Bosentan is contraindicated in pregnancy due to significant teratogenicity; therefore, it is most important that the nurse verify a negative human chorionic gonadotropin test in the patient prior to administering it. It can also cause hepatotoxicity, so serum aminotransferase levels must be obtained for a baseline and then monitored regularly. Although review of the echocardiogram results may be helpful to verify the necessity of bosentan, this is not the most critical test to review. Bosentan does not cause renal failure, so BUN and creatinine are less important to review.