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CPT 45378: Colonoscopy with Brushings or Washings for Diagnostic Analysis
CPT code 45378 denotes a diagnostic colonoscopy in which the provider inspects the colon and rectum using a colonoscope and collects mucosal samples by brushings or saline washings for laboratory analysis. This code captures procedures focused on visual assessment with targeted specimen retrieval rather than polypectomy or advanced therapeutic maneuvers. Nationally, colonoscopy with sampling remains a key tool for diagnosing mucosal disease, evaluating abnormal screening tests, and guiding management of suspected neoplasia or inflammatory conditions.
Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, United Healthcare, and Medicare. Readers will find a concise clinical description of the service, typical sites of care, common clinical indications, and related CPT codes that delineate diagnostic sampling from biopsy, polypectomy, and other therapeutic colonoscopy services. The publication also summarizes common procedural modifiers and relevant ICD-10 diagnoses associated with this service line. Policy- and billing-focused readers will gain clarity on code intent and how 45378 relates to adjacent codes used for removal, biopsy, hemostasis, and other interventions. Operational leaders can use the information to align coding practices with clinical documentation and payer billing expectations.
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Billing Code Overview
CPT code 45378 describes a diagnostic colonoscopy with mucosal sampling. The procedure uses a colonoscope, a flexible tube with a camera, to examine the colon and rectum; when abnormal mucosa or tissue is identified, the provider obtains specimens by brushing the mucosa or by irrigating the area with warm saline and aspirating washings. Specimens are sent to the laboratory for diagnostic analysis.
Service type: Diagnostic endoscopic procedure with specimen collection
Typical site of service: Ambulatory surgery center or hospital outpatient department, with some procedures performed in endoscopy suites or facility-based outpatient clinics.
National Reimbursement Benchmarks
Medicare's mean rate for CPT 45378 sits at $293.80, notably below BUCA's average commercial mean of $706.50 — a gap of $412.70 that highlights a substantial difference between federal reimbursement and this commercial benchmark. Blue Cross Blue Shield ($936.40 mean), Cigna ($435.10 mean), UnitedHealth Group ($500.70 mean), and Aetna ($264.00 mean) fall across the spectrum between those two anchors, reinforcing a wide commercial pricing band around the Medicare baseline.
Dispersion measured as the interquartile difference (P75 minus P25) is widest for Blue Cross Blue Shield at $740.40 and for Aetna at $242.60, with BUCA's IQR equal to $516.40. The tightest spread is Cigna at $313.50, followed by UnitedHealth Group at $316.90 and Medicare at $192.00, indicating that some payers cluster reimbursements more closely while others exhibit substantial variation.