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Top 4 Challenges in Anesthesia Coding for Medical Billing and Coding Leaders

Medical Billing and Coding service leaders often face major challenges with respect to compliance and documentation integrity. This task is more daunting for anesthesia coders because, unlike all physicians, anesthesiologists do not get paid based on the fee-for-service model but rather on start-up units, time units, modifier units, and any other additional procedure. This is quite a complex calculation to an extent where Medicare uses a National Anesthesia Conversion Factor to ease the calculation of reimbursements. The formula for calculating the reimbursement is (Start/base units + time units + modifier units) X conversion factor = $.

Quick fact – There are other types of anesthesiologists who can also administer anesthesia including certified registered nurse anesthetists (CRNAs), anesthesiologist assistants (AAs), and dental anesthesiologists. Did you know that an anesthesiologist can supervise up to 4 CRNAs concurrently?

A huge chunk of anesthesia medical billing and coding services is depending on accurate documentation and this documentation involves a lot of intricacies as there are multiple phases involved in it, majorly consisting of three parts, 1. Pre anesthesia evaluation, 2. Intraoperative/procedural anesthesia (a time-based record), and 3. Post anaesthesia evaluation. There are also challenges other than documentation when it comes to anesthesia coding.

Common Challenges in anesthesia medical billing and coding

  1. Mapping the surgery code – Unlike other specialties, in anesthesia, we need to first determine the CPT code for the surgery that was performed and map the surgery CPT with anesthesia CPT /ASA codes. This mapping is not an easy one-is-to-one concept and requires an anesthesia expert coder to work on it.
  2. Timekeeping – As already established before, anesthesia reimbursement is a time-based calculation. Time units are usually considered as 1 unit = 15 mins of anesthesia administration. Again, this becomes more complex for medical billing and coding leaders when multiple anesthesiologists and CRNAs work on single/multiple cases. Calculation of the time to the second becomes inevitable.
  3. Medical Direction vs Medical Supervision – Medical Direction occurs when an anesthesiologist is concurrently involved in up to four anesthesia procedures with a CRNA or an AA. According to the guidelines from the Centers for Medicare and Medicaid Services (CMS), there are 7 factors to be adhered to for it to be considered as medical direction,
  • Perform a pre-anesthetic examination and evaluation
  • Prescribe the anesthesia plan.
  • Personally participate in the most demanding procedures in the anesthesia plan, including, if applicable, induction and emergence.
  • Ensure that any procedures in the anesthesia plan that he or she does not perform are performed by a qualified individual.
  • Monitor the course of anesthesia administration at frequent intervals.
  • Remain physically present and available for immediate diagnosis and treatment of emergencies.
  • Provide indicated post-anesthesia care.

When an anesthesiologist cannot adhere to any of the said guidelines for the medical direction it is considered medical supervision. The HCPCS modifier for this is ‘AD – medical supervision by a physician: more than four concurrent anesthesia procedures’ which is used for the CPT codes 00100 through 01999. With respect to the medical billing and coding the payment for Medical supervision is based on three base units per procedure with an additional unit of time if the physician documents their presence at induction. The unit’s field must always be “1” when this modifier is used. Like Medical Direction there are set guidelines for medical supervision as well,

  • The anesthesiologist is involved in furnishing more than four procedures concurrently
  • The anesthesiologist is performing other services while directing the concurrent procedures. There are several exceptions to this requirement:
    • Addressing an emergency of short duration in the immediate area
    • Administering an epidural or caudal anesthetic to ease labor pain
    • Periodic (rather than continuous) monitoring of an obstetrical patient
    • Receiving patients entering the operating suite for the next surgery
    • Checking or discharging patients in the recovery room
    • Handling scheduling matters
  • These exceptions do not apply if the physician:
    • Leaves the operating suite for other than short durations
    • Devotes extensive time to an emergency case
    • Is otherwise not available to respond to the immediate needs of the surgical patient
  1. Modifying units – Changing health condition of the patient and emergencies are considered modifying units in anesthesia. For medical billing and coding purposes when multiple modifiers are used, operating modifiers are listed first followed by pricing modifiers.




Monitored anesthesia care (MAC) services (can be billed by a qualified non-physician anesthetist or physician)


Deep complex complicated, or markedly invasive surgical procedures


Appended with an anesthesia code to indicate that the patient has a history of a severe cardiopulmonary condition


A normal healthy patient


A patient with mild systemic disease


A patient with severe systemic disease


A Patient with severe systemic disease that is a constant threat to life


A moribund patient who is not expected to survive without the operation


A declared brain-dead patient whose organs are being removed for donor purposes




Anesthesia services personally performed by the anesthesiologist


Supervision, more than four procedures


Medical direction of two, three, or four concurrent anesthesia procedures


Qualified non-physician anesthetist with medical direction by a physician


Medical direction of one CRNA/AA by an anesthesiologist


Certified registered nurse anesthetist (CRNA) without medical direction by a physician

Anesthesia Coding with Codessence

Codessence our CAC coding platform has a separate anesthesia tool inbuilt that can automatically calculate the base unit, time unit, and the modifying unit and code to the highest level of compliance and accuracy. It can also handle the most complex concurrency situation & advise you with an appropriate modifier which no other anesthesia coding tool is capable of. Curious to see how the tool works? You can directly schedule a demo of codessence here