Oh dear..oh dear...
The vet told me that Megat's abdomen will be shaved when they do the ultrasound to see the size of his organs. After cat-aunty's questions about GA, I read about how the ultrasound will be done and on of the sites http://www.petplace.com/cats/abdominal-ultrasound-in-cats/page1.aspx has this to say.
Is Sedation or Anesthesia Needed for an Abdominal Ultrasound? Neither sedation nor anesthesia is needed in most patients; however, some pets resent lying on their backs and may require some sedation to allow a diagnostic procedure. If a biopsy needle is used to obtain a tissue sample, a local anesthetic or ultrashort anesthesia is used.
One thing for sure. Megat is a very good patient and can sit at the vet for long hours without moving a muscle. He would even let the technician and vet move him about like a toy cat with hardly any protest. I have seen him offer all his limbs to the vet when its time for a blood test :) So I don't think there would be any GA but i would ask Dr FP anyway.