weight loss effect after LSG, we can enhance postoperative management strategies, help to mitigate the risk of weight regain, and ensure sustained weight loss.

This retrospective study included 50 patients who underwent LSG for the treatment of sever obesity at The Affiliated Hospital of Qingdao University between January 1, 2018, to January 1, 2022. The study was conducted in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice. Informed consent was obtained from all individual participants included in the study. Ethical approval for the study was obtained from the Institutional Review Board (IRB) of The Affiliated Hospital of Qingdao University (Approval Number: QYFY WZLL 28969). The study included patients aged 18 to 60 years old, with a body mass index (BMI) ≥ 32.5 kg/m² or a BMI between 27.5–32.5 kg/m² associated with comorbidity, who had not responded to conservative treatment. Patients with severe gastroesophageal reflux disease, uncontrolled psychological or eating disorders, drug or alcohol abuse, high surgical risk, uncontrolled endocrine disorders, noncompliance with medical treatment, or severe liver disease were excluded from the study.

All patients underwent thorough history taking and clinical examination before LSG. Preoperative baseline data collected included age, gender, BMI, coexisting diseases, and history of smoking and alcohol consumption. Preoperative laboratory investigations comprised routine blood tests, blood glucose measurements (HbA1c, fasting blood glucose, C-peptide, and insulin), blood lipid profiles, liver and kidney function tests, and other relevant indicators. Additionally, clinical examinations included an ECG, upper gastrointestinal endoscopy, chest-abdominal CT, and pulmonary function tests to assess the patients' general condition, cardiopulmonary function, and any coexisting diseases.

Surgical Technique

Two surgeons performed all LSG procedures. A standardized three or four port technique was used for all patients in the study. All procedures were conducted under general anesthesia, with patients placed in the supine position. After mobilizing the fundus and exposing the angle of His, a Bougie (36 Fr) was inserted to guide gastric resection, which was performed using five to seven 60-mm staples. The first firing of the stapler began 4 cm from the pylorus, and the final firing was completed about 1 cm lateral to the angle of His. The choice of cartridge was based on gastric wall thickness and compressibility, utilizing a green load for the initial firing and blue loads for subsequent applications. Seromuscular reinforcement was done along the staple line, resulting in a small gastric sleeve with a capacity of 80–120 ml. The resected stomach was retrieved through a 12-mm port site, after which an abdominal drain was placed along the length of the gastric staple line.

3D CT Gastric Volumetry

All imaging examinations were performed by experienced radiologists at the Department of Radiology of our university hospital using a multidetector CT scanner (GE Optima CT670, GE Healthcare). Gastric volumetry was assessed 1 and 3 months after surgery. Fasting and water deprivation for 4 hours before the CT examination. The patients were instructed to quickly drink as much of water as possible until the patient felt full to ensure sufficient gastric filling. Image acquisition was performed in the supine position. The resulting distension was standardized using the same preparation and technique in each case. Thin section images were reconstructed in 5mm slice thickness increments with 0.625 mm detector collimation. Data were transferred to a dedicated 3D workstation. 3D volume-rendering images were created by a combination of manual and semi-automatic segmentation tools. Using height, width, and depth parameters from the cardia to the pylorus, the gastric volume was calculated after multiplane reconstruction and 3D volume rendering (Fig. 2). All gastric CT data were analyzed by the same radiologist, who was blinded to the body weight and %TWL of the patients. The following parameters of the residual gastric were assessed: the total sleeve volume (TSV), the tube volume (TV) (corresponding to the volume of the stomach from the beginning to the end of the staple line), and the antral volume (AV) (corresponding to the volume between the end of the staple line and the pylorus, and the diameter of the gastric tube at midway). The degree of residual gastric dilation was computed using the following formula: Degree of Residual Gastric Dilation = [(Total Stomach Volume at 3 months - Total Stomach Volume at 1 month) / Total Stomach Volume at 1 month] × 100.

Measurement of Resected Gastric Volume

The measurement of the resected gastric volume was standardized. A 16-Fr Foley catheter was inserted into an incision made in the fundus, which was then secured with a purse-string suture to tightly close the opening and fix the catheter in place. Saline was manually injected using a 50-mL syringe until leakage was observed from the staple line. The volume of water injected into the stomach is equal to the resected gastric volume.

