Final answer:
The nursing interviewing skill used when referring back to a patient's previously mentioned issue with their colostomy is known as focusing. This technique helps to concentrate the conversation on a specific area of concern to obtain more detailed information.
Step-by-step explanation:
The interviewing skill being used when the nurse says, "you mentioned before that you are having a problem with your colostomy" is focusing.
Focusing is a communication technique used in the nursing profession to steer the conversation back to a specific topic that was previously discussed or to narrow down a broad topic to something more specific. This technique helps in gaining more detailed information about a particular issue that the patient has mentioned, ensuring that important health concerns are thoroughly explored and addressed during the patient assessment.