Summary & Overview
CPT 43845: Gastric Bypass Bariatric Surgery
CPT code 43845 identifies a gastric bypass bariatric surgery that reduces stomach volume and bypasses a significant portion of the small intestine to limit absorption and treat morbid obesity. Nationally, this code represents a high-impact surgical intervention used in the management of severe obesity, with implications for surgical capacity, payer coverage policies, and post‑operative care pathways. Key payers commonly involved in coverage and payment decisions include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
Readers will find a concise overview of the clinical intent and typical settings for CPT code 43845, a national framing of payer coverage considerations, and what to expect in benchmarking and policy contexts. The publication covers reimbursement benchmark summaries, common billing and coding considerations, and relevant clinical context for patient selection and perioperative care. It also highlights typical sites of service and the service type for stakeholders involved in surgical program planning, utilization review, and billing compliance. Data not available in the input is noted where specific payer rates, taxonomies, ICD‑10 pairings, and related codes would normally appear.
Billing Code Overview
CPT code 43845 describes a surgical bariatric procedure in which the provider reduces the size of the stomach and creates a bypass of a large portion of the small intestine to limit nutrient absorption and treat morbid obesity. This operation is a form of gastric bypass surgery used to achieve significant and sustained weight loss for patients with severe obesity.
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Service type: Surgical bariatric procedure
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Typical site of service: Inpatient hospital or ambulatory surgical center depending on clinical indication and perioperative needs
Clinical & Coding Specifications
Clinical Context
A 42-year-old patient with class III obesity (BMI ≥40 kg/m2) and obesity-related comorbidities such as type 2 diabetes mellitus and obstructive sleep apnea presents for elective bariatric surgery. After comprehensive multidisciplinary evaluation including nutrition, behavioral health, and preoperative medical optimization, the patient is scheduled for a Roux-en-Y gastric bypass. The procedure involves creation of a small gastric pouch and construction of a gastrojejunal anastomosis with bypass of a portion of the small intestine to restrict intake and reduce nutrient absorption. Typical workflow includes preoperative clearance, anesthesia evaluation, surgical consent, laparoscopic or open operative approach, intraoperative stapling and anastomosis, immediate postoperative recovery in PACU, inpatient monitoring for 24–72 hours, initiation of staged diet progression, and outpatient follow-up with the bariatric team for nutrition and complication surveillance. Common perioperative considerations include venous thromboembolism prophylaxis, glycemic control, infection prevention, and management of potential anastomotic leak or obstruction.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | No modifier | Standard reporting when no modifier applies |
22 | Increased procedural services | Use when work or complexity substantially greater than usual for the procedure |
52 | Reduced services | Use when the procedure is partially reduced or not completed as described |
53 | Discontinued procedure | Use when procedure is terminated due to extenuating circumstances prior to completion |
62 | Two surgeons | Use when two surgeons work together as primary surgeons performing distinct portions |
63 | Procedure performed on infants less than 4 kg | Rarely used; apply when patient meets weight criteria for neonatal modifier applicability |
66 | Surgical team concept | Use when a surgical team (multiple surgeons) performs the procedure under a documented team model |
78 | Unplanned return to the operating room for a related procedure following initial surgery | Use for immediate postoperative return to OR for complications related to the original procedure |
80 | Assistant surgeon | Use when an assistant surgeon is documented and eligible for payment |
81 | Minimum assistant surgeon | Use when minimal assistance is provided and documented |
82 | Assistant surgeon (when a qualified resident is not available) | Use when assistant surgeon services are needed but a resident is not available |
AS | Physician assistant, nurse practitioner, or clinical nurse specialist service | Use when an eligible non-physician practitioner performs part of the procedure per local payer rules |
QX | CRNA service: CRNA with physician direction | Use when a certified registered nurse anesthetist provides anesthesia with physician direction |
QY | Medical direction of two, three, or four concurrent anesthesia procedures | Use when physician directs multiple concurrent anesthesia services for the case |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 208600000X | General Surgery | Most bariatric Roux-en-Y gastric bypass procedures are performed by board-certified general surgeons with bariatric fellowship training |
| 208000000X | Colon and Rectal Surgery | Some colorectal surgeons with advanced minimally invasive skills participate in complex revisional or combined procedures |
| 208800000X | Thoracic Surgery | Occasionally involved for complex revisional cases with adjacent thoracic involvement |
| 208200000X | Gastroenterology | Gastroenterologists do not perform the surgical bypass but provide pre/postoperative endoscopic assessment and management |
| 364A00000X | Anesthesiology | Anesthesiologists and CRNAs provide perioperative anesthesia care for bariatric patients |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
E66.01 | Morbid (severe) obesity due to excess calories | Primary indication for Roux-en-Y gastric bypass in patients with BMI ≥40 kg/m2 or BMI ≥35 kg/m2 with comorbidities |
E66.9 | Obesity, unspecified | Often used when obesity severity is documented but specific subclass not recorded; supports bariatric surgery evaluation |
E11.9 | Type 2 diabetes mellitus without complications | Common obesity-related comorbidity that may improve following gastric bypass |
I10 | Essential (primary) hypertension | Frequently coexists with obesity and is a reason for metabolic improvement monitoring after surgery |
G47.33 | Obstructive sleep apnea (adult) (pediatric) | Common comorbidity that affects perioperative risk and may improve after weight loss |
K21.9 | Gastro-esophageal reflux disease without esophagitis | Preoperative assessment is important because RYGB can improve reflux symptoms compared with restrictive procedures |
E78.5 | Hyperlipidemia, unspecified | Metabolic comorbidity often present in bariatric candidates and monitored perioperatively |
Z68.41 | Body mass index (BMI) 40.0-44.9, adult | Documentation of BMI category is required to support medical necessity for bariatric surgery |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
43644 | Laparoscopy, surgical, gastric restrictive procedure; longitudinal gastrectomy (sleeve gastrectomy) | Common alternative primary bariatric operation; may be performed instead of or prior to conversion to gastric bypass |
43770 | Laparoscopy, surgical, revision of gastric bypass; restrictive component, with revision of stoma and/or pouch | Performed when revision of a prior Roux-en-Y gastric bypass is required for complications or weight regain |
43280 | Endoscopy, flexible; esophagogastroduodenoscopy, diagnostic, with or without collection of specimen by brushing or washing (separate procedure) | Frequently performed preoperatively for evaluation of gastroesophageal disease and postoperatively for evaluation of symptoms or anastomotic complications |
47562 | Laparoscopy, surgical; cholecystectomy | Common simultaneous or staged procedure because obese patients frequently have symptomatic cholelithiasis; often performed during the same hospitalization or prior to bariatric surgery |
43775 | Laparoscopy, surgical, revision of gastric restrictive procedure to bypass component (e.g., conversion to Roux-en-Y) | Used when converting restrictive procedures to a bypass for inadequate weight loss or complications |