Introduction Technological developments and the introduction of hospital information systems have greatly promoted interest in the use of computer systems for recording findings and images at endoscopy. Several database systems have been developed for this purpose, most working only as a report generator. These systems are, however, hampered by the lack of a specific code system for endoscopic diagnoses and terminology. As a result of this shortcoming, the composition of reports and storage of data differ considerably between systems. Systems use different database structures and variable terminology and are thus not compatible or comparable. 1 2 3 4 The aim of this project is to develop a comprehensive code system for gastrointestinal endoscopic terminology, based on the widely accepted ICD-10 code system, that can be used in any gastrointestinal endoscopic information system. Methods 2 5 6 7 8 In the TRANS.IT project group, which was founded as a peer reference group, standard reports, text-blocks, and linkage to the new code system were discussed. A list of every endoscopic finding, intervention, or complication described using one of the three methods of report writing available for TRANS.IT users was generated. All items on this list were linked to a specific code. Results 1 Table 1 Different fields that need a specific code in endoscopic information systems Reason for endoscopy Medication use Sedation and medication during endoscopy Preparation Procedure for investigation Endoscopic diagnosis/findings Therapeutic and diagnostic interventions Histology results Therapy started Advice to referring doctor Complications We included all available standard reports, text-blocks, and diagnoses of Minimal Standard Terminology (MST) accepted by the TRANS.IT group. The endoscopic findings, interventions, and complications were extracted and linked to a specific code. In this way, a total of 316 standard reports and 1571 text-blocks were coded, to assure coding of every item within this project. In total, 2593 different items were extracted and received a specific code. Of these items, 630 (24%) could be coded with the existing ICD-10. Thus, 1963 new codes were required and added to the ICD-10 system, in order to be able to specifically code every endoscopic term. 9 spurting bleeding 2 Table 2 Comparison of ICD-10 and GET-C codes for gastric ulcer ICD-10 Description GET-C Description K25.0 Gastric ulcer, acute with hemorrhage K25.0 Gastric ulcer, acute with hemorrhage   K25.01 Gastric ulcer, acute with spurting bleeding (Forrest Ia)   K25.02 Gastric ulcer, acute with nonspurting active bleeding (Forrest Ib) K25.1 Gastric ulcer, acute with perforation K25.1 Gastric ulcer, acute with perforation K25.2 Gastric ulcer, acute with both hemorrhage and perforation K25.2 Gastric ulcer, acute with both hemorrhage and perforation   K25.21 Gastric ulcer, acute with spurting bleeding and perforation (Forrest Ia)   K25.22 Gastric ulcer, acute with nonspurting active bleeding and perforation (Forrest Ib) K25.3 Gastric ulcer, acute without hemorrhage or perforation K25.3 Gastric ulcer, acute without hemorrhage or perforation   K25.31 Gastric ulcer, acute with visible vessel (Forrest IIa)   K25.32 Gastric ulcer, acute nonbleeding with overlying clot (Forrest IIb)   K25.33 Gastric ulcer, acute with hematin-covered basis (Forrest IIc)   K25.34 Gastric ulcer, acute with clean ulcer ground (Forrest III) K25.5 Gastric ulcer, chronic or unspecified with perforation K25.5 Gastric ulcer, chronic or unspecified with perforation K25.6 Gastric ulcer, chronic or unspecified with both hemorrhage and perforation K25.6 Gastric ulcer, chronic or unspecified with both hemorrhage and perforation   K25.61 Gastric ulcer, chronic or unspecified with spurting bleeding and perforation (Forrest Ia)   K25.62 Gastric ulcer, chronic or unspecified with non- spurting active bleeding and perforation (Forrest Ib) K25.7 Gastric ulcer, chronic without hemorrhage or perforation K25.7 Gastric ulcer, chronic without hemorrhage or perforation   K25.71 Gastric ulcer, chronic with visible vessel (Forrest IIa)   K25.72 Gastric ulcer, chronic non-bleeding with overlying clot (Forrest IIb)   K25.73 Gastric ulcer, chronic with hematin-covered basis (Forrest IIc)   K25.74 Gastric ulcer, chronic with clean ulcer ground (Forrest III) K25.9 Gastric ulcer, unspecified, without hemorrhage or perforation K25.9 Gastric ulcer, unspecified, without hemorrhage or perforation   K25.91 Gastric ulcer, unspecified, with visible vessel (Forrest IIa)   K25.92 Gastric ulcer, unspecified, nonbleeding with overlying clot (Forrest IIb)   K25.93 Gastric ulcer, unspecified, with hematin-covered basis (Forrest IIc)   K25.94 Gastric ulcer, unspecified, with clean ulcer ground (Forrest III) 9 10 For several fields, there was no ICD-10 code available, and the item thus could not be categorized under an existing ICD-10 code. For example, the procedure for investigation and interventions could not be covered within the ICD-10 or even the ICD-10-CM system. Because these items are essential for good analysis of endoscopic data, a new chapter with the same structure as the ICD-10 was developed. The items in this new chapter start with the letters OG. We chose to categorize therapeutic interventions in this new chapter also because new therapies are developed frequently and can now be adapted. Adaptations were made in different chapters of the ICD-10. In Chapter 1, Certain Infectious and Parasitic Diseases (A00–B99), the exact locations in the gastrointestinal tract of some specific infections were added. In Chapter 2, Neoplasms (C00–D48), besides the exact locations in the gastrointestinal tract, the endoscopic characteristics of polyps were described and coded in more detail. It is important to register whether a polyp is pedunculated, sessile, or flat or has a villous endoscopic aspect. Also, the number of polyps found in a specific part of the intestine must be coded, because of important diagnostic and therapeutic options for patients and the follow-up of these patients. 