Postoperative Follow-up Data

According to our protocol, postoperative analgesic, anti-infection and anticoagulant treatment was routinely administered. Patients were encouraged to get out of bed and were given a clear liquid diet in the early postoperative period. The abdominal drainage tubes could be removed if there were no abnormalities in the upper gastrointestinal radiography on the third day after operation and the patient was discharged a day later. Each participant will meet with our dietitian and be provided with postoperative dietary guidance. All patients underwent follow-up evaluations in the outpatient clinic at 1-, 3-, 6-, 12-month after surgery and every year after surgery. The weight loss-related data collected included body mass index (BMI) and percentage of total weight loss (%TWL). The other follow-up contents included comorbidity remission, laboratory examinations, imaging examinations, and follow-up questionnaires. The postoperative follow-up questionnaires includes The Three-Factor Eating Questionnaire (TFEQ-R21), The Eating Behavior after Bariatric Surgery (EBBS) Questionnaire, and Gastroesophageal Reflux Disease Questionnaire (GRED-Q). These tools are utilized to evaluate patients' postoperative dietary behaviors, adherence to treatment protocols, and the presence of reflux conditions. The TFEQ-R21 assessed three dimensions of eating behavior during the psychological evaluation after bariatric surgery: cognitive restraint, disinhibition, and hunger¹⁵. The three factors of the TFEQ-R21 have demonstrated adequate internal consistency and validity in populations with obesity. The EBBS Questionnaire, a self-administered survey consisting of 11 items, addressed aspects of food, beverages, behavior, and lifestyle¹⁶. It quantified patients' adherence to dietary and lifestyle recommendations following bariatric surgery by assessing compliance with postoperative guidelines. The GERD-Q is a simple, self-administered tool used to evaluate GERD symptoms¹⁷. It includes six items that ask patients to report the number of days they experienced symptoms and their use of over-the-counter (OTC) medications during the previous seven days. All questionnaires were completed during outpatient visits or telephone follow-ups.

Outcome of the Study

The objectives of this study were twofold: (1) to investigate the influence of residual gastric dilation on the efficacy of weight loss, and (2) to analyze the factors related to residual gastric dilation from a multifactorial perspective, including clinical characteristics, surgical procedures, radiological images and psychological factors.

Data and Statistical Analysis

Data analysis was conducted using SPSS version 26.0. All continuous variables were tested for normality. The arithmetic mean and standard deviation were calculated. To compare means between two groups, Student’s t-test was employed, while analysis of variance (ANOVA) was used for comparisons involving more than two groups. The Pearson correlation coefficient (r) was utilized to assess the association between two variables. A significance level of 0.05 was adopted for all statistical tests.

The Study Population and Baseline Characteristics

From January 1, 2018, to January 1, 2022, a total of 83 patients underwent LSG. Of these, 50 patients completed the follow-up protocol for the study. Baseline characteristics of the study population are presented in Table 1. Among the 50 included patients, 66% were female, with a mean age of 32.65 ± 8.31 years, and a mean BMI of 42.27 ± 7.19 kg/m².

Table 1

Demographic characteristics in 50 subjects before laparoscopic sleeve gastrectomy (n = 50)
Characteristic	before SG
Age (years)	32.65 ± 8.31
Gender (Male/Female)	16/34
Height (cm)	169.82 ± 7.89
Body weight (kg)	121.49 ± 25.15
Body Mass Index (kg/m2)	42.27 ± 7.19
Comorbidities
Type 2 diabetes	18(36%)
Hypertension	13 (26%)
Hyperlipidemia	7(14%)
Hyperuricemia	19(38%)
Gastroesophageal reflux disease (GERD)	18(36%)
Obstructive sleep apnea (OSA)	22(44%)
Joint diseases	8(16%)
Non-alcoholic fatty liver disease (NAFLD)	21(42%)
Smoking	10(20%)
Alcohol Consumption	8(16%)

Weight Loss

Table 2 presents a significant decrease in weight and BMI throughout the 12-month follow-up period, with a gradual increase in %TWL at each follow-up time point (p < 0.05 for all comparisons). The line graphs showing the trend of weight changes are also presented in (Figure 3).


	Weight (kg)	Body Mass Index (kg/m2 )	Total Body Weight Loss (%)
Preoperative	121.49 ± 25.15	42.27 ± 7.19
1 Months	106.19 ± 21.99	36.85 ± 6.25	12 ± 3
3 Months	93.91± 19.61	32.59 ± 5.47	23 ± 4
6 Months	86.52 ± 18.11	30.02 ± 5.02	29 ± 5
12 Months	79.81 ± 14.84	27.75 ± 4.13	34 ± 7

Table 2 Change of Weight and Body Mass Index Throughout the Follow-Up Period (n = 50)

Residual Gastric Volumetry in the Whole Studied Population (n = 50)

The volume of the whole residual gastric and its components (body and antrum) at 1 and 3 months after surgery is shown in Table 3. One months after LSG, mean gastric volumes and dimensions assessed by 3D CT reconstruction were as follows: 161.77 ± 55.37 mL for the total gastric volume, 115.85 ± 44.92 mL for the tube volume, and 45.93 ± 16.75 mL for the antrum volume. Three months after surgery, we found that mean gastric volume in the whole studied population (total sleeve volume and gastric tube volume) was significantly increased (p < 0.001). The volume of the antrum was also increased at 3 months but to a smaller extent (p = 0.038). The mean volume of the resected stomach is 793.08 ± 156.03 mL, and the length of the stapling line of the stomach removed during the operation was measured to be 33.75 ± 3.92 cm (Fig. 4).

