National Clinical Coding Standards 
   ICD-10 5th Edition (2020)
   Accurate data for quality information 
             Terminology and Classifications Delivery Service
       
       
       
       
       
       
       
       
      National Clinical Coding Standards 
      ICD-10 5th Edition 
       
      Accurate data for quality information 
       
       
       
       
      Produced by: 
      Terminology and Classifications Delivery Service 
      NHS Digital 
      1 Trevelyan Square 
      Boar Lane 
      Leeds LS1 6AE 
      Information.standards@nhs.net 
      http://systems.digital.nhs.uk/data/clinicalcoding 
       
      Date of issue: April 2020 
       
      Copyright © 2020 NHS Digital
       
       
      ICD-10 CONTENTS 
      Introduction ............................................................................................................................. 3 
      Data Quality ............................................................................................................................ 6 
      National Clinical Coding Standards ICD-10 Reference Book ................................................11 
      Rules of ICD-10 .....................................................................................................................16 
      Conventions of ICD-10 ..........................................................................................................17 
      General Coding Standards and Guidance .............................................................................28 
      Chapter I Certain Infectious and Parasitic Diseases ..............................................................42 
      Chapter II Neoplasms ............................................................................................................52 
      Chapter III Diseases of the Blood and Blood-forming Organs and Certain Disorders Involving 
      the Immune Mechanism ........................................................................................................69 
      Chapter IV Endocrine, Nutritional and Metabolic Diseases ...................................................71 
      Chapter V Mental and Behavioural Disorders .......................................................................78 
      Chapter VI Diseases of the Nervous System ........................................................................86 
      Chapter VII Diseases of the Eye and Adnexa .......................................................................89 
      Chapter VIII Diseases of the Ear and Mastoid Process .........................................................91 
      Chapter IX Diseases of the Circulatory System .....................................................................92 
      Chapter X Diseases of the Respiratory System ..................................................................107 
      Chapter XI Diseases of the Digestive System .....................................................................111 
      Chapter XII Diseases of the Skin and Subcutaneous Tissue ..............................................117 
      Chapter XIII Diseases of the Musculoskeletal System and Connective Tissue ...................118 
      Chapter XIV Diseases of the Genitourinary System ............................................................126 
      Chapter XV Pregnancy, Childbirth and the Puerperium ......................................................133 
      Chapter XVI Certain Conditions Originating in the Perinatal Period ....................................163 
      Chapter XVII Congenital Malformations, Deformations and Chromosomal Abnormalities ..170 
      Chapter XVIII Symptoms, Signs and Abnormal Clinical and Laboratory Findings, Not 
      Elsewhere Classified ...........................................................................................................172 
      Chapter XIX Injury, Poisoning and Certain Other Consequences of External Causes ........180 
      Chapter XX External Causes of Morbidity and Mortality ......................................................201 
      Chapter XXI Factors Influencing Health Status and Contact with Health Services ..............212 
      Chapter XXII Codes for Special Purposes ...........................................................................229 
      Index of Standards ..............................................................................................................236 
      Summary of Changes ..........................................................................................................243 
           National Clinical Coding Standards ICD-10 5th Edition  
           INTRODUCTION 
           These national clinical coding standards are for use with the World Health Organisation 
           (WHO) International Statistical Classification of Diseases and Related Health Problems, 
                             th
           Tenth Revision 5  Edition (ICD-10) when translating diagnoses and other health related 
           problems recorded in a patient’s medical record for morbidity coding.  
            
           The classification of diagnoses using ICD-10 is a mandatory national requirement for the 
           NHS Admitted Patient Care (APC) Commissioning Data Set (which includes day cases) and 
           other data sets as outlined in the section below. 
            
                                             th
           WHO also refer to the ICD-10 5  Edition as the 2016 Edition. It includes updates that came 
           into effect between 2011 and 2016. 
            
           The WHO gives specific instruction on the use of the ICD-10 classification for morbidity 
           coding in some areas, whilst it provides options and guidance of a general nature in others. 
           This can lead to differences in interpretation and application of the classification and this, in 
           turn, can reduce the consistency and comparability of the data at local and national levels. 
           Specific instructions are provided in the following pages in the form of national clinical coding 
           standards for those areas of potential ambiguity (as far as practically possible) to safeguard 
           data consistency. 
            
           The coding of diagnostic statements or elements of them is ‘mandatory’ only where the 
           information is available in the medical record. The principles of the statistical classification, 
           particularly those relating to basic coding guidelines and the structure of the classification, 
           (as detailed in WHO ICD-10 Volume 2), are adopted as the standard and reinforced within 
           this book where appropriate. Where a standard within the WHO ICD-10 Volume 2 differs to a 
           national clinical coding standard, the national clinical coding standard must take precedence. 
           Background  
           The WHO states that ICD is to permit the systematic recording, analysis, interpretation and 
           comparison of mortality and morbidity data collected in different countries or areas and at 
           different times. The ICD is used to translate diagnoses and other health problems from 
                                                                                                             1
           words into alphanumeric codes, which permits easy storage, retrieval and analysis of data’ . 
            
           ICD-10 is a vital component of national data sets, such as Hospital Episodes Statistics (HES) 
           in England, Hospital In-patient Statistics (HIS) in Northern Ireland, Patient Episode Data for 
           Wales (PEDW), Scottish Morbidity Records (SMR), Cancer Registries, National Service 
           Frameworks, Care Pathways, Performance Indicators, Commissioning Data Sets (CDS) and 
           other Central Returns.  
                                         
           1
               World Health Organisation International Classification of Diseases and Related Health Problems’ ICD-10 
               Volume 2, 2.1 Purpose and applicability 
            
           3