Let’s start at the beginning, ICD stands for International Classification of Diseases and was created by the World Health Organization (WHO). When thinking about the codes, it’s important to note the words International and World. Point being, ICDs were created for everyone not just those in the US; hence codes that cover macaw attacks. The Centers for Medicare and Medicaid (CMS) along with the National Center for Health Statistics (NCHS) reviewed the ICD 10s and modified them to include diagnoses and reason for visits for American healthcare; called ICD-10-CM (Clinical Modification).
In April of 2013, CMS released a quick reference guide/fact sheet1 which states that utilizing ICD-10-CM "will provide much better data for:
Measuring the quality, safety, and efficacy of care;
Reducing the need for attachments to explain the patient’s condition;
Designing payment systems and processing claims for reimbursement;
Conducting research, epidemiological studies, and clinical trials;
Setting health policy;
Operational and strategic planning;
Designing health care delivery systems;
Monitoring resource use;
Improving clinical, financial, and administrative performance;
Preventing and detecting health care fraud and abuse; and
Tracking public health and risks."
It may seem overwhelming to convert from 18,000 to over 140,000 codes, but sometimes more is better! Think of it as being told that the restaurant you are looking for is on 85th Street in NYC, but aren't told whether it's 85th Street East or West. Having all the details, whether it is the correct address for a restaurant or precise medical information could make a huge difference. Besides, walking the extra distance from East to West may result in ICD-10 code W22.02XA (walked into lamp-post initial encounter).
1 Centers for Medicare and Medicaid and Medicare Learning Network: http://www.cms.gov/Medicare/Coding/ICD10/downloads/ICD-10QuickRefer.pdf