Intraoperative Monitoring

Policy No: 101
Originally Created: 03/01/2011
Section: Surgery
Last Reviewed: 03/01/2024
Last Revised: 03/01/2024
Approved: 03/14/2024
Effective: 04/01/2024

This policy applies only to physicians, other qualified health care professionals and facilities.


Intraoperative monitoring (IOM)
Used to identify compromise to the central or peripheral nervous system, cardiac or vascular system, respiratory system, etc. The intent of the monitoring is to alert the surgeon in order that the surgical procedure may be altered to avoid permanent damage. Such impairments may be due to correctable factors such as a circulatory disturbance, excess compression from a retractor, bony structures or hematomas, or mechanical stretching.

Intraoperative monitoring can also:

  • Identify new systemic impairment
  • Identify separate nervous system structures, e.g., around or in a tumor
  • Demonstrate which tracts of nerves are still functional
  • Assist in reconstruction of cardiac structures
  • Aid in the identification and mapping of abnormal cardiac and brain foci

Intraoperative neurophysiological monitoring (IONM)
Subset of IOM used as adjunct for surgeries that pose risk to nervous system structures.

Train-of-Four (TOF) monitoring
Used to assess neuromuscular transmission when neuromuscular blocking agents (NMBAs) are given to block musculoskeletal activity.

Policy statement

IOM/IONM is accomplished by a certified technologist in continuous attendance in the operating room; who sets up the specialized monitoring equipment including any necessary connection to the patient, and then performs the intraoperative monitoring. Monitoring oversight must be provided by the appropriate supervising physician.

IOM/IONM charges billed by the surgeon, surgical assistant or the anesthesiologist performing the surgical anesthesia are not eligible for additional/separate reimbursement. When billed, these charges will be denied as included in the reimbursement made for the surgical/anesthesia procedure as a provider write-off.

Only the IOM supervising physician (MD or DO) including IONM supervising neurophysiologist who is dedicated to the monitoring of the patient and in constant attendance either in the operating room or at a remote location during the procedure, may be eligible for reimbursement. The site (operating room and/or remote location) and monitoring duration (length of time) must be clearly documented in the clinical records.

Remote IOM or IONM is eligible for reimbursement to the supervising physician if:

  • The recording lasts more than 30 minutes
  • The time spent performing or interpreting the baseline study is not counted as intraoperative monitoring
  • The technologist is in continuous attendance in the operating room performing the monitoring and communicating with the surgeon and the supervising physician
  • The remote supervising physician is in one-on-one real-time continuous contact with the technologist in the operating room
  • IONM services must be billed to the health plan where remote supervising provider rendering the IONM services is physically located/present at the time of service. The provider's billing office address does NOT determine the health plan where services should be billed

Reimbursement will not be allowed for services charged by or charges for, the technologist performing the IOM in the operating room as the reimbursement is included in the allowance for the supervising physician.

Professional or equipment charges billed by the surgeon, assistant surgeon, or anesthesiologist, or if billed by a non-physician or facility, are included in the global allowance of the procedure and additional reimbursement will not be allowed.

TOF monitoring should not be separately billed as it is considered integral to intraoperative monitoring and/or the administration of anesthesia and is primarily done to prevent or avoid permanent neurological injury. Therefore, TOF monitoring or any type of neuromuscular blockade testing, is not separately reimbursed.

This policy applies to all intraoperative monitoring regardless of the type.


American Medical Association (AMA). Current Procedural Terminology (CPT®). Chicago: AMA Press.

Centers for Medicare & Medicaid Services (CMS) National Correct Coding Policy Manual for Part B Medicare Carriers effective, 1-1-2024 Chapter 11 – L

BCBSA Inter Plan Policies - Chapter 5 - Claims Filing Rules

Cross References

Bundling Edits


Your use of this Reimbursement Policy constitutes your agreement to be bound by and comply with the terms and conditions of the Reimbursement Policy Disclaimer.