Did you know 90% of the medical bills we receive contain errors??? Many of these consist of double billing and tests we never received! How to spot them can be easy if you take the time. First, ask for an itemized version  of your bill which should include current procedural terminology (CPT) codes that doctors use to denote their services. Then go to the American Medical Association at AMAASSN.org to sign up to get FREE access to the list of codes. If you spot any, call your insurer to dispute.