Coding accuracy depends heavily on specialty-specific knowledge — the same visit can be coded very differently in cardiology versus dermatology versus behavioral health. This guide summarizes the coding landmarks for the specialties that generate the most billing questions. Each section covers the CPT/HCPCS ranges you’ll use most and specialty-specific pitfalls.
Cardiology
Primary code range: 70000–79999 (diagnostic imaging) and 92920–93799 (cardiovascular procedures)
Cardiology coding combines E/M visits with high-value procedures like cardiac catheterizations, echocardiograms, and stress tests. Watch for bundling edits between diagnostic tests performed on the same day, and use modifier 26 (professional component) / TC (technical component) correctly when a physician only interprets a test performed elsewhere.
Read the full Cardiology billing guide →
Orthopedics
Primary code range: 20000–29999 (musculoskeletal system)
Orthopedic coding is procedure-heavy: fracture care, joint injections, and surgical scopes. Global surgical packages are a major pitfall — many post-op visits are already bundled into the surgery’s global period and shouldn’t be billed separately. Modifiers 58, 78, and 79 govern related procedures during that window.
Read the full Orthopedics billing guide →
Mental & Behavioral Health
Primary code range: 90785–90899 (psychiatry) and 96130–96139 (psych/neuropsych testing)
Time-based codes are central here — many psychotherapy codes (e.g., 90832, 90834, 90837) are chosen by session length, so accurate time documentation is essential. Add-on code 90785 for interactive complexity and correct use of telehealth modifiers (95, GT) are common problem areas.
Read the full Mental and Behavioral Health billing guide →
Dermatology
Primary code range: 10000–19999 (integumentary system)
Dermatology mixes E/M visits, biopsies, and destruction/excision procedures, often on the same visit. Correct use of modifier 25 (significant, separately identifiable E/M) is one of the most frequently audited issues in this specialty.
Read the full Dermatology billing guide →
Radiology
Primary code range: 70000–79999
Radiology billing separates the professional component (physician interpretation) from the technical component (equipment/staff), using modifiers 26 and TC. Bundling rules between related imaging studies are common denial triggers.
Read the full Radiology billing guide →
Anesthesia
Primary code range: 00100–01999, billed with time units rather than flat fees
Anesthesia uses a unique payment formula: base units (by procedure) plus time units, adjusted by modifiers like AA, QK, or QX depending on who administered the anesthesia and how it was medically directed.
Read the full Anesthesia billing guide →
OB/GYN
Primary code range: 58300–59899 (female genital system, maternity care)
Global maternity billing bundles routine antepartum care, delivery, and postpartum care into a single code — billing pieces separately outside that bundle is a common and costly mistake.
Read the full OB/GYN billing guide →
Physical & Occupational Therapy
Primary code range: 97110–97799
Therapy billing is time-based using 15-minute units under the “8-minute rule,” and often requires functional limitation reporting and therapy caps tracking depending on payer.
Read the full Physical and Occupational Therapy billing guide →
Emergency Medicine
Primary code range: 99281–99285 (ED E/M levels)
ED visit levels are chosen by medical decision-making complexity and are frequently audited; documentation must clearly support the level billed. Critical care time (99291/99292) has its own strict time-tracking requirements.
Read the full Emergency Medicine billing guide →
Family & Internal Medicine
Primary code range: 99202–99215 (office/outpatient E/M)
The 2021 E/M guideline overhaul shifted level selection to medical decision-making or total time — accurate, specific documentation of both is what supports the code chosen.
Read the full Family and Internal Medicine billing guide →
Urology
Primary code range: 50010–53899 (urinary system) and 54000–55899 (male genital system)
Urology billing spans office E/M, cystoscopy, and surgical procedures on the urinary and male genital systems. Modifier 50 (bilateral procedure) is common for paired-organ procedures, and ICD-10 codes in the N30–N53 range (cystitis, BPH, erectile dysfunction) frequently support medical necessity.
