6.2 International Classification of Diseases

The ICD-10 is considered the international standard diagnostic classification system for all general epidemiological purposes, health data-management purposes, and clinical use, and is widely used in many countries as a classification system for diseases. Use of this standardized coding system will facilitate partnerships and collaborations with other programmes using the same coding system.

The ICD-10 is developed and maintained by WHO. The most recent version is available on the WHO website (12). It is available in the six official languages of WHO (Arabic, Chinese, English, French, Russian and Spanish), as well as in 36 other languages. A list of contact points for the 42 language versions of ICD-10 can be found on the WHO website (32).

On the WHO website, an ICD-10 interactive self-learning tool is available for training purposes (37). The ICD-10 has been used to classify diseases in health records and vital records, as a basis for the compilation of national mortality and morbidity statistics by WHO Member States. The ICD-10 codes are listed in alpha-numeric order and are described in detail.

Classification of structural congenital anomalies is found in Chapter XVII: “Congenital malformations, deformations and chromosomal abnormalities (Q00–Q99)”.

This chapter contains the following blocks of codes:

  • Q00–Q07  Congenital malformations of the nervous system
  • Q10–Q18  Congenital malformations of eye, ear, face and neck
  • Q20–Q28  Congenital malformations of the circulatory system
  • Q30–Q34  Congenital malformations of the respiratory system
  • Q35–Q37  Cleft lip and cleft palate
  • Q38–Q45  Other congenital malformations of the digestive system
  • Q50–Q56  Congenital malformations of genital organs
  • Q60–Q64  Congenital malformations of the urinary system
  • Q65–Q79  Congenital malformations and deformations of the musculoskeletal system
  • Q80–Q89  Other congenital malformations
  • Q90–Q99  Chromosomal abnormalities, not elsewhere classified.


ICD-10 modifications

The ICD-10 codes lack specificity for uniquely coding some congenital anomalies and most genetic syndromes. Therefore, some congenital anomalies surveillance programmes use their own local modification of the ICD-10 that contains additional codes for some specific congenital anomalies not found in the ICD-10, or add an extra digit, or both, to allow for more detailed coding of some defects and certainty of diagnosis.

The following is an example of how the RCPCH (formerly known as the British Paediatric Association) developed an adaptation of the ICD-10 by adding an extra digit to the ICD-10 codes to expand and allow for more detailed coding (38).

For example, in this adaptation, specific codes are added to differentiate parietal, orbital, nasal and nasopharyngeal encephaloceles, as follows:

  • Q01.8    Encephalocele of other sites (ICD-10 code)
  • Q01.80  Parietal encephalocele
  • Q01.81  Orbital encephalocele
  • Q01.82  Nasal encephalocele
  • Q01.83  Nasopharyngeal encephalocele