Here are a few natural ways to continue that sentence:

**"The doctor phoned the nurse because she was late for her shift."**

**"The doctor phoned the nurse because she was late to the patient consultation."**

**"The doctor phoned the nurse because she was late and he needed assistance with a procedure."**

Note: The pronoun "she" in the original sentence is ambiguous—it could refer to either the doctor or the nurse being late, depending on the context. The continuations above assume the nurse was late, which is perhaps the most common interpretation, but "she" could grammatically refer to either person.
