Linking scans to preprocedure encounter codes is the key to compliant coding.
You already know that vascular duplex scans are a hot spot for errors. (See “80 Percent of Vascular Study Claims Are Wrong, Reveals NGS Review,” in this issue.)
Supporting medical necessity for the scan is a major factor in presenting a clean claim. From a coding perspective that means assigning the appropriate ICD-10-CM code, based on the documentation, that supports the procedure coded in the claim.
You also need to check whether the payer lists that ICD-10 code as a supporting diagnosis in an LCD for the service. (Remember, the diagnosis code you report must be supported by the documentation. Never choose a code just because you know it will get the claim through for payment.)
Example: NGS’s LCD L33627, “Non-Invasive Vascular Studies,” provides long lists of ICD-10 codes that will support medical necessity for specific CPT® codes. It also provides sequencing instructions.
For instance, for “Pre-surgical Conduit Mapping for Coronary Artery Bypass Graft Procedures (93930, 93931, 93965, 93970, and 93971),” NGS lists 40 codes in categories I20 to I25 that support medical necessity for the listed CPT® codes.
But the LCD also provides this instruction: “List ICD-10 code Z01.810 (Encounter for preprocedural cardiovascular examination) or Z01.818 (Encounter for other preprocedural examination) as the primary diagnosis. The secondary diagnoses should identify the reason for the study and/or findings.”
So if documentation shows performance of 93970 (Duplex scan of extremity veins including responses to compression and other maneuvers; complete bilateral study) to perform conduit mapping in a patient about to undergo coronary artery bypass graft (CABG) procedure for coronary atherosclerosis, your claim would show 93970 linked to primary code Z01.810 and secondary code I25.10 (Atherosclerotic heart disease of native coronary artery without angina pectoris).