Which assessment finding in a patient complaining of back pain requires immediate action?

At 48 hours after a bowel resection surgery for colon cancer, the colostomy is noted to be moist and purple. Which additional assessment is most important?  

The 50-year-old previously healthy patient complains of shortness of breath, especially on exertion or when laying down to sleep. She takes over-the-counter allergy medicine for seasonal allergies and melatonin to help her sleep sometimes. Her vital signs are heart rate of 64 bpm, respirations 22, oxygen saturation 99%, and blood pressure 114/68 mmHg. Her assessment is notable for crackles over the bilateral lung bases and a moderate diastolic apical murmur. Her electrocardiogram is normal. Her echocardiogram shows normal function of the left ventricle and severe stenosis of the mitral valve. The nurse provides which information to the patient?