Summary & Overview
CPT 45399: Unlisted Procedure on Colon
CPT code 45399 designates an unlisted procedure on the colon and is used when no specific CPT code accurately describes the performed colon procedure. Nationally, unlisted procedure codes like 45399 matter because they require supplemental documentation for claims adjudication and can affect payment consistency, utilization tracking, and clinical reporting. Payers commonly involved in processing claims for this code include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
This publication provides a concise national overview of CPT code 45399: what the code represents, the typical clinical and site-of-service contexts where it is used, and the administrative considerations that commonly accompany unlisted procedure reporting. Readers will find guidance on the documentation expectations associated with unlisted colon procedures, an outline of common payer engagement for claim review, and discussion of where 45399 fits in clinical coding workflows. The report highlights benchmarking and policy-related themes relevant to payers and providers, and it identifies where additional clinical detail is typically required to support medical necessity and payment decisions. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 45399 is an unlisted procedure code used to report a procedure on the colon for which there is no specific CPT code. It captures unique or uncommon colon procedures that lack a designated code.
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Service type: Procedure on the colon
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Typical site of service: Hospital outpatient department, ambulatory surgery center, or inpatient operating room depending on clinical context and procedure complexity
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Clinical & Coding Specifications
Clinical Context
A typical patient is a 58-year-old male presenting with persistent abdominal pain, altered bowel habits, and unexplained rectal bleeding. After colonoscopy and standard endoscopic interventions, the endoscopist encounters an unusual or complex colon procedure not described by an existing CPT code—for example, an extensive endoscopic submucosal dissection of a large nonpolypoid lesion, a novel endoscopic full-thickness resection technique, or an unlisted combined open and endoscopic procedure on the colon. The clinical workflow begins with pre-procedure evaluation (history, medication reconciliation, informed consent), diagnostic colonoscopy with localization and documentation of the lesion, performance of the atypical therapeutic procedure, intra-procedural anesthesia management, specimen handling for pathology, and immediate post-procedure recovery and discharge instructions. Documentation must detail the indication, findings, step-by-step technique, duration, personnel, complexity, complications (if any), and rationale for using an unlisted code 45399 because no specific CPT code describes the service performed.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services | When the procedure required substantially greater work, time, or technical difficulty than typically reported for related coded services. |