Figure 4 Volume Measurement of the Resected Stomach After Water Injection.

Table 3

Measurement of AV, TV, and TSV 1 month and 3 months after LSG and the degree of residual gastric expansion at 3 months post-surgery.
Residual Gastric measurement	1 month	3 month	P value
Antral volume (AV), mL	45.93 ± 16.75	48.14 ± 16.40	0.038
Tube volume (TV), mL	115.85 ± 44.92	126.29 ± 38.27	< 0.001
Total sleeve volume (TSV), mL	161.77 ± 55.37	174.43 ± 47.30	< 0.001
Degree of Residual Gastric Dilation, %	——	13.50 ± 17.35

Table 3 Measurement of AV, TV, and TSV 1 month and 3 months after LSG and the degree of residual gastric expansion at 3 months post-surgery.

Evolution over Time of the Clinical and Blood Biochemical Parameters

Table 4 demonstrates the longitudinal changes in biochemical parameters, and complete blood cell counts from preoperative to postoperative follow-up (POM1, PIM3, POM6 and POM12). The results indicate improved glycemic control where patients’ HbA1c, fasting insulin and fasting C-peptide were significantly reduced 1, 3, 6, and 12 months after LSG compared to the baseline (p<0.05). In addition, patients had higher HDL and total cholesterol, and lower triglyceride and LDL at 12 months after LSG. The serum levels of ALT and AST showed a significant reduction compared to baseline, indicating improved liver function. It is worth noting that the level of uric acid significantly increased in the first month after surgery, and gradually decreased after three months. Inflammatory markers CRP decreased significantly 1 year after surgery. The other biochemical parameters demonstrated no differences after LSG.


Laboratory parameter	Time of observation					P value
Laboratory parameter	Pre-op	POM 1	POM 3	POM 6	POM 12	P value
Albumin, g/L	42.41 ± 3.47	39.53 ± 3.18	38.74 ± 3.16	40.15 ± 4.22	44.23 ± 3.51	0.134
ALT, U/L	38.97 ± 49.69	45.39 ± 37.75	39.28 ± 32.96	45.39 ± 37.75	45.39 ± 37.75	< 0.001
AST, U/L	25.67 ± 19.16	28.39 ± 22.34	26.13 ± 20.12	22.12 ± 17.58	20.53 ± 12.64	< 0.001
Total Bilirubin, umol/L	10.61 ± 6.17	15.32 ± 7.25	13.22 ± 6.45	12.79 ± 5.21	11.23 ± 4.93	0.276
Uric Acid, umol/L	402.04 ± 156.22	452.65 ± 188.22	412.55 ± 103.22	342.63 ± 124.22	325.88 ± 88.93	< 0.001
Triglycerides, mmol/L	1.56 ± 0.82	1.16 ± 0.34	1.18 ± 0.62	1.07 ± 0.51	0.93 ± 0.87	< 0.001
HDL, mmol/L	1.24 ± 0.25	1.04 ± 0.19	1.21 ± 0.26	1.36 ± 0.33	1.44 ± 0.28	< 0.001
LDL, mmol/L	3.07 ± 0.84	2.57 ± 0.71	2.83 ± 0.82	3.04 ± 0.95	2.95 ± 0.87	< 0.001
Total Cholesterol, mmol/L	4.80 ± 1.14	4.32 ± 0.92	4.41 ± 1.23	4.55 ± 1.32	4.93 ± 1.05	< 0.001
WBC, 10⁹/L	8.25 ± 1.92	5.79 ± 1.58	6.18 ± 1.92	6.90 ± 2.14	6.25 ± 1.81	0.235
CRP, mg/L	10.22 ± 7.71	4.37 ± 5.06	5.62 ± 4.37	3.38 ± 5.14	4.68 ± 3.41	< 0.001
Fasting Blood Glucose, mmol/L	5.45 ± 1.34	5.32 ± 1.06	5.01 ± 0.79	4.55 ± 2.11	4.93 ± 0.61	0.125
Insulin, µIU/mL	30.31 ± 3.41	21.33 ± 2.06	12.54 ± 1.43	11.58 ± 1.95	10.27 ± 1.21	< 0.001
C-Peptide, ng/L	4.30 ± 1.77	4.08 ± 1.23	2.95 ± 0.98	2.34 ± 1.03	1.98 ± 0.92	< 0.001
HbA1c, %	6.00 ± 1.02	5.72 ± 0.75	5.23 ± 0.52	5.09 ± 0.43	4.92 ± 0.51	< 0.001

Table 4 Comparison of preoperative and postoperative (POM1, POM3, POM6 and POM12) changes in clinical parameters.

