Summary & Overview

HCPCS G9937: Diagnostic Colonoscopy

HCPCS Level II code G9937 designates a diagnostic colonoscopy — an endoscopic procedure used to inspect the colon for diagnostic purposes. This code is nationally relevant because colonoscopy is a common procedure for evaluating gastrointestinal symptoms, guiding diagnostic decision-making, and determining need for therapeutic intervention. Accurate coding affects claim routing, facility billing, and national utilization statistics.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of how the code is used in clinical and billing workflows, benchmarks for utilization and payment where available, and any recent policy or coverage considerations affecting diagnostic colonoscopy services. The publication also summarizes typical sites of service and the clinical context in which G9937 is applied.

This summary provides a national perspective useful for billing staff, revenue cycle leaders, and policy analysts seeking concise context on G9937, including operational implications for ambulatory surgical centers and hospital outpatient departments. Data not available in the input will be noted where applicable in detailed sections.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareG9937HCPCS Level IIdiagnostic colonoscopyendoscopyambulatory surgeryhospital outpatientgastroenterologyprocedure coding

Billing Code Overview

HCPCS Level II code G9937 represents diagnostic colonoscopy. This service involves endoscopic examination of the colon to evaluate gastrointestinal signs or symptoms and to establish a diagnosis.

Service type: Diagnostic endoscopic procedure

Typical site of service: Ambulatory surgical center or hospital outpatient department, depending on clinical setting and facility capabilities.

Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A 62-year-old patient presents to the gastroenterology clinic with a 3-month history of intermittent rectal bleeding and a change in bowel habits. The primary care physician refers the patient for a diagnostic colonoscopy to evaluate for colorectal neoplasia, inflammatory bowel disease, or other mucosal lesions. On the day of service the patient arrives fasting at an ambulatory endoscopy center. Pre-procedure verification includes informed consent, review of anticoagulant therapy, and bowel preparation adequacy. The procedure is performed by a gastroenterologist using conscious sedation administered by an anesthesia professional (or monitored anesthesia care if indicated). The colonoscope is advanced to the cecum, mucosa is inspected, and targeted biopsies are obtained for histopathology when suspicious lesions are identified. Specimens are submitted to the pathology lab; findings and follow-up recommendations are documented in the operative report and communicated to the referring provider.

Coding Specifications

Modifier	Description	When to Use
`22`	Increased procedural services	Use when work required is substantially greater than typical diagnostic colonoscopy due to complexity (extensive adhesiolysis, difficult scope advancement).
`23`	Unusual anesthesia	Use when general anesthesia is required for diagnostic colonoscopy due to patient condition (e.g., severe anxiety, inability to tolerate sedation).
`52`	Reduced services	Use when the colonoscopy is started but discontinued for documented clinical reasons and not completed to the cecum.
`53`	Discontinued procedure	Use when the procedure is aborted prior to induction of deep sedation or anesthesia for patient safety reasons.
`54`	Surgical care only	Use when the endoscopist performs the diagnostic colonoscopy but post-op care is billed by another practitioner.
`55`	Postoperative care only	Use when the endoscopist bills only post-procedure global period services separate from the diagnostic procedure billing.
`56`	Preoperative care only	Use when the practitioner bills only pre-procedure evaluation services and not the diagnostic colonoscopy itself.
`62`	Two surgeons	Use when two qualified physicians work together as primary surgeons during a complex endoscopic procedure requiring dual expertise.
`AS`	Ambulatory surgical center (facility)	Use to indicate the procedure was performed in an ambulatory surgical center.
`CO`	Left in input list (CO historically payer-specific)	Use per payer rules when coordination of benefits or specific payer-required modifier applies; verify payer-specific guidance.

Taxonomy Code	Specialty	Notes
`207VG0400X`	Gastroenterology	Primary specialty performing diagnostic colonoscopy.
`207L00000X`	General Surgery	Surgeons who perform diagnostic and therapeutic colonoscopy in operative settings.
`208D00000X`	Family Medicine	May perform screening or diagnostic colonoscopy in some settings with appropriate credentialing.
`207P00000X`	Colon & Rectal Surgery	Specialists performing complex colonoscopic procedures and surgical follow-up.
`2084P0800X`	Anesthesiology	Provides sedation or monitored anesthesia care during the procedure.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`K57.30`	Diverticulosis of large intestine without perforation or abscess	Diverticular disease can cause bleeding or change in bowel habit prompting diagnostic colonoscopy.
`K92.1`	Melena	GI bleeding symptom that commonly leads to colonoscopic evaluation to locate lower GI sources.
`K62.5`	Hemorrhage of anus and rectum	Presents with rectal bleeding; colonoscopy used to evaluate anorectal and colonic causes.
`R19.4`	Change in bowel habit	Non-specific symptom warranting colonoscopic evaluation for inflammatory or neoplastic causes.
`Z12.11`	Encounter for screening for malignant neoplasm of colon	Screening context that may convert to diagnostic colonoscopy if symptoms or positive screening tests are present.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`45378`	Colonoscopy, flexible, proximal to splenic flexure; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)	Primary CPT for diagnostic colonoscopy performed by endoscopist; commonly billed when procedural documentation meets CPT requirements.
`45380`	Colonoscopy, flexible, proximal to splenic flexure; with biopsy, single or multiple	Billed when targeted mucosal biopsies are obtained during diagnostic colonoscopy.
`45385`	Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by snare technique	Billed when a diagnostic colonoscopy proceeds to therapeutic polypectomy during the same session.
`99152`	Moderate sedation services provided by the same physician or other qualified health care professional performing the procedure, initial 15 minutes	Billed when moderate sedation is provided by the endoscopist or their team during colonoscopy when applicable.
`00810`	Anesthesia for lower intestinal endoscopic procedures, endoscope introduced distal to duodenum	Billed when anesthesia services (e.g., general anesthesia or MAC) are provided for the diagnostic colonoscopy.