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Page 10 of 13 Pennestrì et al. Mini-invasive Surg. 2025;9:16 https://dx.doi.org/10.20517/2574-1225.2025.03

We are aware that the primary SADI-S is a niche surgery. The main indication for the primary SADI-S
includes patients with classes IV and V obesity, especially in the presence of comorbidities. The
contraindications are consistent with those applicable to all malabsorptive procedures, including organ
[12]
transplantation, severe renal and hepatic impairment, intestinal bowel disease, and celiac disease . On the
other hand, suboptimal clinical response or weight gain after another bariatric surgery poses indications for
conversion to SADI-S. In addition, SADI-S can be planned as a two-stage procedure in selected patients,
such as class IV or V obesity or cases with intraoperative findings justifying this approach (hepatomegaly or
severe intra-abdominal adhesions), as well as in comorbid complex cases without a higher BMI risk but an
increased risk of postoperative complications. There is still no consensus in the literature [38-40] regarding the
interval between the two procedures in a planned two-stage surgery, which can vary from 12 months to
[15]
several years .
Closely related to these aspects, some technical considerations about the operation must be addressed. In
our previous studies, we defined SADI-S as a complex bariatric procedure given that it is performed in
challenging patients such as obesity classes IV and V. In addition, a multi-quadrant abdominal exploration
and hand-sewn anastomotic reconstruction are required [6,20] . Laparoscopy presents some technical
restrictions in class V obese patients. Transection of the duodenum can be difficult, and a single
anastomosis is carried out between the duodenum and the ileum using an end-to-side hand-sewn
technique. Enhanced proficiency and accuracy in tissue handling, especially in anatomically challenging
areas, are the main advantages of a robotic platform, especially in complex multi-quadrant procedures like
SADI-S. Therefore, robotic platforms might be the optimal technology for SADI-S-eligible patients with
class V obesity . Regrettably, illustrating certain benefits of robotic technology, such as less surgeon
[41]
fatigue, is intricate due to their inability to be linked with a measurable metric.

Nevertheless, we first demonstrated the safety of the robotic approach to SADI-S compared to the
laparoscopic one regarding postoperative complications . Despite that, our recent analysis confirms that
[20]
robotic SADI-S has been associated with longer OTs.

Lastly, we analyzed the procedure’s learning curve regarding TO using the CUSUM analysis, identifying a
[20]
change point after the first 61 cases. Our previous manuscript described the learning curve for both
laparoscopic and robotic procedures, indicating that the OT for robotic SADI-S significantly decreased after
7 cases, whereas the OT for laparoscopic SADI-S decreased after 47 cases. However, we could not identify a
definitive inflection point in the learning curves for laparoscopic SADI-S. It is also important to consider
the sequence in which the different procedures were conducted at our center. Notably, the eighth robotic
SADI-S case was performed after 60 laparoscopic cases, suggesting a likely cumulative and cross-influential
learning effect between the two modalities . Similar to our findings, Wang et al. reported that 58 cases
[20]
were required to overcome the learning curve for robotic SADI-S . Nonetheless, it must be pointed out
[23]
that all procedures in our study were performed by a single surgeon, which limits the generalizability of
results. It is therefore key to note that results may vary depending on the surgical team or institutional
context.

This study has several limitations that should be noted. First, it is a retrospective study over a long period.
Given that SADI-S is a niche procedure, we would like to emphasize the small sample size and
heterogeneous follow-up. The median follow-up duration was approximately 2 years, with only a small
proportion of patients followed for 5 and 7 years (41.4% and 8.3%, respectively). Therefore, the long-term
results should be interpreted with caution. Nevertheless, to our knowledge, this is the first national, single-
center retrospective study reporting 8 years of experience with this bariatric surgery.