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Out-of-Hospital Premises Standard: Image Guidance When Administering Nerve Blocks for Adult Chronic Pain

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Recognizing that this Standard contains new expectations that may require time for physicians to adjust how they practice, CPSO has implemented a formal transition period to allow physicians to align with the new expectations. This transition period will end on Sunday, September 3, 2023.

The use of image guidance is widely accepted as a critical component of administering nerve blocks in order to reduce the risk of complications, ensure the injection is delivered to the target, and enhance patient safety.

In keeping with our mandate to serve the public interest, this Standard sets out the College of Physicians and Surgeons of Ontario’s (CPSO) expectations for physicians administering nerve blocks for adult chronic pain in Out-of-Hospital Premises.


This Standard only applies to nerve blocks administered for adult chronic pain in Out-of-Hospital Premises.


  1. When administering nerve blocks for adult chronic pain physicians must practise in a manner that is consistent with this Standard, relevant practice standards, quality standards, and clinical practice guidelines.
  2. Physicians administering neuraxial, paravertebral and plexus nerve blocks for adult chronic pain must use image guidance.
  3. Physicians administering all other nerve blocks for adult chronic pain must use image guidance where indicated in the circumstances, taking into account:
    1. the depth of the nerve being blocked;
    2. proximity to the neuroaxis and/or other vital structures1;
    3. whether the patient has abnormal or challenging anatomy;
    4. whether the patient has had an injury or undergone previous surgery in the area where the nerve block is to be administered that may affect the anatomy or spread of medications; and
    5. the potential harm to the patient were the block to be administered incorrectly.
  4. When using image guidance physicians must:
    1. capture an image demonstrating appropriate placement (e.g., an image of needle placement, appropriate contrast spread, or local anesthetic spread) and maintain a copy of the image in the patient’s medical record or documentation of how and/or where the image can be accessed;2
    2. ensure that the level of imaging used (e.g. ultrasound, computerized tomography (CT) and/or fluoroscopy) is appropriate for the type of nerve block being performed;
      1. For example, it is not appropriate for ultrasound to be used for all nerve blocks. CT and/or fluoroscopy must be used where clinically indicated;3
    3. be qualified and able to perform the required level of imaging within their premises or have a process in place for the timely referral of patients to a qualified health care professional.4


1. For example, major blood vessels and internal organs.

2. Images must be retained in accordance with CPSO’s Medical Records Management policy.

3. Please see the Advice to the Profession document for additional information on practice standards, quality standards, and clinical practice guidelines that indicate where CT and/or fluoroscopy are necessary for proper visualization.

4. For example, physicians practising in premises with only ultrasound available, need to have procedures in place for the referral of patients in the event that CT and/or fluoroscopy is indicated for proper visualization.