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What is ICD-10?

ICD-10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD), a medical classification by the WHO. ICD-10 codes hold critical information about abnormal findings, complaints, diseases, epidemiology, external causes of injury, managing health, treating conditions, signs and symptoms, and social circumstances. There are more than 14,400 different codes in ICD-10 which can be further expanded to over 16,000 codes by using optional sub-classifications.

About ICD-10

The U.S. Department of Health & Human Services (HHS) has designated ICD-10 as a code set under the Health Insurance Portability & Accountability Act (HIPAA) and it will be required for use by physicians and others in the health care industry beginning October 1, 2015. It will replace all ICD-9 code sets. Thus, for any healthcare service that occurs on or after October 1, 2015, providers must use ICD-10 codes. This mandate applies to healthcare reimbursement, research, and reporting services. CMS has stated that they will offer no grace period and no additional delays for the transition.

Benefits of ICD-10

The U.S. has been using ICD-9 since 1979, and it is not sufficiently robust to serve the healthcare needs of the future. The content has limited data about patients’ medical conditions and hospital inpatient procedures, the number of available codes is limited, and the coding structure is too restrictive. Most developed countries have already made the transition to ICD-10 code sets, so the U.S. cannot compare U.S. morbidity diagnosis data at the international level.

ICD-10 code sets will enhance the quality of data for:

  • Tracking public health conditions (complications, anatomical location)
  • Improved data for epidemiological research (severity of illness, co-morbidities)
  • Measuring outcomes and care provided to patients
  • Making clinical decisions
  • Identifying fraud and abuse
  • Designing payment systems/processing claims

Through expanded categories and diagnosis codes, ICD-10 will foster a more accurate reporting system that will result in better clinical decision support. It also provides better data for measuring and tracking health care utilization and the quality of patient care. The granularity of ICD-10-is vastly improved over ICD-9 and will enable greater specificity in identifying health conditions.

  • The greater level of detail in the new code sets includes laterality, severity, and complexity of disease conditions, which will enable more precise identification and tracking of specific conditions.
  • Revised terminology and disease classification to be more consistent with new technology and current clinical practice.
  • Injuries, poisonings and external causes are much more detailed in ICD-10-CM. The codes include the severity of injuries, and how and where injuries happened. Extensions are also used to provide additional information for many injury codes.
  • Pregnancy trimester is designated for ICD-10-CM codes in the pregnancy, delivery and puerperium chapter.
  • Postoperative codes are expanded and now distinguish between intraoperative and post-procedural complications.
  • There are new concepts that did not exist in ICD-9-CM, such as under dosing, blood type, the Glasgow Coma Scale, and alcohol level.

Key differences between ICD-9 and ICD-10 codes

Comparison of Diagnosis Code Sets  
ICD-9-CM ICD-10-CM
3-5 Characters in length 3-7 Characters in length
First character may be alpha or numeric, characters 2-5 are numeric Character 1 is alpha; Characters 2 and 3 are numeric; characters 4-7 are alpha or numeric
Less specificity Greater specificity
Laterality not specified Laterality specified (e.g. left versus right)
Limited space for new codes Flexibility to add new codes


ICD-10-CM Code Structure
Characters 1 through 3 – Category
Characters 4 through 6 – Etiology, anatomic site, severity, or other clinical detail
Character 7 – Extension


ICD-10-CM Code Detail
S52 Fracture of the forearm
S52.3 Fracture of the shaft of the radius
S52.32 Transverse fracture of the shaft of the radius
S52.321 Displaced transverse fracture of the shaft of the right radius
S52.321A Displaced transverse fracture of the shaft of the right radius,initial encounter for closed fracture


How to prepare for ICD-10

The transition to ICD-10 is expected to be much more disruptive for physicians than previous HIPAA mandates, as they must adjust their documentation and other processes. Unlike previous HIPAA mandates where physicians could lean heavily on other partners, such as billing services, vendors, and clearinghouses, use of the new codes will require a much deeper level of involvement by the physicians themselves.

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