Relationship Between Residual Gastric Area and Weight Loss After Sleeve Gastrectomy: a Cohort Study
Conditions: Obesity, Morbid
Sponsor: University of Foggia

 
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RELATIONSHIP BETWEEN RESIDUAL GASTRIC AREA 
AND WEIGHT LOSS AFTER SLEEVE GASTRECTOMY: A 
COHORT STUDY 
 
 
RUNNING HEADS: Imaging after laparoscopic sleeve gastrectomy 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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ABSTRACT 
 
BACKGROUND: The aim of this study is to evaluate the impact of the actual size and 
area of the remnant stomach, as measured by Upper gastrointestinal tract radiography, 
on weight loss after sleeve gastrectomy.  
 
MATERIALS AND METHODS: From May 2017 to December 2019, 56 patients with 
morbid obesity were admitted to the Department of Medical and Surgical Sciences, 
University of Foggia and underwent laparoscopic sleeve gastrectomy.  
 
RESULTS: 56 patients underwent sleeve gastrectomy with a mean age of 43,5 ± 11 years 
of which 40 were female. The mean Excess Weight Loss (EWL) at 1 month was 24,09 ± 
15,04 %, at 6 months was 27,07 ± 19,55 % and at 12 months was 69,9 ± 23,7 %. The 
mean Excess Body Mass Index Loss (EBMIL) at 1 month was 23,1 ± 12,5%, at 6 
months was 56,6 ± 19,7% and at 12 months was 69,7 ± 23,7 %. 
The EWL % was correlated with the residual stomach area (RSA) at 1 month (r=-0,242 
p=0,072), at 6 months (r=-0,249 p=0,064) and at 12 months (r=-0,451 p= 0,0005). 
The EBMIL % was correlated with the RSA at 1 month (r = -0,270; p = 0,043 ), at 6 
months (r = -0,270; p = 0,043) and at 12 months (r = -0,46; p = 0,0004). 
 
CONCLUSION: A greater postoperative EWL % was correlated with a smaller RSA 
and this resulted in a statistically significant change at 12 months after surgery.  
 
 
 
 
 
Key words: laparoscopic sleeve gastrectomy, EWL, UGI radiography 
 

 
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INTRODUCTION 
 
Obesity is a rising global epidemic that places significant strain on healthcare services 
worldwide. Morbid obesity is associated to complications affecting nearly every organ , 
resulting in a decrease in life expectancy [1-3]. 
In the last few years, various international guidelines and systematic reviews have 
confirmed laparoscopic sleeve gastrectomy (LSG) as a definitive and stand-alone 
procedure for morbid obesity [4-7]. 
LSG is perceived as one of the safest bariatric operations. The main advantages of LSG 
include: a relatively simple surgical technique with no need of anastomosis creation, 
short learning curve and low rate of metabolic complications [8]. 
Within bariatric surgery, it is common that radiologists must deal with the interpretation 
of images of patients after LSG. There are differences in peri and postoperative care 
protocols and likewise with the approach to the imaging algorithm. 
Upper Gastrointestinal (UGI) tract radiography with water-soluble contrast medium is 
the most basic study after LSG. This minimally invasive technique has a long history of 
being used for the detection of both early and late postoperative complications [9, 10].  
A normal postoperative UGI series will show free flow of contrast into the gastric 
remnant, which is tubular with no spillage of contrast beyond the staple line, which is 
located on the caudal aspect of the gastric remnant. Stenosis or obstruction of the 
stomach may occur if the stomach remnant is too tight or with torsion of the 
stomach[11]. 
In the literature most of the authors studied the correlation between postoperative 
gastric volume and percent excess weight loss (EWL) [12, 13]. The size of the remnant 
stomach with respect to weight loss after LSG remains controversial.  
The aim of this study is to evaluate the impact of the actual size and area of the remnant 
stomach, as measured by Upper gastrointestinal tract radiography, on weight loss after 
LSG. 
 
