Bariatric Surgery CPT Code Framework
Bariatric surgery billing centers on a small number of high-value procedure codes, each with specific documentation requirements tied to BMI thresholds, comorbidity documentation, and prior authorization. The three primary procedures (Roux-en-Y gastric bypass, sleeve gastrectomy, and adjustable gastric banding) each have distinct CPT codes, and the choice of laparoscopic versus open approach changes the code selection. Incorrect code assignment on a $15,000 to $25,000 procedure creates significant revenue loss that cannot be recovered through volume.
Gastric Bypass Codes (43644, 43645, 43846, 43847)
Laparoscopic Roux-en-Y gastric bypass is reported with CPT 43644 (approximately $1,450 Medicare physician fee). When the bypass includes a small intestine reconstruction for super-obesity or revision, use 43645 (approximately $1,650). Open gastric bypass uses 43846 (short limb, approximately $1,400) or 43847 (long limb with small bowel reconstruction, approximately $1,600). The laparoscopic codes reimburse slightly higher than open codes because the relative value units account for the technical complexity of the laparoscopic approach.
Most commercial payers reimburse gastric bypass at 150% to 250% of Medicare rates, placing total surgeon reimbursement between $2,100 and $3,600 per case. Facility fees are separate and substantially higher, but the surgeon professional component alone justifies meticulous coding to capture the correct procedure.
Sleeve Gastrectomy (43775)
Laparoscopic sleeve gastrectomy uses CPT 43775 (approximately $1,200 Medicare physician fee). This has become the most commonly performed bariatric procedure, accounting for roughly 60% of bariatric cases nationally. The code covers the entire sleeve creation including staple line reinforcement and leak testing. There is no separate open sleeve gastrectomy code; open conversion uses the unlisted code 43659 with a detailed operative report.
Sleeve gastrectomy reimbursement from commercial payers typically ranges from $1,800 to $3,000 for the surgeon professional fee. Some payers bundle the upper GI swallow study performed on postoperative day one into the global surgical period, while others allow separate billing. Check payer-specific policies before billing the swallow study separately.
Adjustable Gastric Banding (43770, 43771, 43772, 43773)
Laparoscopic adjustable gastric band placement uses CPT 43770 (approximately $1,050 Medicare physician fee). Related codes include 43771 (revision of band, approximately $800), 43772 (band and port removal, approximately $750), and 43773 (replacement of subcutaneous port, approximately $350). Band adjustments (fills) in the office use 43771 with the appropriate office E/M code.
Gastric banding has declined significantly in volume over the past decade, now representing fewer than 1% of bariatric procedures. However, band removal and conversion to sleeve or bypass remain common. When converting a band to a sleeve, bill both 43772 (removal) and 43775 (sleeve), using modifier 51 on the secondary procedure. Some payers bundle the removal into the conversion; appeal with the operative report showing two distinct procedures.
Revisional Bariatric Procedures
Revisional bariatric surgery (converting one procedure to another or revising a failed primary procedure) uses the primary procedure code for the new anatomy being created. A sleeve-to-bypass revision uses 43644 with documentation of the revisional nature. Add modifier 22 for increased procedural complexity due to adhesions and altered anatomy. Modifier 22 typically increases reimbursement by 20% to 30% but requires a detailed operative note explaining the additional work.
BMI Documentation Requirements
Every bariatric procedure requires documented BMI of 40 or greater, or BMI of 35 to 39.9 with at least one obesity-related comorbidity (type 2 diabetes, hypertension, obstructive sleep apnea, GERD). The BMI must be calculated from a measured height and weight in the medical record, not patient-reported. ICD-10 codes E66.01 (morbid obesity due to excess calories) or E66.2 (morbid obesity with alveolar hypoventilation) must be listed as the primary diagnosis. Secondary diagnosis codes for comorbidities (E11.x diabetes, I10 hypertension, G47.33 sleep apnea) support medical necessity.