The four codes
- 99100: anesthesia for a patient of extreme age, under one year or over seventy
- 99116: anesthesia complicated by total body hypothermia
- 99135: anesthesia complicated by controlled hypotension
- 99140: anesthesia complicated by emergency conditions
These are reported in addition to the main anesthesia code.
Who pays
Medicare bundles these and doesn't pay extra. Many commercial payers do add units. Your contracts decide.
Make sure they're captured
Patient age is easy to catch automatically. Emergency status and hypotension depend on documentation, so make sure your records say it clearly when it applies.
This article is general information, not billing, legal or tax advice. Payer rules change; always check current guidance.
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