Use of Codes, Symbols, and Abbreviations

Standard MOI.4: The hospital uses standardized diagnosis and procedure codes and ensures the standardized use of approved symbols and abbreviations across the hospital.

In the 6th Edition, language was added to the intent and measurable elements of Standard MOI.4 to help clarify requirements related to the use of diagnosis and procedure codes, symbols, and abbreviations. In addition, a new measurable element was added, which prohibits the use of abbreviations in informed consent forms, patient rights documents, discharge instructions, and other documents patients and families receive from the hospital.

Standardization and uniform use of codes, symbols, and abbreviations can improve communication and understanding between health care practitioners, leading to safer and more effective care for patients. Appropriate use of abbreviations is particularly important. Numerous studies have focused on health care practitioners’ understanding and interpretation of abbreviations in medical documents, such as medical records, discharge summaries, and medication orders. Findings indicate that it is not uncommon for practitioners to have difficulty understanding the abbreviations used in their hospitals.1-4

To prevent misunderstandings and potential risks to patient safety, MOI.4 requires hospitals to establish lists for approved and do-not-use abbreviations and monitor for appropriate abbreviation use. There are resources for identifying abbreviations for the do-not-use list, such as the Institute for Safe Medication Practices (ISMP), which publishes a list of dangerous abbreviations not to be used due to frequent misinterpretation and associated medication errors.5 When developing lists, hospitals need to ensure that abbreviations on the approved list are not also on the do-not-use list, and vice versa. In addition, abbreviations can have only one meaning within the entire organization—for example, the abbreviation NKDA could mean “no known drug allergies,” or it could mean “nonketotic diabetic acidosis,” but it cannot have both meanings in an organization. 

Although hospitals identify an approved list of abbreviations, MOI.4, ME 5 requires that hospitals not use any abbreviations on patient materials and documents. It is important that patients and their families understand the information provided to them. A patient’s ability to comprehend information may be influenced by a low literacy level, language barriers, health condition, medication effect, stress or distraction from hospitalization, and/or other issues.6-8

Patients often do not fully understand the content of documents such as consent forms and discharge instructions.9-12 For example, research with patients recently discharged from the emergency department found the majority had limited knowledge and understanding of the instructions they received.9,10 Difficulties with understanding discharge instructions can affect a patient’s ability to care for themselves after their hospital visit and impact their knowledge about seeking follow-up care, among other issues. 

When abbreviations are used in documents given to the patient, the potential for misunderstanding can increase. Information needs to be clear and unambiguous to improve patients’ comprehension. Patients and their family members may not be familiar with the abbreviations used by their health care practitioners and the hospital, and they may not feel comfortable asking questions.

As stated in MOI.4, ME 5, "Abbreviations are not used on informed consent and patient rights documents, discharge instructions, discharge summaries, and other documents patients and families receive from the hospital about the patient’s care." No abbreviations of any kind should appear in informed consent documents, patient rights documents, and discharge instructions. These documents are meant for the patient and every effort should be made to increase the readability and clarity of the documents.

In the case of discharge summaries, they are generally not meant for the patient; however, a patient may receive the summary to give to his or her physician. Given that the discharge summary is intended for a physician, it is acceptable to spell out the term of an abbreviation the first time it appears in the document and include the abbreviation in parentheses next to it — once the meaning of the abbreviation has been established, the abbreviation can be used in the remainder of the discharge summary. It is important to use abbreviations that are commonly used across health care organizations and among practitioners. When an abbreviation is less known outside of the organization or clinical specialty, it is necessary to spell out the abbreviation throughout the discharge summary to prevent misunderstanding and confusion by the physician or health care organization that receives the summary. Please note, as it relates to MOI.4, ME 5, the practice of spelling out an abbreviation when first mentioned, then using the abbreviation thereafter in the document is acceptable only in discharge summaries. Abbreviations are not to be used in the other types of documents listed in the measurable element.

Laboratory test results sometimes go to patients, but it is not the intent of the standard for the abbreviations of the laboratory tests to be spelled out. When test results are given to patients, they are shared with their physician who can help explain the results. Hospitals may want to consider providing a separate form or resource to patients for information about the tests — such as a handout or website that has the names of common laboratory tests along with their definitions or descriptions. Results of diagnostic imaging studies also go to a patient’s physician, after interpretation by a radiologist. Commonly-known tests, such as MRI and CT, may be abbreviated; however, lesser-known tests may need to be spelled out along with the abbreviation so that patients see the full name of the imaging study that was performed. 

Use of standardized diagnosis and procedure codes and approved symbols and abbreviations must be monitored to ensure their use is appropriate and consistent across the organization. When issues are identified, the hospital takes action to improve these processes.


  1. Awan S, Abid S, Tariq M, et al. Use of medical abbreviations and acronyms: knowledge among medical students and postgraduates. Postgraduate Medical Journal. 2016;92:721-725.
  2. Chemali M, Hibbert EJ, Sheen A. General practitioner understanding of abbreviations used in hospital discharge letters. Med J Aust. 2015; Aug 3;203(3):147.
  3. Hamiel U, Hecht I, Nemet A, Pe’er L, Man V, Hilely A, Achiron A. Frequency, comprehension and attitudes of physicians towards abbreviations in the medical record. Postgraduate Medical Journal. 2018 Mar 14:postgradmedj online.
  4. Shilo L, Shilo G. Analysis of abbreviations used by residents in admission notes and discharge summaries. QJM: An International Journal of Medicine. 2018 Mar;111(3):179–183.
  5. Institute for Safe Medication Practices (ISMP). ISMP’s list of error-prone abbreviations, symbols, and dose designations. Accessed 22 March 2018 from 
  6. Jessup RL, Osborne RH, Beauchamp A, Bourne A, Buchbinder R. Health literacy of recently hospitalised patients: a cross-sectional survey using the Health Literacy Questionnaire (HLQ). BMC Health Services Research. 2017 Dec;17(1):52.
  7. Oliffe M, Johnston J, Freeman D, Bagga H, Wong PK. Assessing the readability and patient comprehension of medicine information sheets provided to patients by Australian rheumatologists. Annals of the Rheumatic Diseases. 2017;76:429.
  8. Smith AB, Agar M, Delaney G, Descallar J, Dobell‐Brown K, Grand M, Aung J, Patel P, Kaadan N, Girgis A. Lower trial participation by culturally and linguistically diverse (CALD) cancer patients is largely due to language barriers. Asia‐Pacific Journal of Clinical Oncology. 2017 Oct 30.
  9. Engel KG, Buckley BA, Forth VE, McCarthy DM, Ellison EP, Schmidt MJ, Adams JG. Patient understanding of emergency department discharge instructions: where are knowledge deficits greatest?. Academic Emergency Medicine. 2012 Sep 1;19(9).
  10. Engel KG, Heisler M, Smith DM, Robinson CH, Forman JH, Ubel PA. Patient comprehension of emergency department care and instructions: are patients aware of when they do not understand?. Annals of Emergency Medicine. 2009 Apr 1;53(4):454-61.
  11. Sherlock A, Brownie S. Patients' recollection and understanding of informed consent: a literature review. ANZ Journal of Surgery. 2014 Apr 1;84(4):207-10.
  12. Tamariz L, Palacio A, Robert M, Marcus EN. Improving the informed consent process for research subjects with low literacy: a systematic review. Journal of General Internal Medicine. 2013 Jan 1;28(1):121-6.