S3645 — Hiv-1 antibody testing of oral mucosal transudate
S3645 is a HCPCS Level II code for hiv-1 antibody testing of oral mucosal transudate. It belongs to the Temporary National Codes (Non-Medicare) section. Medicare does not pay it — see the coverage note below before you bill it.
Medicare coverage: Not payable by Medicare
Medicare does not pay this code. It may still be valid for another payer, but a Medicare claim carrying it will not be reimbursed.
From the coverage field of the CMS Alpha-Numeric HCPCS File, release 2026Q3-Jul. This states Medicare’s position on the code, not on your particular claim.
Physician fee schedule statusI
Not valid for Medicare purposes. Medicare uses another code.
Global period: XXX
Want the dollar amount for your locality? The fee calculator applies your GPCI and the current conversion factor.
The CMS record for S3645
- Long descriptor
- Hiv-1 antibody testing of oral mucosal transudate
- Short descriptor
- Hiv-1 antibody testing of or
- Added
- January 1, 2000
- BETOS
- Z2
- Pricing indicator
- 00 — Not priced by Part B
The official wording. This is what the code means.
CMS's 28-character form, which is what shows up on a remittance advice.
When CMS introduced the code.
Berenson-Eggers Type of Service — CMS's own analytic grouping.
Service not separately priced by Part B — not covered, bundled into another service, or used by Part A only.
Codes adjacent to S3645
HCPCS has no hierarchy — related items simply sit next to each other in the numbering. If S3645 is not quite right, the correct code is very often within a few positions of it.
- S2411Fetoscopic laser therapy for treatment of twin-to-twin transfusion syndrome
- S2900Surgical techniques requiring use of robotic surgical system (list separately in addition to code for primary procedure)
- S3000Diabetic indicator; retinal eye exam, dilated, bilateral
- S3005Performance measurement, evaluation of patient self assessment, depression
- S3600Stat laboratory request (situations other than s3601)
- S3601Emergency stat laboratory charge for patient who is homebound or residing in a nursing facility
- S3620Newborn metabolic screening panel, includes test kit, postage and the laboratory tests specified by the state for inclusion in this panel (e.g., galactose; hemoglobin, electrophoresis; hydroxyprogesterone, 17-d; phenylalanine (pku); and thyroxine, total)
- S3630Eosinophil count, blood, direct
- S3650Saliva test, hormone level; during menopause
- S3652Saliva test, hormone level; to assess preterm labor risk
- S3655Antisperm antibodies test (immunobead)
- S3708Gastrointestinal fat absorption study
- S3721Prostate cancer antigen 3 (pca3) testingterminated
- S3722Dose optimization by area under the curve (auc) analysis, for infusional 5-fluorouracil
- S3800Genetic testing for amyotrophic lateral sclerosis (als)
- S3840Dna analysis for germline mutations of the ret proto-oncogene for susceptibility to multiple endocrine neoplasia type 2
Questions about S3645
What is HCPCS code S3645?
S3645 is a HCPCS Level II code for hiv-1 antibody testing of oral mucosal transudate. It sits in the Temporary National Codes (Non-Medicare) section.
Does Medicare cover S3645?
The CMS HCPCS file marks S3645 as "Not payable by Medicare". Medicare does not pay this code. It may still be valid for another payer, but a Medicare claim carrying it will not be reimbursed.
How is S3645 paid under the physician fee schedule?
S3645 carries PFS status code I. Not valid for Medicare purposes. Medicare uses another code.