There are twenty fields (fourteen before April 2007 and seven before April 2002), diag_01 to diag_20, which contain information about a patient's illness or condition. The field diag_01 contains the primary diagnosis. The other fields contain secondary/subsidiary diagnoses. The codes are defined in the International Statistical Classification of Diseases, Injuries and Causes of Death. HES records currently use the tenth revision (ICD-10). Prior to April 1995, the ninth revision was used (ICD-9). Diagnosis codes start with a letter and are followed by two or three digits. The third digit identifies variations on a main diagnosis code containing two digits. The third digit is preceded by a full stop in ICD-10, but this is not stored in the field.|Clinical Diagnosis|The A&E diagnosis code recorded for an A&E attendance. The CDS allows an unlimited number of diagnoses to be submitted, however, only the first 12 diagnoses are available within HES. The A&E diagnosis is a six character code made up of, diagnosis condition (n2), sub-analysis (n1), anatomical area (n2) and anatomical side (an1). Only certain diagnoses contain a sub-analysis.

diag_01