Final answer:
The EMT should perform a modified secondary assessment of the abdomen before completing the OPQRST on the chief complaint.
Step-by-step explanation:
The EMT should perform a modified secondary assessment of the abdomen before completing the OPQRST on the chief complaint. The OPQRST stands for Onset, Provocation, Quality, Radiation, Severity, and Time, which is a method used to assess the patient's pain or discomfort. The modified secondary assessment of the abdomen is important in this case because the patient is complaining of nausea and vomiting, which are symptoms that can indicate a problem in the abdominal region. By performing this assessment early on, the EMT can gather important information about the patient's condition and make appropriate treatment decisions.