Robotic Single Anastomosis Duodenal-ileal Bypass With Sleeve Gastrectomy (SADI-S) for Morbid Obesity: A Systematic Review
Literature search. A literature search was conducted on PubMed, Scopus and Cochrane Library to identify studies based on the inclusion and exclusion criteria. The following search strings were used: (“Single anastomosis duodenal ileal bypass” (Title/Abstract) OR “SADI” (Title/Abstract) OR “SADI-S” (Title/Abstract) OR “Robotic SADI-S” (Title/Abstract) OR “Robotic SADI” (Title/Abstract) OR “bariatric surgery” (Title/Abstract) OR “sleeve gastrectomy” (Title/Abstract)) AND (“Robotic Surgical Procedures” (Title/Abstract) OR “Robotics” (Title/Abstract) OR “Robotics” (MeSH)). As part of the comprehensive research approach, the reference lists of pertinent review articles or meta-analyses were examined to uncover additional eligible studies. The entirety of the search was conducted in the English language, ensuring thorough comprehension, consistency, and accessibility. Inclusion and exclusion criteria. Studies were included if they met the following criteria: (a) population: obese human adults (age ≥18 years); (b) intervention: robotic single anastomosis duodenal-ileal (SADI) bypass with sleeve gastrectomy; (c) outcomes: clearly reporting BMI reduction; (d) study design: reviews, meta-analyses, case series and case reports including at least three patients; (e) manuscript language: English or English translation available. The exclusion criteria were as follows: (a) duplicate reports of a study; (b) studies with insufficient data (e.g., lacking clear reporting of patient demographics or incomplete documentation of postoperative complications); (c) case reports including less than three patients; (d) non-English manuscripts with no translation provided; (e) poster presentations and/or articles with no full text available. Study selection and data extraction. Two independent reviewers (TK, KE) separately conducted data screening and extraction, with a third reviewer (CD) invited to resolve discrepancies in case of discordant assessments. Duplicate articles were identified and eliminated, and the reviewers evaluated the titles and abstracts of the remaining articles, which were excluded from further review if both reviewers deemed them unsuitable. Full-text articles were scrutinized when one reviewer opted for inclusion or when insufficient information in the title and abstract hindered decision-making. Key data, including publication year, author details, trial design, sample size, and patient demographics (e.g., sex, disease type, mean age), were compiled into a predefined table. Additionally, intervention specifics, such as duration, treatment techniques, risk of bias, and outcome data were recorded. Study selection. Initially, 300 studies were identified using the search terms (250 from PubMed, 16 from Scopus and 34 from Cochrane Library). After removing duplicates, 13 studies were excluded. Screening titles or abstracts led to the exclusion of 273 records. Subsequently, full texts of the remaining 14 articles were reviewed for accuracy, resulting in the exclusion of seven articles. Ultimately, seven studies met the inclusion criteria. The literature selection process is depicted in the flow diagram in . 