11 Most changes were, however, made in Chapter 11, Diseases of the Digestive System (K00–K93). The description of esophagitis was divided into different origins and severity. Gastric and duodenal ulcers were coded according to the Forrest classification and their specific location in the stomach or duodenum. Gastritis and duodenitis were coded according to their specific location and the endoscopically suspected cause. Inflammatory bowel diseases were coded according to their endoscopic severity and location. Some complications related to gastrointestinal procedures were coded in more detail. In Chapter 18 symptoms, signs, and abnormal clinical and laboratory findings that are an indication for endoscopic investigations were coded in more detail. In Chapter 21 postoperative situations important for gastrointestinal endoscopic investigations such as gastric and colon operations were extensively coded. In the new, thirteenth chapter of the GET-C, about 446 new codes were generated. These codes start with the letters OG. The first part of this chapter includes coding of various indications for endoscopy that could not be categorized in the ICD-10. The second part consists of specific codes for detailed locations in the gastrointestinal tract. The third part includes procedures, which are divided into diagnostic and therapeutic procedures. Diagnostic procedures include, for example, sampling of histology and culture specimens. Examples of therapeutic procedures are different kinds of polypectomies, endoscopic mucosal resections, placement of endoprotheses, and dilatation of stenoses. Another aspect of these therapeutic interventions was used for the management of gastrointestinal bleeding such as injection therapy with or without coagulation, band ligations, and clipping. Preparation and procedure for the endoscopic examination are also coded in this chapter. The extensions of the GET-C were checked by the Dutch translation board of the ICD-10 to preclude any conflicts between the two code systems. Discussion The increased use of computer systems in health care and the need for communication between these systems necessitate the availability of generally accepted code systems. Good coding provides epidemiological information for research purposes. Coding is of importance for hospitals and professionals because most of the financial systems used in health care are based on different codes. In addition, good coding makes statistical analysis of different diagnoses and collection of rare diagnoses easier. With an internationally accepted code, it is possible to compare and share information in one field of interest. Most currently used coding systems are regional or national. Only some coding systems, such as the ICD-10, are translated into different languages and used in different countries. For endoscopic report writing and endoscopic databases, different systems have been developed. These systems are now being used at many hospitals. We used the Endobase III system from Olympus Europe in our project to compose reports and record different codes. The system runs as a network version with different workstations as well as a stand-alone unit. The Endobase III system enables the generation of reports via three pathways; in addition to standard reports and text-blocks, the latest translated version of the MST is also used to compose an endoscopic report. Thus it is essential that all differently generated data are coded in the same way to enable analysis of the data anonymously. In this system, all standard reports and text-blocks are linked to one or more specific GET-C codes. The choice of a standard report or text-block leads directly to the recording of the correct GET-C code in the Endobase III database. Due to the structure of the MST, the automatic link for it is more complex to realize. We chose to link the diagnoses with the GET-C code, which is separately selected within the MST by the endoscopist at the end of the report. Automatic linking is essential to ensure correct and complete selection of codes and to make the system workable for endoscopists. In the TRANS.IT project, an anonymous central database of endoscopic investigations was built. In this central database, only coded data instead of free text can be collected, for privacy reasons. After 3 years of use, a database of about 120,000 investigations using the same coding system has been built by this working group. The GET-C system allows the encoding of any data collected during endoscopic investigations and recorded in any endoscopic database. By extending the ICD-10 with respect to the structure developed by the WHO, it is always possible to extract the original ICD-10 code from the GET-C. Thus, it is possible to link the endoscopic database with other health-care systems throughout the world. Because endoscopy is an evolving medical specialty, new techniques are continuously becoming available. These require new codes, which will be discussed within the TRANS.IT project. 12