Hello! Welcome and thank you for asking on HCM! I understand your concern and would explain that the abdominal ultrasound is necessary to examine for possible liver structure changes or abdominal lymph nodes . Alkaline phosphatase is present in a number of tissues including liver, bone, intestine. Serum alkaline phosphatase is elevated in 2 main groups of conditions: -hepatobiliary disease (including obstruction from the stones, etc.) -bone disease associated with increased osteoblastic activity. So it is important an ultrasound to investigate for possible liver or billiary ways lesions. There is no special preparation before an ultrasound. But if the urinary tract is going to be examined, you should drink a lot of water before, in order for the urinary bladder to be full. This would help for better echographic images. Hope to have been helpful! Best regards! Dr. Iliri