Study characteristics. Seven studies elucidated the outcomes of robotic-assisted SADI-S in 204 patients ( - ). All studies were published between 2015 and 2024. Two studies were conducted in Spain (28.57%), two in the United States (28.57%), two in Italy (28.57%) and one in China (14.29%). Most operations concerned primary SADI-S (173 cases, 84.8%) and the rest (31 cases, 15.2%) were revisional. summarizes the risk of bias assessment for all seven studies. Intraoperative complications, conversion rates and mortality. Among the 204 patients operated, only a single (0.49%) intraoperative complication regarding minor bleeding was reported (B). In no case did the surgeons have to convert to laparoscopic/open SADI-S. The overall mortality among studies was found to be nil. Operative time. The interval from the initial incision to the final skin-to-skin surgical site closure defines the operative time (OT). Varying mean operative times were reported, ranging from 138 to 205.7 minutes. Although Qudah et al. reported a mean OT of 110 min ( ), this duration only represents true robotic console use-associated time; the duration of crucial time-consuming parts of the operation, including docking and undocking times- were not measured. It is noteworthy that the mean OT for the SSO robotic-assisted SADI-S subgroup was more than 30 min shorter than that for the SO subgroup (172.7 vs. 205.7 min, respectively), according to the results of Marincola et al. ( ). More details about each study’s mean OT are provided in . Length of hospital stay and readmission. The median hospital stay duration ranged from 2 to 6.7 days, with more than half of studies reporting the bottom extremum. Post-operative complications on the second postoperative day had elongated the length of stay for two cases reported by Marincola et al. to a total of seven and nine days each ( ). Readmission rates were minimal, with just one (0.49%) patient readmitted to the hospital with a post-operative complication (although unspecified), concerning the learning stage group (i.e., the first 27 patients operated) of Wang et al.’s series ( ). Postoperative complication rates. Several studies reported early (<30 days) postoperative period results. Out of the 204 patients described, 13 cases (6.37%) developed postoperative complications; seven (3.43%) were classified as Clavien-Dindo grade II (two cases of pneumonia, one haemorrhage, one seroperitoneum, one delayed gastric emptying, and one duodenal-ileal anastomotic leakage), three (1.47%) were classified as Clavien-Dindo grade III (one trocar site hernia and two gastric leakages), two (0.98%) were classified as Clavien-Dindo grade IV (one postoperative acute respiratory failure and one incarcerated incisional trocar site hernia), and the details about the last (0.49%) complication were not disclosed. The management of these complications incorporated both conservative and surgical interventions; the seroperitoneum, abdominal bleeding, delayed gastric emptying and duodenal-ileal anastomotic leakage were successfully managed conservatively; the two gastric leakages necessitated reoperation, while the patient who developed acute respiratory failure was transferred to the Intensive care unit (ICU) for further treatment; the 43-year-old patient (BMI=54.6 kg/m 2 ) who developed an incarcerated incisional trocar site hernia [diagnosed following an abdominal computed tomography (CT) scan due to repeated bile vomiting and localised periumbilical trocar site pain on the second postoperative day] needed an exploratory laparoscopy for hernia reduction and subsequent ICU hospitalisation for a single day, to be discharged five days later; lastly, the 62 year-old woman (BMI=51.4 kg/m 2 ) who developed pneumonia (diagnosed following an abdominal and chest CT scan with per os (PO) and intravenous (IV) contrast due to fever with no abdominal pain on the second postoperative day) improved clinically following IV antibiotic administration, to be discharged a week later. No late (>30 days) postoperative complications (e.g., chronic diarrhoea, malnutrition, Wernicke-Korsakoff’s syndrome, toxic megacolon) were described in any of the studies. At their 12-months-follow-up, no patient presented any complication. Weight loss. Results regarding post-surgical weight loss are mentioned in four studies. The mean preoperative BMI ranged from 34.9 to 62.9 kg/m 2 (SSO patients). Wang et al. reported a mean EWL of 113.74% at a 24-month follow-up ( ), while Pennestrì et al. reported a mean EWL of 67.1% at a 25-month follow-up ( ). A mean total body weight (TBW) loss of 12.7% at a median 4.5-month follow-up was described by Qudah et al. ( ). Vilallonga et al. observed a BMI reduction of 6.3, 13.5, and 2.9 kg/m 2 for two patients at a nine-month follow-up and another patient at a three-month follow-up, respectively ( ). One study only reported a mean pre-operative BMI of 50 kg/m 2 with no reference to post-operative weight loss; one study provided no details regarding both pre- and post-operative BMI, while the study classifying patients into SO and SSO subgroups only pointed to initial BMI values (55.6 and 62.9 kg/m 2 , respectively), with no information regarding post-operative weight loss disclosed. The characteristics of the included studies are summarized in Table I. 

