Final answer:
The nurse should monitor vital signs closely as the first action when performing a needle biopsy of the liver. Administering pain medication and applying pressure to the biopsy site may be necessary after the procedure. Placing the client in a prone position is not typically required for a liver biopsy.
Step-by-step explanation:
The nurse should monitor vital signs closely as the first action when performing a needle biopsy of the liver. Monitoring vital signs allows the nurse to assess the client's physiological response to the procedure and identify any changes that may require immediate intervention. This includes monitoring the client's blood pressure, heart rate, respiratory rate, and oxygen saturation.
Administering pain medication and applying pressure to the biopsy site may be necessary after the procedure to manage any discomfort or bleeding. However, these actions would occur after monitoring vital signs and ensuring the client's stability. Placing the client in a prone position is not typically required for a liver biopsy, as the procedure is often performed with the client lying on their back.