ORIGINAL CONTRIBUTIONS
Evaluation of the Efficacy of Single Anastomosis Sleeve Ileal (SASI)
Bypass for Patients with Morbid Obesity: a Multicenter Study
Tarek Mahdy
1
& Sameh Hany Emile
1
& Amr Madyan
1
& Carl Schou
2
& Abdulwahid Alwahidi
3
& Rui Ribeiro
4
&
Alaa Sewefy
5
& Martin Büsing
6
& Mohammed Al-Haifi
7
& Emad Salih
8
& Scott Shikora
9
#
Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract
Background Single anastomosis sleeve ileal (SASI) bypass is a newly introduced bariatric and metabolic procedure. The present
multicenter study aimed to evaluate the efficacy of the SASI bypass in the treatment of patients with morbid obesity and the
metabolic syndrome.
Methods This is a retrospective, seven-country, multicenter study on patients with morbid obesity who underwent the SASI
bypass. Data regarding patients’ demographics, body mass index (BMI), percentage of total weight loss (%TWL), percentage of
excess weight loss (%EWL), and improvement in comorbidities at 12 months postoperatively and postoperative complications
were collected.
Results Among 605 patients who underwent the SASI, 54 were excluded and 551 (390; 70.8% female) were included. At 12
months after the SASI, a significant decrease in the BMI was observed (43.2 ± 12.5 to 31.2 ± 9.7 kg/m
2
; p < 0.0001). The %TWL
was 27.4 ± 13.4 and the %EWL was 63.9 ± 29.5. Among the 279 patients with type 2 diabetes mellitus (T2DM), complete
remission was recorded in 234 (83.9%) patients and partial improvement in 43 (15.4%) patients. Eighty-six (36.1%) patients with
hypertension, 104 (65%) patients with hyperlipidemia, 37 (57.8%) patients with sleep apnea, and 70 (92.1%) patients with
GERD achieved remission. Fifty-six (10.1%) complications and 2 (0.3%) mortalities were recorded. Most complications were
minor. All patients had 12 months follow-up.
Conclusions The SASI bypass is an effective bariatric and metabolic surgery that achieved satisfactory weight loss and improve-
ment in medical comorbidities, including T2DM, hypertension, sleep apnea, and GERD, with a low complication rate.
* Sameh Hany Emile
Sameh200@hotmail.com
Tarek Mahdy
tmahdy@yahoo.com
Amr Madyan
profamoora@gmail.com
Carl Schou
cfschou@online.no
Abdulwahid Alwahidi
Abdulwahid66@hotmail.com
Rui Ribeiro
ruijsribeiro@gmail.com
Alaa Sewefy
Sewafy@yahoo.co.uk
Martin Büsing
Martin.buesing@yahoo.de
Mohammed Al-Haifi
Dr_alhaifi@hotmail.com
Emad Salih
Emadtahir73@yahoo.com
Scott Shikora
sshikora@bwh.harvard.edu
1
General Surgery Department, Mansoura Faculty of Medicine,
Mansoura University Hospitals, Mansoura University, 60
El-Gomhoria Street Dakahlia, Mansoura 35516, Egypt
2
Aker University Hospital, Oslo, Norway
3
Sharjah University Hospital, Sharjah, United Arab Emirates
4
Clinica De Santo Antonio, Lusiadas, Amadora, Lisbon, Portugal
5
General Surgery Department, Minia Faculty of Medicine, Minia
University, Minya, Egypt
6
Klinikum Vest, Dorstenerstr, 151, 45657 Recklinghausen, Germany
7
Sidra Hospital, Riggae Area, Kuwait
8
Atakent Hospital, Istanbul, Turkey
9
Brigham and Women’s Hospital, Harvard Medical School,
Boston, USA
Obesity Surgery
https://doi.org/10.1007/s11695-019-04296-3
Keywords Sleeve
.
Ileal
.
Single
.
Anastomosis
.
SASI
.
Bypass
.
Multicenter
.
Morbid obesity
Introduction
Obesity and type 2 diabetes mellitus (T2DM) have become major
public health problems [1] and bariatric surgery is now recognized
to be the most effective treatment for T2DM in obese patients [2].
Malabsorptive procedures represent a common strategy in
bariatric surgery. Most of the malabsorptive bariatric opera-
tions employ non-specific malabsorption that leads to poten-
tial deficiencies of several nutrients such as iron and folic acid
[3]. On the other hand, bariatric procedures that involve diges-
tive tract bypassing may result in atrophy of the mucosa as
demonstrated by flattening of the villous surface area and an
increase in the mitotic frequency [4].