The conception of SADI-S has revolutionised bariatric surgery since its introduction in 2007 as a refinement of the more complex biliopancreatic diversion with duodenal switch (BPD/DS), in an effort to simplify while improving its efficacy in terms of weight loss and metabolic disease (e.g., type 2 diabetes) remission and reduce the operative risk by eliminating one of the anastomoses. Although laparoscopy has been traditionally employed to perform SADI-S, a notable shift toward integrating robotic systems has been recently noted; robotic platforms offer even greater precision, flexibility, and control, providing surgeons with enhanced visualisation through 3D high-definition views and more dexterous instrument manipulation, mimicking human hand movements but with a range of motion beyond natural capabilities. The robotic-assisted SADI-S procedure requires the patient to be initially placed in reverse Trendelenburg position with both legs and arms open. The first 8 mm optical trocar is inserted at the lower or upper edge of the navel and the camera is used. A second 12 mm stapler trocar is inserted at the level of the junction of the right anterior axillary line and the right end of the greater curvature of the stomach. A third 8mm trocar that is placed at the junction of the mid-clavicular line costal margin can be used as a liver retractor. Finally, a fourth 8 mm trocar is inserted at the level of the left axillary line, under the costal margin. All trocars are placed 8 cm apart under visual inspection. The intra-abdominal structures are assessed, the terminal ileum is identified, and the mobility of the small bowel is evaluated. The pylorus and duodenum are mobilised, and the retroduodenal window is created. The small bowel is traced retrograde from the ileocecal junction for a length of 250-300 cm using a tape measure and a mark with sutures is placed at the spot. SG is performed 2-4 cm away from the pylorus and a boogie is used to complete it. Transection of the duodenum is performed at 2 cm from the pylorus. Finally, a duodenal-ileal anastomosis is performed at the marked spot. The anastomosis is completed by using a continuous absorbable suture ( ). The limited number of studies identified, alongside their significant recency (<10 years) reflect the early stages of development of this robotic-assisted technique. The available data are predominantly composed of small, retrospective, single-institution series, the largest of which barely exceeds 100 patients. It is remarkable that all operations in those series were successful, with a total intraoperative complication rate of less than 0.5% and nil deaths, highlighting the primary safety of the technique and robotic integration. The latter is crucial considering mortality rates reported by studies assessing the outcomes of laparoscopic SADI-S, which can be as high as 0.5%-0.6% ( , ). Furthermore, the absence of conversion to laparoscopic or open surgery underscores the superior manoeuvrability the robotic platform provides, aiding to surpass technical barriers and difficulties associated with laparoscopic anastomosis performance (occasionally a reason of conversion to open) ( ). Ergonomic benefits allow for comfortable operating from a console while seated, reducing fatigue and hand tremors, enhancing surgical precision, and reducing the likelihood of errors that could lead to complications ( ). One of the few disadvantages of robotics in surgery is perhaps the longer duration of the procedure; the included studies report mean operative times almost as high as 3 hours and 30 minutes, while laparoscopic SADI-S does not usually exceed 2 hours and 20 minutes ( ), as the main part of the operation can be initiated immediately following trocar insertion. While the true console time for robotic SADI-S may appear shorter ( ), robotic systems require additional, time-consuming setup that can underestimate the total operative time. Surgeons specialising in robotic upper gastrointestinal surgery can experience shorter completion times as the familiarise themselves with the system’s interface and controls and improve their proficiency over time. This delay in total operative time in robotic surgeries is noted in almost all types of surgery; for example, a recent systematic review of randomised controlled trials comparing laparoscopic versus robotic abdominal and pelvic surgery reported significantly prolonged total operative times in the robotic group ( ). However, robotic-assisted SADI-S allows for shorter hospitalisation times compared its laparoscopic counterpart, as enhanced dexterity reduces tissue trauma, and improved visualisation permits better anatomical structure identification and more meticulous dissection. Literature reports shorter hospital stays and accelerated recovery for robotic- over laparoscopic-assisted bariatric surgery ( ); Pennestrì et al. reported a mean postoperative hospital stay duration of one day shorter in patients who underwent robotic SADI-S as opposed to the laparoscopic group (2.0 vs. 3.0 days, respectively) ( ). Generalising, robotic-assisted RYGB seems to be favourable in terms of overall length-of-stay