Read the full Urology billing guide →
Orofacial Pain / TMJ
Primary code range: CPT 21010–21499 (facial/TMJ) and imaging 70328–70332; dental codes D7899, D9210 for related dental services
Orofacial pain and TMJ disorders often straddle medical and dental billing — diagnostic imaging and injections may bill to medical using ICD-10 M26.6x (TMJ disorders) or G50 (trigeminal neuralgia), while appliance therapy may bill under dental CDT codes. Confirming which payer (medical vs. dental) covers a given service is a common pain point.
Read the full Orofacial Pain / TMJ billing guide →
Pediatrics
Primary code range: 99381–99395 (preventive medicine, new/established patient) and 90460–90474 (immunization administration)
Pediatric billing centers on well-child visits and vaccine administration, coded separately from the vaccine product itself (CPT 90xxx vaccine codes). ICD-10 Z00.129 (well child exam without abnormal findings) is used heavily, and correctly unbundling a sick visit from a same-day well visit (modifier 25) is a frequent issue.
Read the full Pediatrics billing guide →
Podiatry
Primary code range: 28001–28899 (foot and toe procedures)
Podiatry has unique routine foot care coverage rules — Medicare generally excludes routine care unless a qualifying systemic condition (e.g., diabetes) is documented, tracked using Q7/Q8/Q9 modifiers for at-risk foot findings. ICD-10 codes like E11.51 (diabetes with peripheral angiopathy) are often required to support medical necessity.
Read the full Podiatry billing guide →
Laboratory / Pathology
Primary code range: 80047–89398 (pathology and laboratory)
Lab billing depends heavily on medical necessity linkage between the ordering diagnosis and the test performed; missing or non-covered ICD-10 codes are a leading cause of lab denials. Modifier 91 (repeat clinical diagnostic lab test) and modifier 90 (reference lab) are common, and many payers require an Advance Beneficiary Notice (ABN) for tests likely to be denied as not medically necessary.
Read the full Laboratory / Pathology billing guide →
Dental
Primary code range: CDT codes D0100–D9999 (a separate code set from CPT); oral surgery may cross over to CPT 21xxx / 41xxx for medical billing
Dental services are billed using CDT (Current Dental Terminology) codes rather than CPT, typically to a separate dental plan. Certain oral surgery, trauma, or pathology procedures qualify for medical billing instead of (or in addition to) dental billing, which requires understanding both code sets and payer rules for which one applies.
Read the full Dental billing guide →
Nephrology
Primary code range: 90935–90940 (dialysis procedures) and 90951–90970 (ESRD-related services)
Nephrology billing includes routine office visits as well as recurring dialysis and End-Stage Renal Disease (ESRD) monthly capitation codes, which bundle a set number of visits per month. ICD-10 N18.x (chronic kidney disease stages 1–5) drives medical necessity, and correctly counting visits within an ESRD billing month is a common error.
Read the full Nephrology billing guide →
Allergy & Asthma
Primary code range: 95004–95199 (allergy testing and immunotherapy)
Allergy and asthma billing separates allergy testing, allergen immunotherapy (allergy shots), and E/M visits — modifier 25 is frequently needed when a significant, separately identifiable E/M service is billed alongside testing or injections on the same day. ICD-10 J45.x (asthma, by severity) and Z-codes for allergy status are common.
Read the full Allergy & Asthma billing guide →
Ambulatory Surgical Center (ASC)
Primary code range: Facility billing uses the same CPT/HCPCS codes as the physician claim, reported on a UB-04 with place of service 24
ASC billing is facility billing layered on top of the physician’s professional claim — the ASC bills its own facility fee for the procedure, supplies, and staff time, separate from the surgeon’s professional fee. ASC payment rates follow CMS’s ASC payment groups, and not every procedure approved for hospital outpatient settings is approved for the ASC setting.
New to coding? Start with our Medical Billing Process overview, then explore official code sets and lookup tools on our Free Resources page.
Read the full Ambulatory Surgical Center (ASC) billing guide →