 

 
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MATERIALS AND METHODS 
 
Study design and setting  
 
From May 2017 to December 2019, 56 patients with morbid obesity were admitted to 
the Department of Medical and Surgical Sciences, University of Foggia and underwent 
laparoscopic sleeve gastrectomy. UGI tract radiography with water-soluble contrast 
medium was performed on the second day after the operation to rule out leakage. The 
radiographic images were collected through a software program called “PACS” which 
combined with a viewer for image processing, allows for the calculation of the residual 
stomach area (RSA). RSA was correlated with postoperative weight (EWL) at 1, 6, and 
12 months (Figure 1). The UIN for ClinicalTrial.gov Protocol Registration and Results 
System is:1 for the Organization UFoggia. 
 
Figure 1: UGI tract radiography collected through a software called “PACS” 
 
 
Eligibility criteria  
 
Adult patients of both genders with morbid obesity defined as BMI>40 kg/m2 or 
BMI>35 kg/m2 with at least one associated major comorbidity were included. We 
excluded patients with secondary obesity due to endocrine and  psychological disorders, 

 
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patients with previous bariatric procedures and patients unwilling to comply with 
postoperative diet and exercise program.  
 
Statistical analysis  
 
Continuous data were expressed as mean and standard deviation (SD) and they were 
analyzed using Student’s T test. The correlation between gastric volume before and after 
LSG and BMI and weight loss was measured using Pearson correlation coefficient test. 
Correlation coefficients were classified as strong (-1.0 to -0.5 or 0.5 to 1.0), moderate (-
0.5 to -0.3 or 0.3 to 0.5), and weak (-0.3 to -0.1 or 0.1 to 0.3). P<0.05 was considered 
statistically significant. This work is fully compliant with the STROCSS criteria [14]. 
 
RESULTS 
 
56 patients underwent sleeve gastrectomy with a mean age of 43,5± 11 years of which 40 
were female. The mean preoperative weight was 127,5 ± 19,8 kg and the preoperative 
mean Body Mass Index (BMI) was 45,5± 5,57 kg/m2. The mean residual stomach area 
(RSA) was 64,8 ± 16,5 cm2(Table 1).  
 
 
Table 1: Demographic and operative characteristics of the study groups  
Age (years) mean ± (SD)  
43,5 ± 11  
Sex: n male / female 
16/40  
Height (cm)mean±(SD) 
167 ± 9,3  
Preoperative weight  (Kg) mean±(SD)  
127,5 ± 19,8 
Preoperative BMI (kg/m2) mean ±(SD)  
45,5 ± 5,57  
Residual Stomach Area (cm2) mean±(SD)  
64,8 ± 16,5  
SD: Standard Deviation 
 

 
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The mean Excess Weight Loss (EWL) at 1 month was 24,09 ± 15,04 %, at 6 moths was 
27,07 ± 19,55 %, at 12 months was 69,9 ± 23,7 %. The mean Excess Body Mass Index 
Loss (EBMIL) at 1 month was 23,1 ± 12,5 %, at 6 months was 56,6 ± 19,7 %, at 12 
months was 69,7 ± 23,7 % (Table 2). 
 
 
 
Table 2: % EWL mean - % EBMIL mean 
% EWL mean -  % EBMIL mean 
% EWL 1 month (mean) ±(SD)  
24,09 ± 15,04 
% EWL 6 months (mean) ±(SD)  
27,07 ± 19,55 
% EWL 12 months (mean) ±(SD)  
69,9 ± 23,7 
% EBMIL 1 month (mean) ±(SD)  
23,1 ± 12,5 
% EBMIL 6 months (mean) ±(SD)  
56,6 ±19,7 
% EBMIL 12 months (mean) ±(SD)  
69,7 ± 23,7 
SD: Standard Deviation EWL: Excess Weight Loss  EBMIL: Excess Body Mass Index Loss  
 
The EWL % was correlated with the RSA at 1 month (r=-0,242 p=0,072), at 6 months 
(r = -0,249 p = 0,064) and at 12 months (r = -0,451 p = 0,0005) (Graphic 1, 2, 3). 
 