compared to laparoscopic RYGB ( , ), however other studies comparing robotic to laparoscopic bariatric surgery (RYGB, SG, DS) identified no significant difference ( , ). Nevertheless, the validity of these findings may be limited by the relatively small sample sizes or single-centre studies available. Regarding readmission, we have found a rate less than half of that reported in literature ( ). Postoperative complication rates for laparoscopic SADI-S can reach 15% ( ) and include leaks at the duodeno-ileal anastomosis, gastric stable line, and, less frequently, duodenal stump, with a risk just below 2% according to meta-analyses ( ). Other systematic reviews have reported complication rates ranging from 4.8% to 6.1% following SADI-S ( , ), which are significantly higher than postoperative complication rates after robotic SADI-S; these disparities are a result of enhanced precision and accuracy afforded by robotic systems, minimising the likelihood of complications and readmission. The null incidence of late postoperative complications (leaks, strictures, nutritional deficiencies) following robotic-assisted SADI-S highlights its safety compared to traditional approaches ( ) and potential to enhance patient satisfaction, improve quality of life, and reduce healthcare resource burden by minimising the need for costly and invasive interventions to address postoperative issues. As weight loss highly depends on the type of procedure, similar weight loss results for both laparoscopic and robotic SADI-S groups would be expected. A few studies report that the former seems to induce greater %EWL, although their results were not significant ( ). Other analyses observed robotic SADI-S outcomes (including %EWL) compatible to those previously reported for the laparoscopic approach ( ). Compared to other bariatric surgeries, however, SADI-S induces remarkably greater weight loss ( , ) due to the more extensive intestinal bypass that maximises calory and nutrient malabsorption. Pyloric valve preservation allows for more natural gastric emptying and may result in improved tolerance to difference foot textures and downscale dumping syndrome, promoting weight loss and dietary adherence long-term sustainability. Long-term follow-up is essential to evaluate SADI-S surgical success and pertains to a period of two years at best in most studies. It allows for optimal-accuracy weight loss maintenance assessment over time and enables for closer metabolic health parameter monitoring (beyond weight loss), as SADI-S favourably impacts the progression of multiple obesity comorbidities (hypertension, dyslipidaemia, type 2 diabetes). Despite minimal initial complications, adverse effects, such as nutritional deficiencies, anastomotic strictures, and bowel obstruction may manifest years after SADI-S, therefore statistical analysis of late long-term follow-up data will allow for complication rate trend identification and effective management and punctual prevention strategy development. Furthermore, incorporating validated quality-of-life assessment tools into long-term follow-up protocols can facilitate holistic benefit (physical-social functioning, early mobilisation, mental health) quantitative assessment. Finally, long-term follow-up data can contribute to evidence-based decision making and clinical guideline establishment to optimise outcomes ( ). There are no specific selection criteria for robotic SADI-S to date; BMI should be principally considered, as those with BMI >35 or 40 kg/m 2 may benefit from bariatric surgery ( ). Comorbidity evaluation, such as type 2 diabetes, hypertension, or obstructive sleep apnoea is crucial ( ), and mental health support may also be necessary. While age alone should not exclude patients, it is important to consider one’s overall health status, as younger individuals with severe obesity and significant comorbidities may benefit more from SADI-S ( ). Anatomical assessments may help evaluate gastrointestinal tract suitability and variation investigation can impact surgical feasibility ( ). Perioperative nutritional assessment is vital to identify patients in need of preoperative vitamin D, folate acid, iron, calcium, vitamin B12, or albumin supplementation ( ), while personal preferences, expectations, and goals must be discussed to enhance satisfaction and compliance through shared decision-making ( ). Risk-benefit analysis consider potential risks weighted against weight loss and metabolic improvement benefits ( ), while surgeon experience and proficiency should also be taken into account ( ). Lastly, multidisciplinary collaboration (surgeons, endocrinologists, nutritionists, psychologists) ensures comprehensive patient care and outcome optimisation ( ). The considerations for primary versus revisional SADI-S are another hot topic, as those undergoing primary surgery have typically not undergone prior weight loss procedures and may present with severe obesity and significant metabolic comorbidities. However, revisional surgery is indicated for patients with inadequate weight loss or regain following previous operation and requires careful consideration of anatomical alterations