Obesity is defined using Body Mass Index (BMI) (weight in kilograms divided by height in meters squared). Adult BMI categories cited include: Underweight <18.5; Normal 18.5–24.9; Overweight 25–29.9; Obesity Class I 30–34.9; Class II 35–39.9; Class III ≥ 40 kg/m2.
For adolescents, the ASMBS adolescent classifications are noted: Class II obesity defined as ≥120% of the 95th percentile or BMI 35–39.9 kg/m2 (whichever is lower) and Class III obesity defined as ≥140% of the 95th percentile or BMI ≥40 kg/m2 (whichever is lower). Growth charts and CDC BMI-for-age references are used for pediatric assessment.
A multidisciplinary bariatric team should include specialties such as a bariatric surgeon, obesity medicine specialist, registered dietitian, specialized nursing, behavioral health specialist, exercise specialist, and support groups; MBSAQIP accreditation and multidisciplinary assessment are emphasized for programs and revisional-surgery evaluation.
Common bariatric surgical procedures described include: Roux-en-Y gastric bypass (RYGB) (creation of a small stomach pouch and bypass of stomach/duodenum), laparoscopic adjustable gastric banding (LAGB) (inflatable silicone band around proximal stomach), vertical sleeve gastrectomy (VSG/SG) (resection of ~60–75% of stomach creating a tubular sleeve), and biliopancreatic diversion with duodenal switch (BPD/DS) (malabsorptive operation with a short common channel).
Revisional bariatric surgery is defined and subclassified: a conversion changes the index procedure to a different bariatric operation (not an intraoperative conversion), a corrective procedure addresses complications or incomplete treatment effect without changing the initial operation, and a reversal restores original anatomy. The policy references MBSAQIP processes and the need for thorough multidisciplinary reassessment prior to revisional procedures.
Robotic-assisted surgery is noted as an available technique that can offer three-dimensional vision and increased dexterity for precision dissection, and transoral/endoscopic approaches (NOTES and transoral restorative techniques) are described as investigational or evolving approaches under study.
Endoscopic therapies covered in background include: Endoscopic Sleeve Gastroplasty (ESG) using an endoscopic suturing system (e.g., OverStitch) to reduce gastric capacity, TransPyloric Shuttle (TPS) (a space-occupying, tethered device approved for up to 12 months in specified BMI ranges), intragastric balloons (IGBs) (acid-resistant balloons filled with saline or air, typically maximum placement six months), gastrointestinal liners (EndoBarrier/DJBL), stomach aspiration therapy (AspireAssist), bariatric artery embolization (BAE), and gastric electrical stimulation (GES/CLGES) and vagus nerve blocking (VBLOC) neuromodulation. Many of these endoscopic and device therapies are noted as under investigation with variable evidence quality.