As the digestive physiology is increasingly under investi-
gation, the interacting neuroendocrine signals that control
hunger, satiety, and energy expenditure are better understood.
The m yriad of potential complications observed with the
malabsorptive procedures has driven investigators to develop
new, less complicated alternatives [5].
The ideal bariatric procedure does not currently e xist.
Hypothetically, it would modulate the neuroendocrine control
of hunger and satiety without inflicting any harm to important
digestive functions unrelated to obesity such as gastrointestinal
motility, peristalsis, and enzyme secretion. Based on this con-
cept, in 2003, Santoro et al. [6] introduced a sleeve gastrectomy
procedure with transit bipartition (SG þ TB). The SG þ TB is
similar to the duodenal switch (DS) but does not completely
exclude the duodenum in order to minimize nutritional compli-
cations. The SG þ TB amplifies the nutritive stimulation of the
distal gut while diminishing the exposure of the proximal bowel
to nutrients without excluding the duodenum and jejunum as
hasbeenreportedintheliterature[5–10].
The single anastomosis sleeve ileal (SASI) bypass (Fig. 1)
is a simplified modification of the SG þ TB that entails a single
loop anastomosis rather than Roux-en-Y double anastomosis.
It may be assumed that the reduction in the number of intes-
tinal anastomoses may be associated with less anastomotic
complications and shorter operative time. However, a random-
ized trial directly comparing the SASI bypass and the SG þ TB
is required to substantiate this assumption.
A possible explanation of the mechanism of action of the
SASI bypass was devised by Mahdi et al. [11] that patients who
undergo the SASI bypass eat less food because they experience
early satiety due to a hypothalamic-generated satiety sensation
which is caused by the perception of nutrients in the distal
bowel [12]. The intense distal gut stimulation reduces proximal
bowel activity. The distal gut hormones such as GLP-1 have
central satietogenic effects, and they also reduce gastric empty-
ing which is known as the ileal break mechanism [13].
The first report on the efficacy of the SASI bypass in pa-
tients with morbid obesity demonstrated excellent results of
the new procedure [11]. The present multicenter study aimed
to evaluate the short-term efficacy of the SASI bypass in the
treatment of patients with morbid obesity and the metabolic
syndrome in terms of weight loss and remission of T2DM.
Patients and Methods
Study Design
This is a retrospective, multicenter study of patients with mor-
bid obesity with or without T2DM who underwent the SASI
bypass in the period of Janu ary 2014 to January 2018.
Prospective data were collected from eight centers located in
seven countries (UAE = 37, Kuwait = 36, Egypt = 275,
Germany = 63, Norway = 71, Portugal = 19, and Turkey =
50). Central ethical approval for the study was obtained by the
principal investigator from the Research Ethics Committee
(code=MOHAP/DXB-REC//MAA/No.15/2019).
Procedures Implemented to Maintain Confidentiality
of Participant’sData
Only the research team was eligible to access the data which
was kept anonymous. Responses to the research were reported
in aggregated form to protect the identity of respondents. For
the purpose of confidentiality, no names of patients were men-
tioned in the manuscript.
Fig. 1 Schematic demonstrat ion of single anastomosis sleeve ileal
(SASI) bypass
OBES SURG
Subject Selection
Adult patients (18–60 years) of both sexes with morbid obe-
sity were included. Morbid obesity was defined as a body
mass index (BMI) of greater than 40 kg/m
2
or greater than
35 kg/m
2
with at least one associated comorbidity. We exclud-
ed patients with a previous upper abdominal laparotomy or
psychological instability. Patients who did not fulfill at least
12 months of follow-up were also excluded from the study.
Study Outcome Measures
The primary outcomes of the study were as follows:
& The percentage of total weight loss (%TWL): calculated
as [(preoperative weight − weight at twelve months)/pre-
operative weight] × 100.
& The percentage of excess weight loss (%EWL): calculated
as: [(preoperative weight − weight at twelve months)/pre-
operative excess weight] × 100.
& Complete remission of T2DM was defined as a fasting
plasma glucose level < 100 mg/dl or HbA1C level < 6%
without the use of hypoglycemic medication at 1 year after
surgery.
& A partial improvement in T2DM was defined as a reduc-
tion of at least 25% of the fasting plasma glucose level and
of at least 1% in the hemoglobin A1c level with the use of
hypoglycemic medications [14].
Secondary outcomes were as follows:
& Remission of hypertension was considered if the disease
was controlled and the patients was normotensive (BP <
120/80) off antihypertensive medication [14].