Correlation between Clinical Data, Follow-up Questionnaires, Residual Gastric Volume and 1-year% TWL

The results of the analysis indicate that there is no correlation between the residual gastric volume at 1 or 3 months post-surgery and the %TWL 1 year after surgery. Furthermore, no significant correlation was observed between the resected gastric volume and the 1-year %TWL. It was positively correlated with BMI (r = 0.509, p < 0.001) ,CR score (r = 0.348, p = 0.032) and the EBBS questionnaire (r = 0.662, p < 0.001) (Table 5).

Analysis of Factors Related to Residual Gastric Expansion

We conducted a further analysis of the factors associated with residual gastric expansion. Our findings indicate that residual gastric volume (r = -0.511, p < 0.001) are negatively correlated with the expansion of gastric volumes. Conversely, GERD-Q scores are positively correlated with gastric volume expansion (r = 0.450 p = 0.001). Additionally, the correlation analysis between clinical characteristics and gastric volume expansion revealed that patients with type 2 diabetes preoperative are more likely to experience dilation of the residual gastric (Table 5).

Table 5

Correlation between 1-year %TWL and degree of residual gastric dilation with baseline data and follow-up information.
	Value	1-year %TWL		Degree of Residual Gastric Dilation
		r	P value	r	P value
Age, years	32.65 ± 8.31	0.126	0.382	−0.260	0.068
Gender, Male/Female	16/34	0.171	0.236	−0.072	0.617
Body Mass Index, kg/m2	42.27 ± 7.19	0.509	< 0.001	−0.249	0.082
Type 2 diabetes, %	18(36%)	−0.187	0.192	0.286	0.044
Smoking, %	10(20%)	−0.107	0.459	−0.061	0.673
Alcohol Consumption, %	8(16%)	−0.048	0.740	−0.114	0.429
Preoperative Fasting Blood Glucose, mmol/L	5.45 ± 1.34	0.206	0.152	0.043	0.764
Preoperative Insulin, µIU/mL	30.31 ± 3.41	−0.108	0.456	0.032	0.827
Preoperative C-Peptide, ng/L	4.30 ± 1.77	0.036	0.804	−0.054	0.708
Preoperative HbA1c, %	6.00 ± 1.02	0.213	0.138	−0.125	0.385
WBC, 10⁹/L	8.25 ± 1.92	0.074	0.609	0.074	0.607
CRP, mg/L	10.22 ± 7.71	0.197	0.170	0.091	0.532
1 month remnant stomach measurement
Antral volume (AV), mL	45.93 ± 16.75	0.100	0.489	−0.417	0.003
Tube volume (TV), mL	115.85 ± 44.92	0.146	0.313	−0.474	0.001
Total sleeve volume (TSV), mL	161.77 ± 55.37	0.148	0.304	−0.511	< 0.001
3 month remnant stomach measurement
Antral volume (AV), mL	48.14 ± 16.40	0.098	0.497	−0.255	0.074
Tube volume (TV), mL	126.29 ± 38.27	0.076	0.599	−0.208	0.147
Total sleeve volume (TSV), mL	174.43 ± 47.30	0.096	0.508	−0.257	0.072
Degree of Residual Gastric Dilation, %	13.50 ± 17.35	−0.362	0.010	——	——
Resected stomach measurements
Resected stomach volume, mL	793.08± 156.03	0.072	0.621	−0.195	0.174
Spinal length, cm	33.75± 3.92	−0.075	0.604	−0.197	0.169
Three-Factor Eating Questionnaire-R21
CR	19.82± 3.85	0.348	0.032	0.126	0.168
EE	8.73± 3.96	-0.279	0.236	0.023	0.697
UE	15.28± 3.17	-0.134	0.185	0.238	0.335
GERD questionnaire	3.56± 1.58	−0.150	0.300	0.450	0.001
EBBS questionnaire	10.80± 2.79	0.662	< 0.001	−0.250	0.080

Table 5. Correlation between 1-year %TWL and degree of residual gastric dilation with baseline data and follow-up information.

According to a report from the 7th International Federation for Surgery of Obesity and Metabolic Disorders (IFSO) in 2022, Laparoscopic Sleeve Gastrectomy (LSG) has become the most commonly performed bariatric surgical procedure worldwide, accounting for 61% of all bariatric surgeries¹⁸. The weight loss mechanisms of LSG are multifaceted, including accelerated gastric emptying, increased postprandial cholecystokinin secretion, increased blood plasma concentrations of GLP-1, and decreased ghrelin release^19–21. The most important mechanism of LSG is a reduction in gastric volume that limits food intake²². However, the residual gastric volume will expand over time, leading to a weakening of its restrictive effect, which is considered one of the reasons for inadequate weight loss and weight regain²³. The factors for secondary dilation of the residual gastric are not yet clear. This study explores the related factors for early postoperative dilation of residual gastric from the perspectives of clinical characteristics, surgical procedures, postoperative patient compliance, and dietary behaviors to help clinicians identify patients at high risk of sleeve dilation for early intervention and treatment.

