What are ICD and OPS codes?

ICD and OPS codes were created in order to give structure to medical diagnoses and treatments and to name these in a standardized way.

The ICD code is a globally recognized system that is used to consistently label medical diagnoses. ICD stands for “International Statistical Classification of Diseases and Related Health Problems”. The new ICD-11 officially came into effect in January 2022, alongside version ICD-10, which continues to be valid. Both versions can be used for a transition period of 5 years. Codes continue to be used in accordance with ICD-10 until the introduction of ICD-11 in Germany.

“OPS” is short for “Operationen- und Prozedurenschlüssel” – the operation and procedure classification system. It serves as a coding system for operations and treatments.

Patients will find these codes in doctor’s letters and other medical documents. However, without an explanation, most people won’t understand what they mean, as the official diagnosis procedure classifications are written in medical terminology that is difficult to grasp for anyone who is not a healthcare professional.

gesund.bund.de in cooperation with “Was hab’ ich” provides you with clear and simple explanations of the ICD and OPS codes. Click here to access the ICD and OPS code search.

What do the letters and numbers stand for in ICD codes?

An ICD code uses a defined structure in which every letter and number has a meaning. In ICD-10 codes, the letters at the start and the two digits that follow these indicate the main category of a diagnosis. For example, the letter “J” is used to classify diseases of the respiratory system. J40 to J47 stand for chronic diseases of the lower respiratory tract, while J45 indicates asthma. Additional numbers after a dot can be used to indicate a more precise diagnosis. For example, J45.0 indicates predominantly allergic asthma, while J45.1 indicates non-allergic asthma.

The ICD code can be followed by additional indicators. These letters provide further information:

  • The additional indicators R (right), L (left) and B (both sides) represent the affected side of the body. This enables doctors to specify if the left knee, right knee or both knees are affected in the case of a torn cruciate ligament, for example.
  • The additional indicators A (excluded diagnosis), G (confirmed diagnosis), V (tentative diagnosis) and Z (condition after a confirmed diagnosis) indicate the diagnostic certainty. This enables doctors to specify, for example, whether a torn cruciate ligament has been reliably proven or – on the contrary – excluded.

The new ICD-11 classification

Since 2022, a new optional system of classifying diagnoses using codes has been available internationally. This is the ICD-11 – a revision of the classification system that has been updated to reflect modern healthcare standards. New chapters were created for improved classification of diseases. In addition, several codes can now be combined with one another to describe diagnoses in more precise terms. The logical structure is designed to make it easier than before to classify diagnoses more specifically using codes.

ICD-11 codes have a minimum of four and a maximum of six characters, the second character of which is always a letter. For example, the code for allergic asthma is J45.0 according to ICD-10. In ICD-11, it is now coded as CA23.0 – CA represents respiratory diseases, 2 indicates the lower respiratory tract, and 3 denotes asthma. The numbers after the dot indicate whether the asthma is allergic asthma (.0), non-allergic asthma (.1), other forms of asthma (.2) or non-specified asthma (.3).

There are no additional indicators for side of the body or diagnosis certainty anymore. Instead, these are indicated by code extensions that start with an “X” and are linked by means of an “&” with a primary code – for example, XK8G for left side of the body or XY7Z for a preliminary diagnosis.

What do the numbers stand for in OPS codes?

OPS (operation and procedure) codes are used to classify various tests and treatments.

The codes are revised annually and are organized into the following chapters:

  • 1: Diagnostic measures
  • 3: Diagnostic imaging
  • 5: Operations
  • 6: Medications
  • 8: Non-operative therapeutic measures
  • 9: Supplementary measures

Chapters 2, 4 and 7 were in an original version published by the WHO but are not used in the German healthcare system.

An OPS code is always a maximum of six characters long. The additional indicators R (right), L (left) and B (both sides) may also be used. The code begins with the chapter number, followed by a hyphen.

For example, desensitization (hyposensitization) for a person who is allergic to insect venom is classified using the code 8-030.0. Here, the number 8 indicates a non-operative therapeutic measure, 8-03 indicates immunotherapy, 8-030 denotes allergen-specific immunotherapy, and the extension .0 means that bee or wasp venom is used in the treatment.

What are these codes used for?

ICD and OPS codes provide an important basis for the billing of medical services provides, for the creation of statistics, and for quality reporting by hospitals.

ICD codes allow conditions to be classified in a clear and unambiguous way worldwide. This means, for example, that internationally comparable health and cause-of-death statistics can be created. However, the codes are not only useful in terms of patient care. They are also used in research, for example, to provide insights into the transmission or prevention of diseases.

Would you like to understand the ICD and OPS codes in your doctor’s letter or sick leave notice? “Click here to access the ICD and OPS code search