& Remission of hyperlipidemia was defined as normal lipid
profile off medications [14].
& Remission of sleep apnea was defined as AHI/RDI of less
than five off CPAP/BI-PAP on repeat objective testing
with polysomnography [14].
& Remission of GERD was defined as absence of symp-
toms, no medication use, and normal 24-h pH study [14].
& Postoperative complications were defined as “an undesir-
able and unintended result of the operation affecting the
patient that occurs as a direct result of the operation.”
& Changes in nutritional status.
Preoperative Assessment and Preparation
All patients had a preoperative evaluation including careful
history taking, clinical examination, and laboratory investiga-
tion including blood glucose, lipid profile, and a thyroid and
cortisol hormonal evaluation. The diagnosis of T2DM was
based on fasting blood glucose concentrations > 126 mg/dl
or those patients with a positive history of diabetes and taking
antidiabetic medications.
For each of the obesity-related comorbidities, the following
tests were used for diagnosis: T2DM: Fasting and postprandi-
al blood glucose and HBA1c; hypertension: arterial blood
pressure measurement on three different occasions under rest-
ing conditions; dyslipidemia: serum triglyceride, cholesterol,
LDL, VLDL, a nd HDL level; sleep apnea: STOP-BANG
questionnaire and sleep study (polysomnography); and
GERD: endoscopy and 24-hour pH study.
Routine gastroscopy or gastrografin studies were also per-
formed. Abdominal ultrasounds were done to exclude gall-
stones and to evaluate the degree of fatty liver. The liver size
was reduced by keeping all patients on a low-calorie protein
diet for 2 weeks prior to surgery. Deep vein thrombosis pro-
phylaxis started 12 h before surgery with low molecular
weight heparin subcutaneous injections.
Surgery
The patient is placed on the operating table in the French
position. General anesthesia with endotracheal intubation is
performed. The first part of the operation is performed with
the patient in a steep reverse-Trendelenburg position and the
surgeon standing between the legs of the patient.
The technique commences with the devascularization
of the greater curvature of the stomach. The dissection
then is continued toward the gastroesophageal junction.
The left crus is then completely freed of any attach-
ments to avoid l eaving a posterior pouch when con-
structing the sleeve. Posterior attachments between the
stomach and pancreas are then divided.
The stomach is then tabularized over a 36-French calibra-
tion tube, with a linear cutting stapler, commencing 6 cm
proximal to the pylorus. The staple line is then oversewn with
a running suture. The table is then changed to the horizontal
position and the surgeon moves to the left-hand side of the
patient to perform the second part of the operation.
The ileocecal junction is identified and a point 250 cm
proximal to the ileocecal valve is measured. The selected in-
testinal loop is then brought up to the gastric sleeve without
division of the greater omentum. A stapled isoperistaltic side-
to-side anastomosis to the anterior wall of the antrum of the
stomach is done using a linear cutting stapler, 6 cm proximal
to the pylorus. The diameter of the anastomosis should not
exceed 3 cm in diameter. The anterior wall of the gastroileal
anastomosis is closed with a two-layer running suture. A
methylene blue test is the performed to assess for leaks.
Ambulation and clear liquids are started on the night of
surgery. Thrombosis prophylaxis is continued for 4 weeks.
Proton pu mp inhi bitors are admin istrated for 4 months
postoperatively.
OBES SURG
Follow-up
The study patients were seen as outpatients 2 weeks postop-
eratively then every month for 12 months. Patients were also
seen in the clinic if they developed symptoms between their
follow-up visits. The endpoint of the study was at 1 year after
SASI bypass. When patients reached this time point, they
were contacted by email or telephone to visit the clinic for
follow-up in terms of weight loss and improvement in comor-
bidities. Patients who failed to respond at this time point were
excluded from the study.
Study patients were placed on a low-caloric, protein-rich
liquid diet for the first month and then other elements were
sequentially introduced under strict dietitian supervision. The
patients were asked to take multivitamin supplements that
included a minimum of 18 mg of iron, 400 mcg of folic acid,
800 to 1,000 IUs of vitamin D, and 500 mcg of vitamin B
12
on
daily basis. The supplement also included calcium, selenium,
copper, and zinc. Patients were encouraged to initiate physical
activity after the first postoperative week. All patients had a
complete blood investigation every 3 months and gastroscopy
every 6 months.
Assessments
At 12 months of follow-up, patient weights were measured.