This study employed CT scanning as the imaging technique to measure the residual gastric volume and its changes at 1 and 3 months post-LSG, aiming to investigates the associated factors contributing to residual gastric dilation and its impact on weight loss outcomes in LSG patients. CT scanning provides a rapid and accurate assessment of residual gastric volume compared to other imaging modalities²⁴, ²⁵. Although MRI is effective, it often requires a longer imaging duration, during which the fluid used to inflate the stomach may pass through the pylorus and empty, compromising the accuracy of the gastric volume assessment²⁶. Ultrasonography (USG) or upper gastrointestinal (UGI) contrast is quicker but introduces inaccuracy due to the operator-dependent nature of this modality²⁷, ²⁸. The residual gastric volume was measured 1 month after LSG surgery to allow sufficient time for early postoperative edema to subside considerably, thus avoiding interference with the volume measurement²⁹. Additionally, we ensured that patients consumed enough water to guarantee the fullness of the residual stomach. This approach, compared to other methods, better simulates normal physiological conditions and makes the measurement process simpler and more efficient.

Among the 50 patients we included, the residual gastric volume 1 month post-LSG was 161.77 ± 55.37 mL. By the third month post-LSG, the volume expanded to 174.43 ± 47.30 mL (p < 0.001), with an average expansion degree of 13.50 ± 17.35%. Notably, the correlation between the volume of the residual gastric and postoperative BMI and %TWL was weak and statistically insignificant. This finding is consistent with some previous research. Baumann et al. in a CT volumetric study, observed significant dilation of the residual gastric at 6 months and beyond, with volumes increasing from 105.3 ± 30.2 mL to 196.8 ± 84.3 mL (p = 0.038). However, they found no correlation between gastric volume and weight loss³⁰. In another CT volumetric study, Nam et al. also found that TSV was not correlated significantly with %TWL at 12 months post-LSG (r = − 0.069, P = 0.619)³¹.

Weight loss after LSG is largely attributed to the reduction of energy intake. However, the individual differences in residual gastric volume after LSG may not be the primary factor affecting the amount of food intake in patients after-LSG. Emanuel et al. divided patients after LSG into two groups: the residual stomach dilation group and the non-dilation group. They found that from 3 to 12 months after surgery, the total gastric volume increased from 189 ± 12 to 317 ± 21 mL (p < 0.00001) in the subjects with gastric dilation, whereas an insignificant increase was observed in the subjects without gastric dilation (236 ± 22 vs 208 ± 26 mL, p > 0.05). However, the daily caloric intakes were similar in both groups at 3, 6, 12, and 18 months after LSG, and there was no significant difference in weight loss between the two groups at 18 months post-LSG, which indicates that gastric volumes post-LSG may be not the critical determinants of the quantity of food that is eaten²⁹. Other factors such as satiety, nutrient absorption, alterations in gastric motility, and dietary behavior patterns also play a role.

Apart from limiting intake, there are many other factors may contribute to weight loss after LSG, including expansion of the residual gastric, gastric motility change, hormonal effects, and changes in eating habits. Therefore, this study further explored the factors related to weight loss at 12 months after surgery. We found that the factors associated with weight loss in this study were the preoperative BMI, inferior eating behavior (low CR score), MBSS score, and expansion of the residual gastric. The preoperative BMI in our study significantly correlated with %TWL at 1 year (r = 0.509, P < 0.001). Some other studies also have shown a similar relation³². This effect might occur because heavier individuals tend to perceive their own weight status more accurately, thereby improving treatment compliance and maintaining good dietary and exercise habits.

Obesity is known to be influenced by a complex psychological background. 51 to 70% of patients reported suboptimal adherence to food/lifestyle guidelines after bariatric surgery³³. Our findings indicate that a higher score on the EBBS questionnaire is associated with better weight loss outcomes. In a study by Giorgia et al. involving 41 patients, the EBBS questionnaire demonstrated good internal validity (p < 0.001). Furthermore, each item on the EBBS questionnaire was significantly correlated with weight-related outcomes (p < 0.001 for each item)¹⁶.

Patients experienced food intake restrictions caused by the LSG, which improve their dietary and exercise behaviors, leading to long-term weight loss. Several studies have examined the effects of LSG on the three dimensions of eating behavior—cognitive restraint, uncontrolled eating, and emotional eating—using the Three-Factor Eating Questionnaire (TFEQ). These studies found improvements in all three dimensions following LSG surgery³⁴. We further explored the correlation between these three dimensions and weight loss outcomes post-LSG surgery. We found that less weight loss at 12 months post-surgery was associated with lower scores in cognitive restraint.