 
 
 
Graphic 1 : % EWL 1 month – Pearson correlation – p value 

 
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Graphic 2 : % EWL 6 months – Pearson correlation – p value 
 
 
Graphic 3 : % EWL 12 months – Pearson correlation – p value 

 
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The EBMIL % was correlated with the RSA at 1 month (r = -0,270; p =0,043 ), at 6 
months (r = -0,270; p = 0,043) and at 12 months (r = -0,46; p = 0,0004) (Graphic 4, 5, 
6). 
 
 
Graphic 4: % EBMIL 1 month – Pearson correlation – p value 
 
 
Graphic 5: % EBMIL 6 months – Pearson correlation – p value 

 
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Graphic 6: % EBMIL 12 months – Pearson correlation – p value 
 
 
DISCUSSION 

 
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LSG has become a popular technique in the treatment of morbid obesity owing to the 
satisfactory outcome as recently demonstrated in the SM-BOSS randomized trial which 
concluded that LSG and Roux-Y-gastric bypass are equally effective regarding short and 
mid-term weight loss, improvement in comorbidities, and complications [15]. 
Nevertheless, LSG can still be associated with failure to achieve significant EWL or 
failure to sustain weight loss with eventual weight regain at long-term follow-up [16]. 
LSG is a volume-restrictive procedure, the volume of remaining gastric pouch after LSG 
and the volume of the resected stomach were studied as possible causes of inappropriate 
weight loss or weight regain after the procedure [17–21] (Figure 2). 
 
 
 
 
 
 
 
 
 
Figure 2: Excised stomach 

 
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Elbanna et al. used CT volumetry for measuring the gastric volume before and 
immediately after LSG to assess the correlation of gastric volumes pre- and 
postoperatively and weight loss at 6 months after the procedure. They concluded that 
the size of the remaining gastric pouch and the percentage of the resected stomach had 
significant impact on % EWL after LSG [22]. 
Salman MAA et al. used multidetector computed tomography (MDCT) to measure 
preoperative stomach volume and cuff volume. The actual resected gastric volume was 
measured after surgery. The primary outcome was the relationship between residual 
gastric volume and percentage of excess body weight loss (% EBWL) after 3 and 6 
months. The secondary outcome was early postoperative complications. They concluded 
that gastric volume removed during LSG was significantly correlated with weight 
reduction after 3 and 6 months of surgery. Sleeve volume was not correlated with early 
weight reduction. MDCT is a reliable method of measuring gastric volume before and 
after surgery [23]. 

 
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Hanssen et al. analyzed thirty patients who underwent LSG and were followed 
prospectively and evaluated at 6 months after the surgical procedure, performing 3D CT 
reconstruction and gastric volumetry, to establish its relationship with EWL. A 
significant relationship between gastric volume (GV) and EWL 6 months after LSG was 
established, demonstrating that GV ≥ 100 ml at 6 months of LSG is associated with 
poor EWL [24]. 
In recent years, CT has been increasingly used as a primary postoperative examination 
after bariatric procedures for the detection of complications. There are many studies in 
the literature that analyze the potential relationship of residual gastric volume with 
excess weight loss in patients with sleeve gastrectomy. The main concern associated with 
the use of CT is its high radiation dose. 
The advantages of UGI radiography compared to CT include the speed of the 
procedure, the reduced associated costs, shorter waiting times for the patient and lower 
dose of radiation to which the patient is exposed. There is a significant difference in 
terms of absorption of radiation between the 3DCT and the direct abdomen, 7.8mSV vs 
1mSV (Figure3). 
Figure3: UGI tract after LSG 
 
 
 
The present study has some limitations that include a small sample size, the single-center 
nature of the study and the short follow-up duration.  
 
 
 

 
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CONCLUSION  
 
A greater postoperative EWL % was correlated with a smaller RSA and this is 
statistically significant at 12 months after surgery (p<0,05). Although in the literature the 
standard for the relationship with post LSG weight loss is a volumetric measurement 
through 3DCT, the study of the RSA by UGI radiography could provide an important 
alternative, with an advantage demonstrated in terms of reduction of radiation absorbed 
by the patient, speed of procedure and reduction of costs to the NHS. Larger studies 
over a longer period of time are needed to confirm these findings. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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Provenance and peer review 
Not commissioned, externally peer-reviewed