This Clinical Policy Bulletin expresses Aetna's determination of whether certain services or supplies are medically necessary, experimental and investigational, or cosmetic. Aetna has reached these conclusions based upon a review of currently available clinical information (including clinical outcome studies in the peer-reviewed published medical literature, regulatory status of the technology, evidence-based guidelines of public health and health research agencies, evidence-based guidelines and positions of leading national health professional organizations, views of physicians practicing in relevant clinical areas, and other relevant factors). Aetna makes no representations and accepts no liability with respect to the content of any external information cited or relied upon in this Bulletin. The discussion, analysis, conclusions and positions reflected in this Bulletin, including any reference to a specific provider, product, process or service by name, trademark, manufacturer, constitute Aetna’s opinion and are made without any intent to defame. Aetna expressly reserves the right to revise these conclusions as clinical information changes, and welcomes further relevant information including correction of any factual error. CPBs include references to standard HIPAA compliant code sets to assist with search functions and to facilitate billing and payment for covered services. New and revised codes are added to the CPBs as they are updated. When billing, you must use the most appropriate code as of the effective date of the submission. Unlisted, unspecified and nonspecific codes should be avoided. Each benefit plan defines which services are covered, which are excluded, and which are subject to dollar caps or other limits. Members and their providers will need to consult the member's benefit plan to determine if there are any exclusions or other benefit limitations applicable to this service or supply. The conclusion that a particular service or supply is medically necessary does not constitute a representation or warranty that this service or supply is covered (i.e., will be paid for by Aetna) for a particular member. The member's benefit plan determines coverage. Some terms in the CPBs may be worded differently in plan language. Some plans exclude coverage for services or supplies that Aetna considers medically necessary. If there is a discrepancy between this policy and a member's plan of benefits, the benefits plan will govern. In addition, coverage may be mandated by applicable legal requirements of a State, the Federal government or CMS for Medicare and Medicaid members. CMS's Coverage Database can be found on the following website: http://www.cms.hhs.gov/center/coverage.asp. More stringent state requirements may supersede the requirements of this policy. Under certain circumstances, your physician may request a peer to peer review if they have a question or wish to discuss a medical necessity precertification determination made by our medical director in accordance with Aetna's Clinical Policy Bulletin.