This study found that at 3 months compared to 1 month postoperative, there was a statistically significant mild expansion of the residual gastric (161.77 ± 55.37 vs 173.43 ± 47.30 mL, p < 0.001), and this expansion was negatively correlated with TWL% at 1 year postoperative. Vidal et al reported a negative correlation between the increase in RGV and a weight loss after LSG¹². Clara et al. also found that the residual gastric volume increases almost twofold between the 1 and 5 year of the postoperative period with a significant weight regain³⁵. The possible reasons for the early expansion of the residual gastric volume may include the patients' eating habits, increased intraluminal pressure, and low compliance with the gastric tube.

This study found that excessively small residual gastric is associated with secondary expansion of the residual gastric. Emmanuel et al. also confirmed this view in their research, sleeve dilatation occurred especially in subjects with smaller total gastric volume at baseline (189 vs 236 mL, p = 0.02)²⁹. This may be related to intragastric hypertension caused by the narrow sleeve stomach. Patients with gastric dilatation have higher reflux scores, indirectly confirming this view. Seung found in his research that the volume of the residual gastric is positively correlated with food tolerance, and GERD symptoms are more likely to occur in patients with smaller residual gastric³⁶.

It is noteworthy that patients with preoperative diabetes are more likely to experience gastric dilatation. This could be secondary to diabetic gastropathy from autonomic neuropathy causing slowed gastric emptying. A study by Park et al compared gastric tissue from patients with and without diabetes mellitus after gastrectomy, and the results showed that those patients with diabetes mellitus had excessive amounts of fibrosis in their gastric smooth muscle and decreased density of interstitial cells of Cajal and platelet-derived growth factor receptor alpha, which are important for gastric motility. It is possible that diabetes-related delayed gastric emptying combined with chronic overdistention of the stomach is the reason patients with diabetes mellitus were found to have larger stomachs³⁷.

In summary, this study found that the residual gastric undergoes mild expansion within the early postoperative period (within 3 months) following LSG and is associated with weight loss at 12 months. An initial small volume of the sleeve, preoperative diabetes mellitus, and postoperative reflux are associated with a higher risk of sleeve dilatation. Our data showed the residual gastric volume or resected stomach volume is not necessarily linked to weight loss at 12 months. This may indicate that the size of a person’s stomach does not correlate with their weight loss success after LSG. Other factors, such as the pre-surgical BMI, secondary dilation of the remnant stomach, and postoperative dietary and treatment compliance might play a role in weight loss in the long term, and this should be considered in the surgical decision-making.

Acknowledgment of Funding or Funding Statement

This research received no external funding, thanks.

