A common problem for students of English is when to use articles like ‘a’ or ‘an’ and ‘the’.

In the example above, ‘the’ should replace ‘a’. This is because there are many kinds of diet: low-fat, high-protein, pureed, etc. If the recommendation is for one particular diet, we write ‘a low-fat diet’. The use of articles can be confusing, even for native English speakers.

We write 'the' when there is only one of something e.g. the Emergency Department or when the writer and the reader are clear which one is being discussed e.g. the local council will provide a home-care nurse.

Here are more examples of sentences where the definite article (the) is used:

Example 1: Please ensure he attends the clinic again for follow-up next week.
Why? The name of the clinic is already known by the reader.

Example 2: After admission, Mr Smith was admitted to the Medical Ward for observation.
Why? It is clear from the context of the letter, which medical ward is being referred to, i.e., the only one in the hospital.

Now here are examples of sentences where the indefinite article (a/an) is used:

Example 3: Please arrange for a social worker to visit Ms X as soon as possible.
Why? It is not important which specific social worker should visit; you are not referring to a known person.

Example 4: She should visit a dietician to discuss an improved dietary regime.
Why? There could be many different types of diets.

Keep in mind that there are instances when an article is not required. We often see this with medical conditions and medication names.

Introducing new information versus previously mentioned information

When you mention something of which there is more than one for the first time, the indefinite article a/an is usually required. This signifies to the reader that it hasn’t been mentioned before. However, the second and subsequent times that we mention it, definite article (the) is required because it is referring a specific thing.

For example:

Mr X was treated by a physiotherapist for 3 months. He made a successful recovery and after 3 months the physiotherapist recommended that he could return to work.

Test your knowledge with our quiz!

QUIZ: Can you choose the correct article to add to the blank spaces in these sentences?

1. Mr Khan has __ follow-up appointment in __ Out-Patients Department next week.
2. Mr X had a left hip replacement. __ operation was a success.
3. __ interpreter may be required, as she has limited understanding of English.
4. Initially, she came to the clinic on 03/07/06 for a blood test; however, results of __ blood test were negative.
5. The patient has __ family history of diabetes.

Want to know more about articles? Check out why symptoms need articles and which articles are used the most when describing them.