CASCC common mistakes
CASCC · Understand the traps and how to avoid them.
Assigning a single integumentary excision code based only on the lesion diameter without measuring the actual excised diameter including margins, and without distinguishing benign (diameter-only) from malignant (diameter plus margin) rules.
Candidates memorize code ranges by size band and skip the two-step measurement (lesion plus margins for malignant lesions), so the size band chosen is systematically too small.
What to do instead
For every excision, write out three numbers before selecting a code: lesion diameter, margin on each side, and total excised diameter; then apply the benign vs malignant rule and confirm the code's size band contains the total.
Reporting lesion destruction (e.g., 17000-17250) when the op note describes a full-thickness excision with layered closure, or vice versa.
Candidates pattern-match on the word 'removal' in the operative note without reading the technique paragraph that specifies shaving, destruction, or excision with suture.
What to do instead
Classify the technique first: destruction (no specimen), shave, or excision (specimen sent). Only then pick the code family; if a specimen went to pathology, destruction codes are wrong.
Bundling a wound repair code with an excision on the same site, or separately reporting a layered closure that the excision code already includes, and mis-adding repair lengths across multiple wounds.
Candidates treat every documented closure as separately billable and add all wound lengths into one repair code instead of grouping by anatomic site and complexity.
What to do instead
Apply the integumentary bundle rules: simple repairs are included with excisions; for multiple wounds, group by site and by simple/intermediate/complex, sum lengths within each group, and report the most complex group first.
Using modifier 59 or X{EPSU} to force payment on a pair of codes that are actually integral to each other, rather than recognizing a true distinct service.
Candidates reach for 59 as a default unbundling tool instead of first checking NCCI edits and the code descriptors for a parent-child relationship.
What to do instead
Before any bypass modifier, verify the edit exists and articulate in one sentence why the service is distinct (different site, separate encounter, independent procedure). If that sentence cannot be written, do not append the modifier.
Selecting an anesthesia code by the surgical procedure name rather than by the anatomic site and the anesthesia section's own cross-reference, and omitting qualifying circumstances or physical status modifiers.
Candidates look up the surgeon's CPT code and assume the anesthesia code mirrors it; the anesthesia section is organized by body site and often cross-references a different code.
What to do instead
Locate the anesthesia code via the Anesthesia section index by site and procedure, confirm any cross-reference, then add the correct physical status modifier (P1-P6) and qualifying circumstance codes only when documented.
Billing evaluation and management services on the same day as a minor procedure without a documented, separately identifiable service, or missing the modifier that supports it.
Candidates see an office visit note and a procedure note and bill both, without checking that the E/M was significant and separately identifiable from the procedure's global package.
What to do instead
Confirm the note documents a distinct problem or workup unrelated to the procedure; if so, append modifier 25 to the E/M. If the visit was solely to decide on or perform the procedure, bill the procedure only.
Reporting radiology codes without matching the number of views, the modality, and whether contrast was used, and misapplying the professional/technical component split.
Candidates default to a generic 'X-ray, two views' code and ignore that the code family changes with view count and contrast, and that global vs component billing depends on who owns the equipment and interpretation.
What to do instead
Read the order and report for modality, view count, and contrast; select the code that matches all three. Then determine global (26+TC), professional only (26), or technical only (TC) based on the setting and who performed each part.
Assigning pathology or laboratory codes without distinguishing the specimen source, the method, and whether the service is a screening vs diagnostic test, and omitting the professional/technical split.
Candidates treat all lab codes as interchangeable by test name and overlook that method (e.g., quantitative vs qualitative) and specimen type drive code selection, and that screening vs diagnostic changes coverage.
What to do instead
For each specimen, record source, method, and clinical purpose (screening vs diagnostic) before coding; verify the code descriptor matches the method, and apply 26/TC consistently with who performed the service.
Coding medicine/ancillary services (injections, infusions, monitoring) by the drug name alone, ignoring the hierarchy rules for initial vs subsequent and the time-based add-on structure.
Candidates bill one code per drug administered and skip the hydration/initial/subsequent hierarchy and the time documentation required for add-on codes.
What to do instead
Build the infusion hierarchy first (hydration, then initial, then subsequent, then add-ons), document start/stop times, and report only the highest-level service per time period per the hierarchy.
Submitting ambulatory surgery center claims with mismatched CPT/HCPCS pairs, missing revenue codes, or incorrect place-of-service and modifier indicators that cause claim rejection or downcoding.
Candidates focus on the procedure code and neglect the facility-side data elements (revenue code, POS, payment indicator) that the ASC claim requires, so clean professional coding still yields denials.
What to do instead
Before submission, run a claim scrub checklist: CPT-to-HCPCS crosswalk, revenue code matches the service line, POS 24 for ASC, correct payment indicator, and NCCI edits cleared. Reconcile any denial against that checklist rather than resubmitting unchanged.