Francque SM, Marchesini G, Kautz A, Walmsley M, Dorner R, Lazarus JV, Zelber-Sagi S, Hallsworth K, Busetto L, Fruhbeck G, Dicker D, Woodward E, Korenjak M, Willemse J, Koek GH, Vinker S, Ungan M, Mendive JM, Lionis C. Non-alcoholic fatty liver disease: A patient guideline. JHEP Rep. 2021;3(5):100322.
Lobstein T. Obesity prevention and the Global Syndemic: Challenges and opportunities for the World Obesity Federation. Obes Rev. 2019;20 Suppl 2:6-9.
O'Kane M, Parretti HM, Pinkney J, Welbourn R, Hughes CA, Mok J, Walker N, Thomas D, Devin J, Coulman KD, Pinnock G, Batterham RL, Mahawar KK, Sharma M, Blakemore AI, Mcmillan I, Barth JH. British Obesity and Metabolic Surgery Society Guidelines on perioperative and postoperative biochemical monitoring and micronutrient replacement for patients undergoing bariatric surgery-2020 update. Obes Rev. 2020;21(11):e13087.
Angrisani L, Santonicola A, Iovino P, Ramos A, Shikora S, Kow L. Bariatric Surgery Survey 2018: Similarities and Disparities Among the 5 IFSO Chapters. Obes Surg. 2021;31(5):1937-1948.
Peterli R, Wolnerhanssen BK, Peters T, Vetter D, Kroll D, Borbely Y, Schultes B, Beglinger C, Drewe J, Schiesser M, Nett P, Bueter M. Effect of Laparoscopic Sleeve Gastrectomy vs Laparoscopic Roux-en-Y Gastric Bypass on Weight Loss in Patients With Morbid Obesity: The SM-BOSS Randomized Clinical Trial. JAMA. 2018;319(3):255-265.
Baheeg M, Elgohary SA, Tag-Eldin M, Hegab A, Shehata MS, Osman EM, Eid M, Abdurakhmanov Y, Lamlom M, Ali HA, Elhawary A, Mahmoud M, Basiony M, Mohammmed Y, Hasan A. Effect of laparoscopic sleeve gastrectomy vs laparoscopic Roux-en-Y gastric bypass on weight loss in Egyptian patients with morbid obesity. Ann Med Surg (Lond). 2022;73:103235.
Giannopoulos S, Kapsampelis P, Pokala B, Nault CJ, Hilgendorf W, Timsina L, Clapp B, Ghanem O, Kindel TL, Stefanidis D. Bariatric Surgeon Perspective on Revisional Bariatric Surgery (RBS) for Weight Recurrence. Surg Obes Relat Dis. 2023;19(9):972-979.
Clapp B, Wynn M, Martyn C, Foster C, O'Dell M, Tyroch A. Long term (7 or more years) outcomes of the sleeve gastrectomy: a meta-analysis. Surg Obes Relat Dis. 2018;14(6):741-747.
Langer FB, Bohdjalian A, Felberbauer FX, Fleischmann E, Reza HM, Ludvik B, Zacherl J, Jakesz R, Prager G. Does gastric dilatation limit the success of sleeve gastrectomy as a sole operation for morbid obesity? Obes Surg. 2006;16(2):166-171.
Deguines JB, Verhaeghe P, Yzet T, Robert B, Cosse C, Regimbeau JM. Is the residual gastric volume after laparoscopic sleeve gastrectomy an objective criterion for adapting the treatment strategy after failure? Surg Obes Relat Dis. 2013;9(5):660-666.
Benaiges D, Mas-Lorenzo A, Goday A, Ramon JM, Chillaron JJ, Pedro-Botet J, Flores-Le RJ. Laparoscopic sleeve gastrectomy: More than a restrictive bariatric surgery procedure? World J Gastroenterol. 2015;21(41):11804-11814.
Vidal P, Ramon JM, Busto M, Dominguez-Vega G, Goday A, Pera M, Grande L. Residual gastric volume estimated with a new radiological volumetric model: relationship with weight loss after laparoscopic sleeve gastrectomy. Obes Surg. 2014;24(3):359-363.
Hany M, Ibrahim M, Zidan A, Agayaby A, Aboelsoud MR, Gaballah M, Torensma B. Two-Year Results of the Banded Versus Non-banded Re-sleeve Gastrectomy as a Secondary Weight Loss Procedure After the Failure of Primary Sleeve Gastrectomy: a Randomized Controlled Trial. Obes Surg. 2023;33(7):2049-2063.
Noel P, Nedelcu M, Nocca D, Schneck AS, Gugenheim J, Iannelli A, Gagner M. Revised sleeve gastrectomy: another option for weight loss failure after sleeve gastrectomy. Surg Endosc. 2014;28(4):1096-1102.
Stunkard AJ, Messick S. The three-factor eating questionnaire to measure dietary restraint, disinhibition and hunger. J Psychosom Res. 1985;29(1):71-83.
Spaggiari G, Santi D, Budriesi G, Dondi P, Cavedoni S, Leonardi L, Delvecchio C, Valentini L, Bondi M, Miloro C, Toschi PF. Eating Behavior after Bariatric Surgery (EBBS) Questionnaire: a New Validated Tool to Quantify the Patients' Compliance to Post-Bariatric Dietary and Lifestyle Suggestions. Obes Surg. 2020;30(10):3831-3838.
Jones R, Junghard O, Dent J, Vakil N, Halling K, Wernersson B, Lind T. Development of the GerdQ, a tool for the diagnosis and management of gastro-oesophageal reflux disease in primary care. Aliment Pharmacol Ther. 2009;30(10):1030-1038.
ifso-7th-registry-report-2022. (Accessed September 4, 2022.). https://www.ifso.com/pdf/ifso-7th-registry-report-2022.pdf
Steenackers N, Vanuytsel T, Augustijns P, Tack J, Mertens A, Lannoo M, Van der Schueren B, Matthys C. Adaptations in gastrointestinal physiology after sleeve gastrectomy and Roux-en-Y gastric bypass. Lancet Gastroenterol Hepatol. 2021;6(3):225-237.