The %TWL, %EWL, and BMI were calculated. Remission or
partial improvement in T2DM and other comorbidities were
record ed. Remission of T2DM was assessed by means of
clinical and laboratory parameters; the clinical parameters in-
cluded reduction of the dose or stoppage of insulin or hypo-
glycemic medications with normally maintained blood glu-
cose levels. The laboratory parameters were fasting blood glu-
cose < 100 mg/dl and HBA1c < 6%.
The fasting blood sugar level, HbA1c, serum albumin, se-
rum hemoglobin, serum iron, and serum vitamin D were mea-
sured and compared with their baseline values. Early and de-
layed procedure-related complications were also recorded.
Data Collected
For each participating center in this study, there was one per-
son (one of the authors) who performed the SASI bypass and
carried out the data collection. Patient and outcome data were
stored in an electronic registry. The data were checked for
accuracy and were verified before their collection and extrac-
tion into Excel sheets. Finally, all authors sent their data in an
Excel sheet format to the first author (T.M.). The data man-
agement team (second and third authors) conducted a second
check of the data for completeness and accuracy. Patients with
missing or incorrect data were excluded from the study.
Preoperative data including patient age, gender, initial
weight, BMI, excess body weight, and obesity-related
comorbidities such as T2DM, hypertension, cardiac ischemia,
hyperlipidemia, obstructive sleep apnea syndrome (OSAS),
the presence of gallstones, joint pain, depression, infertility,
and heartburn were recorded.
Operative data were recorded includ ing intraopera tive
complications such as bleeding, organ injury, specimen re-
trieval problems, and stapler malfunction. Postoperative data
collection included %TWL, %EWL, change in BMI, and ear-
ly postoperative complications that occurred during the first
month such as infections, bleeding, vomiting, leak, and port
site problems. Long-term complications beyond 1 month after
surgery such as vomiting, reflux, stricture, intestinal obstruc-
tion, hypoalbuminemia, anemia, iron, and vitamin D deficien-
cy were also collected.
Statistical Analysis
Data were analyzed using IBM® SPSS® (version 21.0 for
Windows). Unless stated otherwise, all data were expressed
as the mean ± standard deviation (SD) or as percentages.
Descriptive and inferential statistical analyzes were performed
using both parametric and non-parametric procedures as ap-
propriate. Comparisons of categorical/ordinal variables were
performed using chi-square analysis for trends. Continuous
variables were compared using student t test. Multiple linear
regression analysis was performed to determine the significant
independent predictors for higher %TWL after SASI bypass.
All tests were two-tailed, and the results with p <0.05were
considered statistically significant.
Results
Patients’ Characteristics
After screening the records of 605 patients who underwent the
SASI bypass in the study period, 54 did not meet the inclusion
criteria of the study or had missing data, thus were excluded.
Ultimately, 551 patients from eight participating centers were
included in the study. Three hundred ninety patients were
female (70.8%) and 161 (29.2%) were male. The mean age
of the patients was 39.1 ± 14.7 (range, 18–60) years. The
mean preoperative BMI was 43.2 ± 12.5 (range, 35–80) kg/
m
2
. The mean preoperative weight was 119.3 ± 37.9 (range,
73.6–234) kg and the mean preoperative height was 165.2 ±
8.5 (range, 144–193) cm.
A total of 279 patients had T2DM (77.7% were on insulin
and 22.3% were on oral antidiabetic medications), 238 had
hypertension, 160 had hyperlipidemia, 64 had OSAS, and
76 had gastroesophageal reflux disease (GERD). Fifty-eight
(10.5%) of the patients underwent the SASI bypass as a rescue
procedure after a failed sleeve gastrectomy. The characteristics
of the study patients are shown in Table 1.
OBES SURG
Weight Loss at 12 Months
The %TWL was 27.4 ± 13.4 (range, 9–56) and the %EWL
was 63.9 ± 29.5 (range, 24.5–98.8). At 12 months after the
SASI bypass, a significant decrease in BMI was observed
(from 43.2 ± 12.5 to 31.2 ± 9.7 kg/m
2
; p < 0.0 001).
Similarly, preoperative body weight was also significantly de-
creased at 12 months of follow-up (from 119.3 ± 37.9 to 86.4
± 29.6 kg) (Table 2).
Improvement in Comorbidities
Among 279 patients with T2DM, complete remission was
recorded in 234 (83.9%) patients and partial improvement in
43 (15.4%) patients. Therefore, a total of 277 (99.3%) patients
showed either complete remission or partial improvement in
their glycemic state after SASI bypass.
