The duration between injections should be consistent pain relief for the duration of the local anesthetic and/or steroid used. Assuming local anesthetic is used the duration between diagnostic injections is typically two weeks. In order to qualify for a repeat therapeutic injection, it is expected to have at least a 50% improvement in pain relief or function for at least three months therefore it would not be expected to repeat the injection at an interval shorter than three months. Exceptional circumstances that necessitate an earlier injection should be documented in the medical record.

If there has been an extended period of time from the initial diagnostic injections (e.g. two+ years) or there is a change in the symptoms that suggest there may be a different etiology repeat diagnostic injections may be utilized with documentation in the record as to why repeat injections are considered medically necessary.