Sista F, Abruzzese V, Clementi M, Carandina S, Cecilia M, Amicucci G. The effect of sleeve gastrectomy on GLP-1 secretion and gastric emptying: a prospective study. Surg Obes Relat Dis. 2017;13(1):7-14.
Aukan MI, Skarvold S, Brandsaeter IO, Rehfeld JF, Holst JJ, Nymo S, Coutinho S, Martins C. Gastrointestinal hormones and appetite ratings after weight loss induced by diet or bariatric surgery. Obesity (Silver Spring). 2023;31(2):399-411.
Miras AD, le Roux CW. Mechanisms underlying weight loss after bariatric surgery. Nat Rev Gastroenterol Hepatol. 2013;10(10):575-584.
Velapati SR, Shah M, Kuchkuntla AR, Abu-Dayyeh B, Grothe K, Hurt RT, Mundi MS. Weight Regain After Bariatric Surgery: Prevalence, Etiology, and Treatment. Curr Nutr Rep. 2018;7(4):329-334.
Karcz WK, Kuesters S, Marjanovic G, Suesslin D, Kotter E, Thomusch O, Hopt UT, Felmerer G, Langer M, Baumann T. 3D-MSCT gastric pouch volumetry in bariatric surgery-preliminary clinical results. Obes Surg. 2009;19(4):508-516.
Robert M, Pechoux A, Marion D, Laville M, Gouillat C, Disse E. Relevance of Roux-en-Y gastric bypass volumetry using 3-dimensional gastric computed tomography with gas to predict weight loss at 1 year. Surg Obes Relat Dis. 2015;11(1):26-31.
Fiorillo C, Quero G, Dallemagne B, Curcic J, Fox M, Perretta S. Effects of Laparoscopic Sleeve Gastrectomy on Gastric Structure and Function Documented by Magnetic Resonance Imaging Are Strongly Associated with Post-operative Weight Loss and Quality of Life: a Prospective Study. Obes Surg. 2020;30(12):4741-4750.
LU Yanjia, HU Zhongqian, HUANG Yan, HAN Yudong, LI Jia, TAN Jiacheng. Measurement of Gastric Volume by Three-dimensional Ultrasound in Evaluating Efficacy of G-POEM Surgery of Patients with Postoperative Gastroparesis. Chinese Journal of Medical Imaging. 2019; 27:783-787.
Deregowska-Cylke M, Palczewski P, Blaz M, Cylke R, Ziemianski P, Szeszkowski W, Lisik W, Golebiowski M. Radiographic Measurement of Gastric Remnant Volume After Laparoscopic Sleeve Gastrectomy: Assessment of Reproducibility and Correlation with Weight Loss. Obes Surg. 2022;32(2):230-236.
Disse E, Pasquer A, Pelascini E, Valette PJ, Betry C, Laville M, Gouillat C, Robert M. Dilatation of Sleeve Gastrectomy: Myth or Reality? Obes Surg. 2017;27(1):30-37.
Baumann T, Grueneberger J, Pache G, Kuesters S, Marjanovic G, Kulemann B, Holzner P, Karcz-Socha I, Suesslin D, Hopt UT, Langer M, Karcz WK. Three-dimensional stomach analysis with computed tomography after laparoscopic sleeve gastrectomy: sleeve dilation and thoracic migration. Surg Endosc. 2011;25(7):2323-2329.
Nam KH, Choi SJ, Kim SM. Morphologic Study of Gastric Sleeves by CT Volumetry at One Year after Laparoscopic Sleeve Gastrectomy. J Metab Bariatr Surg. 2020;9(2):42-51.
Zhou L, Lin S, Zhang F, Ma Y, Fu Z, Gong Y, Hu D, Ma S, Ye X, Qian L, Geng X, Yang N, Liang H, Zhou H. The Correlation Between RDW, MPV and Weight Indices After Metabolic Surgery in Patients with Obesity and DM/IGR: Follow-Up Observation at 12 Months. Diabetes Ther. 2020;11(10):2269-2281.
Welch G, Wesolowski C, Zagarins S, Kuhn J, Romanelli J, Garb J, Allen N. Evaluation of clinical outcomes for gastric bypass surgery: results from a comprehensive follow-up study. Obes Surg. 2011;21(1):18-28.
Figura A, Rose M, Ordemann J, Klapp BF, Ahnis A. Changes in self-reported eating patterns after laparoscopic sleeve gastrectomy: a pre-post analysis and comparison with conservatively treated patients with obesity. Surg Obes Relat Dis. 2017;13(2):129-137.
Panella C, Busto M, Gonzalez A, Serra C, Goday A, Grande L, Pera M, Ramon JM. Correlation of Gastric Volume and Weight Loss 5 Years Following Sleeve Gastrectomy. Obes Surg. 2020;30(6):2199-2205.
Choi SJ, Kim SM. Intrathoracic Migration of Gastric Sleeve Affects Weight Loss as well as GERD-an Analysis of Remnant Gastric Morphology for 100 Patients at One Year After Laparoscopic Sleeve Gastrectomy. Obes Surg. 2021;31(7):2878-2886.
Park KS, Cho KB, Hwang IS, Park JH, Jang BI, Kim KO, Jeon SW, Kim ES, Park CS, Kwon JG. Characterization of smooth muscle, enteric nerve, interstitial cells of Cajal, and fibroblast-like cells in the gastric musculature of patients with diabetes mellitus. World J Gastroenterol. 2016;22(46):10131-10139.

No competing interests reported.

Analysis of Early Dilation of the Residual gastric After Laparoscopic Sleeve Gastrectomy: Insights from a 3D CT Reconstruction Study

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Abstract

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Key Points

Introduction

Patients and Methods