Final answer:
The nurse should interrupt the infusion and notify the practitioner of the aPTT result.
Step-by-step explanation:
The nurse should interrupt the infusion and notify the practitioner of the aPTT result. An aPTT value of 98 seconds indicates that the client's blood is not clotting adequately and is at risk for bleeding. The nurse should alert the practitioner to this abnormal result so that appropriate action can be taken to prevent complications.