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CPT 43645: Gastric Bypass with Small Gastric Reservoir
CPT code 43645 represents a laparoscopic or open gastric bypass procedure in which a small gastric reservoir is created from the upper stomach and anastomosed to the small intestine to bypass the main stomach. This operation is a commonly performed bariatric surgical option for the treatment of morbid obesity and is clinically significant because it combines restriction and malabsorption to achieve sustained weight loss and improvement in obesity‑related comorbidities. Nationally, access, surgical utilization, and payer coverage policies for gastric bypass procedures influence patient selection and program capacity.
Key payers considered include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical intent and typical settings for the service, comparisons to related bariatric codes, and the diagnoses commonly associated with billing for this procedure. The publication also summarizes common payer coverage considerations and procedural benchmarks relevant to hospital and ambulatory surgical center billing, including typical ICD‑10 diagnoses used to support medical necessity. Policy updates, reimbursement benchmarks, and coding nuances that affect claim adjudication and site‑of‑service classification are addressed to inform revenue cycle and clinical leaders.
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Billing Code Overview
CPT code 43645 describes a surgical gastric bypass with creation of a small gastric reservoir using the upper stomach and connection to the small intestine to bypass the main stomach. The procedure is performed to treat morbid obesity, restricting stomach capacity and reducing nutrient absorption.
Service Type: Bariatric surgery — gastric bypass (Roux‑en‑Y) surgical procedure
Typical Site of Service: Inpatient hospital or ambulatory surgical center
National Reimbursement Benchmarks
Commercial averages for CPT 43645 sit above Medicare: BUCA’s mean commercial rate is $2,328.10 compared with Medicare’s mean of $1,727.10, a gap of $601.00 that illustrates materially higher negotiated commercial reimbursement versus the federal program. Several large commercial payers — Cigna and UnitedHealth Group in particular — post mean rates well above both BUCA and Medicare, creating a high-end market for this procedure.
Dispersion measured by the interquartile spread (P75 minus P25) varies meaningfully: Blue Cross Blue Shield has a spread of $1,328.60, Cigna $2,028.70, UnitedHealth Group $2,074.20, Aetna $817.30, and BUCA $1,484.30. Aetna shows the tightest IQR at $817.30, while UnitedHealth Group is the widest at $2,074.20, indicating the most variability in middle-range commercial payments.