Summary & Overview

HCPCS G4018: Obstetrics/Gynecology MIPS Specialty Set

HCPCS Level II code G4018 identifies the obstetrics/gynecology MIPS specialty set, a collection of quality and performance measures used for Medicare MIPS reporting for clinicians in obstetrics and gynecology. Nationally, this code matters because it ties specialty-specific quality reporting to payment adjustments and public performance visibility under federal value-based programs. Use of this code signals that a clinician or group is reporting the designated obstetrics/gynecology measures rather than individual encounter procedures.

Key payers in the national context include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. These payers participate in quality and performance programs that intersect with MIPS reporting expectations or maintain aligned quality initiatives, influencing how obstetrics/gynecology practices prioritize measure capture and documentation.

Readers will learn what G4018 represents, the clinical and administrative context for its use, and what to expect from documentation and encounter settings tied to obstetrics/gynecology quality reporting. The publication summarizes benchmarks, policy implications for national quality programs, and clinical context for outpatient obstetrics and gynecology services. Data not available in the input for specific payor policies, detailed measure lists, associated taxonomies, and ICD-10 pairings are noted where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareG4018HCPCS Level IIObstetricsGynecologyMIPSQuality ReportingOutpatient CarePerformance MeasuresValue-based Care

Billing Code Overview

HCPCS Level II code G4018 denotes the Obstetrics/gynecology MIPS specialty set. This code identifies a specialty-specific quality and performance measure set used within the Medicare Merit-based Incentive Payment System (MIPS) framework to represent performance reporting for clinicians practicing in obstetrics and gynecology.

Service Type: Quality measure reporting for obstetrics/gynecology clinicians

Typical Site of Service: Outpatient ambulatory clinics and physician offices providing obstetrics and gynecology care

Clinical & Coding Specifications

Clinical Context

A typical patient is a 28–36-year-old woman presenting for obstetrics/gynecology care participating in MIPS (Merit-based Incentive Payment System) quality reporting. Clinical workflow: during a prenatal or well-woman visit the clinician documents preventive care, screening results, counseling, and pregnancy management tasks in the electronic health record. The practice maps encounters to the G4018 specialty set for reporting to Medicare and internal quality programs. Medical assistants room the patient, obtain vitals, and update problem lists and medication reconciliations. The clinician performs focused history and exam, orders indicated tests (for example, prenatal labs, sexually transmitted infection screening, or cervical cytology), and documents counseling and shared decision-making. Coding staff assign G4018 to indicate the obstetrics/gynecology MIPS specialty set was used for quality reporting for that encounter. Typical site of service is an outpatient clinic or obstetrics/gynecology ambulatory practice. Common patient scenarios include prenatal visits, postpartum visits, annual gynecologic preventive visits, and problem-focused visits for gynecologic conditions when MIPS reporting is active for the provider or group.

Coding Specifications

Modifier	Description	When to Use
`22`	Increased procedural services	Use when work required is substantially greater than typical for the reported service (document increased work).
`52`	Reduced services	Use when a service is partially reduced or not completed at the usual level.
`53`	Discontinued procedure	Use when procedure is started but stopped due to extenuating circumstances.
`54`	Surgical care only	Use when the surgeon provides only the surgical portion and another physician provides pre/postoperative care.
`55`	Postoperative management only	Use when a physician provides only postoperative care.
`62`	Two surgeons	Use when two surgeons work together as primary surgeons performing distinct portions of the procedure.
`AS`	Ambulatory surgical center facility	Use to indicate the service was furnished in an ASC setting.
`QK`	Medical direction of two, three, or four assistants	Use when physician directs multiple qualified assistants during the procedure.
`QX`	Qualified nonphysician assistant	Use when a qualified nonphysician assistant performs the assistant-at-surgery role under proper supervision.
`QY`	Medicare-approved resident teaching physician	Use when a teaching physician performs primary procedure with a resident participating under approved conditions.
`FX`	Clinical trial, non-covered service secondary to trial	Use to indicate a service is related to a clinical trial and not separately covered.
`FY`	Discontinued clinical trial procedure	Use when an item or service in a clinical trial is discontinued.
`CO`	Routine clinical trial non-covered service	Use for items/services that are not covered when provided for clinical trial participants.
`CQ`	Service furnished under a watchful waiting or care plan related to research	Use when services relate to research monitoring per program guidance.

Taxonomy Code	Specialty	Notes
`207VG0400X`	Obstetrics & Gynecology	Core specialty reporting `G4018` MIPS set.
`207V00000X`	Obstetrics	Providers primarily managing prenatal care and deliveries.
`207VH0000X`	Gynecology	Providers focused on non-obstetric gynecologic care and preventive services.
`163W00000X`	Family Medicine	Commonly provides prenatal and well-woman care and participates in MIPS.
`208D00000X`	Internal Medicine	May provide women's preventive care and participate in MIPS quality reporting.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`Z34.90`	Encounter for supervision of normal pregnancy, unspecified, unspecified trimester	Common diagnosis for routine prenatal visits included in obstetrics MIPS reporting.
`Z34.80`	Encounter for supervision of pregnancy, multiple gestation	Used when supervising prenatal care for multiple gestation pregnancies contributing to obstetric quality metrics.
`Z30.09`	Encounter for other general counseling and advice on contraception	Used for family planning and preventive counseling visits in gynecology MIPS measures.
`Z30.431`	Encounter for initial prescription of intrauterine contraceptive	Applied when IUD initiation occurs and is captured in preventive service reporting.
`Z01.411`	Encounter for gynecological examination (general) (with cervical smear)	Routine well-woman visits with cervical cytology are part of gynecology quality measures.
`N76.0`	Acute vaginitis	Common problem-focused gynecologic diagnosis encountered during visits and tracked in quality/improvement activities.
`O09.90`	Supervision of high-risk pregnancy, unspecified, unspecified trimester	Used for high-risk prenatal care encounters that are included in obstetrics reporting.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`59400`	Obstetrical care including antepartum care, vaginal delivery (with or without episiotomy and/or forceps) and postpartum care	Performed by obstetric providers who also report MIPS obstetrics/gynecology measures; relevant for prenatal and delivery episode reporting.
`99213`	Office or other outpatient visit for the evaluation and management of an established patient, typically 15 minutes	Common E/M visit code used during prenatal or gynecology visits that feed into MIPS quality reporting in the `G4018` specialty set.
`99214`	Office or other outpatient visit for the evaluation and management of an established patient, typically 25 minutes	Used for more complex prenatal or gynecologic visits contributing to MIPS performance data.
`58300`	Insertion of intrauterine device (IUD)	A common gynecologic procedure that may occur during ambulatory visits tracked in MIPS measures.
`88142`	Cytopathology, cervical or vaginal (screening) — requiring interpretation by physician	Cervical cytology and related screening tests are key components of preventive care measures within the obstetrics/gynecology MIPS set.
`87070`	Culture, bacterial; any other source, except urine, aerobic bacterial isolate	Microbiology testing such as STI screenings ordered during visits are relevant to quality reporting in the `G4018` set.