A patient has been taking heparin for three days and has developed hematuria. The most appropriate action for the nurse is to:

The correct answer is B: Hold the next dose of heparin and contact the physician. Hematuria (blood in urine) is a potential sign of heparin-induced thrombocytopenia (HIT), a serious adverse reaction to heparin. Stopping heparin is crucial to prevent further complications such as thrombosis. Contacting the physician is necessary for further evaluation and management. Inserting a urinary catheter (A) is not indicated as it does not address the underlying cause. Instructing the patient to drink fluids (C) is important for overall health but not the immediate priority in this situation. Administering an additional dose of heparin (D) is contraindicated due to the potential adverse effects already experienced.