Please note these guidelines are intended as a clinical resource for clinicians performing preoperative evaluations. The author(s) have done their  best to assure the information is current and based upon  available evidence. Recommendations which are based on  authors' opinion(s) only (due to contradicting or lack of evidence from the literature) are italicized or specifically noted as such. When using this guide, keep in mind that it is only a guide and that even the best evidence may not apply to every patient situation. This information is not intended to replace the advice of a healthcare provider about diagnosis, treatment, or prognosis. The author(s) are not responsible for medical decisions that may be made based on information on this site since it is  provided for informational purposes. Patients should always consult their healthcare providers before deciding on a treatment plan.