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The bipartition principle · Sleeve gastrectomy + transit bipartition

SASI
in Mexico (Cancún).

SASI joins a sleeve gastrectomy with an intestinal transit bipartition: it combines a restrictive, a malabsorptive, and a neuroendocrine/metabolic component in a single operation.

The bipartition principle: part of the food reaches the ileum earlier and triggers intestinal signals (GLP-1, PYY) that regulate hunger and glucose, while the rest keeps its normal path through the duodenum. This adds a metabolic component to the restrictive effect of the sleeve — with a single connection.
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Dr. David Lomelí en quirófano
In the OR · Hospital Joya, Cancún

01 · What it is

Sleeve gastrectomy + transit bipartition. Restriction and metabolic signaling.

Diagrama del SASI: manga gástrica con anastomosis al íleon
~80% of stomach resected

SASI (Single Anastomosis Sleeve Ileal) combines a sleeve gastrectomy with a transit bipartition. I perform a conventional sleeve gastrectomy, removing approximately 75–80% of the stomach, and add a connection that lets part of the food reach the ileum earlier while another part keeps its normal path through the duodenum.

That early passage to the ileum activates intestinal hormones (GLP-1, PYY) that regulate hunger and glucose — the neuroendocrine component. The portion that continues through the duodenum and jejunum preserves absorption.

A single connection, versus two in a classic Roux-en-Y gastric bypass (RYGB). It combines the restrictive effect of the sleeve with an intestinal bypass component and a metabolic signal. The final indication depends on your clinical evaluation.

02 · Who it's for

A specific procedure for selected patients.

It is a specific procedure that is not indicated for everyone; that is why we must assess your case first. SASI may be considered in selected patients with BMI ≥40, or BMI ≥35 when comorbidities such as diabetes, hypertension, high cholesterol, or high triglycerides are present.

≥40

BMI ≥40

Obesity with BMI ≥40, with or without associated metabolic disease.

≥35

BMI ≥35 with comorbidity

BMI ≥35 accompanied by conditions such as diabetes, hypertension, high cholesterol, or high triglycerides.

✓

Clinical evaluation

The final indication depends on your full clinical evaluation and a detailed informed consent, which we review in consultation before deciding.

If your case calls for robust 10+ year evidence — for example, long-evolution type 2 diabetes — an established option like gastric bypass or sleeve may suit you better. We define that together in consultation, before deciding.

03 · The procedure

From first consult to discharge. What happens, step by step.

~90–120 minutes in the OR · 1–2 nights in hospital
01

Pre-operative evaluation

Cardiology and anesthesia evaluation, nutritional assessment with a clinical nutritionist, psychological evaluation with bariatric psychology, and a detailed informed consent reviewing the procedure, its scope, and the available evidence.

02

Surgery day

Laparoscopic operation under general anesthesia. Resection of 75–80% of the stomach in vertical sleeve, followed by creation of a single side-to-side anastomosis between the gastric antrum and a loop of ileum. Approximate operative time: 90–120 minutes.

03

Hospital recovery

1–2 nights in hospital. Early ambulation within 24 hours. Start of clear-liquid diet under supervision. Daily medical visit until discharge.

04

Post-surgical stay

If you're from outside Cancún, 3 additional days are recommended before flying home. Hotel near the hospital, WhatsApp follow-up and fluid monitoring.

05

Dietary protocol

Typical progression: clear liquids → full liquids → puree → soft solids over approximately 6 weeks. Nutritional support throughout the transition.

06

Long-term follow-up

In-person or virtual visits at month 1, 3, 6, and 12, then annually. Because long-term evidence is still being built, nutritional and outcome monitoring matters more, not less.

04 · Outcomes

What we already know. And what we still don't.

SASI has shown favorable short-term results. Its main current limitation is that there are still few studies with medium- and long-term follow-up, especially beyond 5 years and in large patient groups. For that reason, IFSO considers it an innovative/investigational procedure that should be evaluated carefully, with individual assessment, detailed informed consent, and close follow-up.

65–80%

Excess weight loss at year 1

Range reported in published case series (Mahdy et al. International Journal of Surgery 2016; Emile et al. systematic review, Langenbeck's Archives of Surgery 2024).

—

Type 2 diabetes remission

Early case series report high remission rates, but sample sizes are small and follow-up is limited. We do not commit to a specific percentage until evidence matures.

>5y

Long-term data

There are still few studies with follow-up beyond 5 years and in large patient groups. That is why long-term nutritional and outcome monitoring matters more, not less.