Patients who developed complete remission of T2DM
showed a significant decrease in fasting blood g lucose
(228.4 ± 103.4 to 100.4 ± 16.1 mg/dl, p < 0.0001) and a
significant decrease in HbA1c (8.1 ± 3.6 to 5.3 ± 2.6; p <
0.0001). Serum C-peptide level increased significantly from
1.37 ± 0.8 to 1.6 ± 1.3 ng/ml (p =0.02).
Similarly, patients who showed partial improvement in the
glycemic state showed significant decrease in fasting blood
glucose (186.3 ± 73.1 to 120.2 ± 43.8 mg/dl, p < 0.0001)
and a significant decrease in HbA1c (7.6 ± 3.5 to 5.6 ± 2.6;
p = 0.003). Serum C-peptide level increased from 0.65 ± 0.17
to 0.69 ± 0.35 ng/ml (p =0.5).
Eighty-six (36.1%) of 238 patients with hypertension, 104
(65%) of 160 patients with hyperlipidemia, 37 (57.8%) of 64
patients with OSAS, and 70 (92.1%) of 76 patients with
GERD showed remission after having the SASI bypass.
Improvements in obesity-related comorbidities were all statis-
tically significant as shown in Table 3.
Changes in the Nutritional Status After SASI Bypass
Changes in laboratory parameters reflecting the nutritional
status at 12 months after SASI b ypass included a non-
significant increase in hemoglobin levels (p = 0.23), a signif-
icant decrease in serum iron levels (p = 0.02), a significant
decrease in serum albumin levels (p = 0.007), and a significant
increase in vitamin D levels (p < 0.0001). Despite the decrease
in serum albumin levels, none of the patients had protein mal-
absorption postoperatively and the average serum albumin
level after SASI was within normal range (3.9 g/dl) (Table 4).
Complications and Readmission
There were fifty-six (10.1%) complications after the SASI
bypass. Four (0.72%) patients required readmission within
30 days after surgery. Postoperative morbidities included bil-
ious vomiting (n =32),diarrhea(n =15),stomalulcer(n =3),
calcular obstructive jaundice (n = 2), pulmonary embolism (n
= 1), intestinal obstruction (n = 1), staple line bleeding (n =1),
and ileal perforation (n =1).
Bilious vomiting and diarrhea were treated conservatively with
fluids and medications. Stomal ulcers were managed with proton
pump inhibitors, and calcular obstructive jaundice was treated with
ERCP and stone extraction, whereas staple line bleeding, intestinal
obstruction, and ileal perforation required surgical intervention.
One patient who developed a pulmonary embolism was admitted
to the ICU and was treated with intravenous fluids, anticoagulant
medications, and thrombolytic therapy .
Overall, according to the Clavien-Dindo classification,
there were 47 (84%) grade I complications, three (5.3%) grade
II complications, five (8.9%) grade III complications, and one
(1.7%) grade IV complication (Table 5).
Outcome of the SASI Bypass as a Rescue Procedure
After Sleeve Gastrectomy
Fifty-eight patients underwent the SASI bypass as a rescue sur-
gery after sleeve gastrecto my. Patients were 35 (57.6%) female
and 23 (42.4%) male. The mean age of these patients was 41.8 ±
10.5 years. The mean preoperative height was 162 ± 6.9 cm. Ten
(17.2%) patients had T2DM, 24 (41.4%) had hypertension, three
(5.1%) had dyslipidemia, and three (5.1%) had OSAS.
Table 2 Weight loss at 12 months after SASI bypass
Variable Preoperative Postoperative P value*
Mean body mass index 43.2 ± 12.5 31.1 ± 9.7 < 0.0001
Mean body weight in kg 119.3 ± 37.9 86.2 ± 29.7 < 0.0001
%Total weight loss ------ 27.4 ± 13.4 -----
%Excess weight loss ------ 63.9 ± 29.5 -----
*Unpaired Student t test was used for data analysis
Table 1 Preoperative characteristics of the patients studied
Va riab le Va lue
Number 551
Female/male 390/161
Mean age in years 39.1 ± 14.7
Mean body mass index in kg/m
2
43.2 ± 12.5
Mean weight in kg 119.3 ± 37.9
Mean height in cm 165.2 ± 8.5
Diabetes mellitus 279 (50.6%)
Hypertension 238 (43.2%)
Hyperlipidemia 160 (29%)
Sleep apnea 64 (11.6%)
Gastroesophageal reflux disease 76 (13.8%)
Previous sleeve gastrectomy 58 (10.5%)
OBES SURG