and potential complications ( ). Revisional SADI-S presents unique anatomical challenges due to altered gastrointestinal anatomy and scar tissue from prior surgeries, therefore managing patient expectations regarding postoperative outcomes is essential ( ). Regarding cost-effectiveness, Wang et al. found that long-term outcomes are associated with cost savings due to reduced complications and hospital stays despite the higher initial cost for robotic surgery ( ). Hospitals that invest in robotic surgery programs can achieve a positive return on investment within a few years. This is largely due to reduced readmissions, which optimize the use of healthcare resources, minimize the need for additional procedures (such as imaging and consultations), and ultimately lower overall healthcare costs. However, continued development and refinement of cost-effectiveness models specific to robotic SADI-S are necessary to provide policymakers and healthcare administrators with evidence-based guidance for resource allocation and technology adoption. Study limitations. Our sample (seven studies, 204 patients) may not fully represent the broader population undergoing robotic-assisted SADI-S. Several studies carry a risk of type II error, most are observational, and publication bias remains a possibility. Additionally, the studies primarily come from a few countries (Spain, the United States, Italy, and China), which limits the generalizability of the findings to other healthcare systems and populations with different demographics and practices. Restricting the analysis to English-only studies may have excluded relevant research published in other languages (language bias). Moreover, the inter-study variability in patient demographics and outcome measures may further complicate the synthesis of results and hinder the ability to draw definitive conclusions. Follow-up duration is perhaps insufficient to assess long-term outcomes and complications, while the absence of comparison groups / control arms in some studies renders the attribution of observed outcomes solely to robotic SADI-S challenging. Finally, although efforts were made to define clear inclusion and exclusion criteria, certain relevant studies may have been inadvertently excluded due to overly restrictive criteria. Addressing the above limitations in future research is essential to improve evidence validity, generalisability, and applicability in clinical practice and decision-making. 

The transformative inception of SADI-S signifies a major advancement in bariatric surgery, enhancing the traditional approach with improved safety, efficacy, and patient outcomes. The integration of robotic systems offers unparalleled precision, reduced operative risks, and potentially shorter hospital stays, underscoring the significant benefits over conventional laparoscopic methods. However, the emerging nature of this technology, reflected in the limited number of studies and their recentness, highlights the need for extensive research to fully establish its long-term efficacy, cost-effectiveness, and impact on patient quality of life. Future directions should focus on comparative studies, the standardization of outcome measures, and the integration of advanced technologies to further refine and optimize robotic SADI-S, promising a new era in the management of morbid obesity and associated metabolic disorders. 

The Authors declare that the present study received no funding. 

The Authors declare that there are no conflicts of interest associated with this manuscript. 

Conceptualization and Design: T.K. and C.D. formulated the research question, designed the review methodology, and established the inclusion and exclusion criteria. Search Strategy Development: T.K. developed the search strategy, including selecting databases and determining search terms. Literature Search and Screening: T.K. and K.E. conducted the literature search. T.K and E.K. independently screened titles and abstracts for relevance and performed the full-text screening of potentially eligible studies. Data Extraction: T.K. and K.E. extracted data from the included studies, including study characteristics, outcomes, and quality assessments. Quality Assessment: T.K. and C.K. assessed the quality of the included studies using the Cochrane Risk of Bias tool. Data Analysis and Synthesis: K.E. conducted the statistical analysis and meta-analysis. E.K. synthesized the findings and drafted the results section. Manuscript Writing: T.K. drafted the manuscript, with K.E. writing the introduction and methods sections. T.K and K.E. contributed to the discussion and conclusion sections. Critical Review and Editing: C.D., T.T., N.G, and D.D. critically reviewed the manuscript, provided feedback, and contributed to revisions. Project Administration: T.K, C.D, and D.D. coordinated the project and managed communication between Authors. Funding Acquisition: There was no funding in the creation of this manuscript. Approval of the Final Manuscript: All Authors (T.K., E.K., C.D., N.G., G.T., S.K., E.K., C.K., T.T., and D.D) reviewed and approved the final version of the manuscript before submission. 