Sources: Mahdy et al. (International Journal of Surgery 2016, original SASI description); Emile et al. (Langenbeck's Archives of Surgery 2024, systematic review); Brown et al., Innovative Bariatric Procedures and Ethics in Bariatric Surgery: the IFSO Position Statement, Obesity Surgery 2022.

05 · Benefits

Benefits of SASI. Advantages, without overstating.

When SASI is the right option — and we decide that together in consultation — it can offer concrete advantages. I am not saying it is "better" than other techniques: in the right patient, it adds useful features.

1×

A single anastomosis

One surgical join, instead of the two in techniques like the classic bypass (RYGB). When clinically appropriate, it can be a simpler procedure.

R+M

Restriction + metabolic effect

Combines the restrictive component of the sleeve with an intestinal and neuroendocrine/metabolic effect.

endo

Preserves endoscopic access

Keeps the route for endoscopic inspection of the duodenum and biliary tree, unlike techniques that exclude it.

↺

Potentially reversible

The gastro-ileal anastomosis can be reversible if the case requires it.

None of these advantages replaces careful patient selection or detailed informed consent. Evidence beyond 5 years in large cohorts is still limited compared with bypass (RYGB) or sleeve, and the final indication depends on your clinical evaluation.

06 · Cost

I don't publish prices. Here's why.

Each case has a different risk profile, hospital choice, length of stay, and follow-up program. Publishing a single number would be dishonest — it would either undersell complex cases or overprice simple ones.

WhatsApp me your weight, height, and any medical conditions. I respond within 24 hours with a real quote, hospital recommendation, and financing options if you need them.

Get a quote on WhatsApp →

07 · SASI vs Bypass

SASI or bypass? Depends on how much evidence you demand.

SASI · This page

When SASI is considered

  • Complex metabolic profile where you want to combine the restrictive effect of the sleeve with an intestinal component.
  • A single anastomosis versus the two in Roux-en-Y gastric bypass (RYGB).
  • Patients who have reviewed the scope of the procedure and the available evidence with their surgeon, with detailed informed consent.
  • You understand that long-term evidence in large cohorts is still limited compared to RYGB or sleeve.
Gastric Bypass

When bypass wins

  • You need long-term evidence (>10 years) — RYGB is the most studied bariatric procedure.
  • Type 2 diabetes with >10-year follow-up in literature — RYGB has STAMPEDE and other consolidated studies.
  • Severe reflux or grade C/D esophagitis — RYGB is the better-established option.
  • You want a procedure accepted as standard by ASMBS and the major international societies.

Ask me about Gastric Bypass on WhatsApp →

08 · Frequently asked

Your questions deserve honest answers.

SASI joins a sleeve gastrectomy with a transit bipartition: a single new connection between the stomach and the ileum. A restrictive effect plus an intestinal and metabolic bypass component, using one surgical join versus the two in RYGB. Its long-term evidence in large cohorts is still limited compared with bypass or sleeve.
Published case series report ~65–80% of excess weight at 1 year (Mahdy 2016; Emile 2024 systematic review). Data at 5+ years are not yet robustly published. Your outcome depends on adherence and your specific case — we evaluate it in consultation.
Safety in any bariatric surgery comes from three things: surgeon credentials, hospital accreditation, and the follow-up program. I am board-certified by CMCOEM, an active member of ASMBS and IFSO, and I operate in accredited hospitals (Joya, Amerimed, Galenia). SASI is a specific procedure for selected patients; its main limitation is that evidence beyond 5 years in large cohorts is still limited. In consultation we assess whether it is the best option for your case or whether one with more years of evidence (RYGB or sleeve) is more appropriate.
Varies by hospital (Joya, Amerimed, or Galenia), length of stay, and follow-up program. I don't publish a single number because it would be dishonest — it would either undersell complex cases or overprice simple ones. WhatsApp me for a real quote within 24 hours, along with financing options if you need them.
1–2 nights in hospital. Ambulation within 24 hours. Liquid → soft → solid diet over approximately 6 weeks. Return to office work typically in 2 weeks, physical activity in 4–6 weeks. WhatsApp open from the moment you wake up in recovery.

Next step

SASI is not for everyone. And we don't operate until we're sure.

WhatsApp me your weight, height, and any medical conditions. I respond personally with an honest assessment — including whether an alternative with more evidence (RYGB or sleeve) would be more appropriate for your case.

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