Ultrasounds can show obstructions in bile flow.
Not so much flukes itself unless you got such a massive infestation that it changes the smooth edges of the liver in a nodular cirrhotic surface.
Doing an ultrasound wouldnt hurt though. Cirrhosis, hepatic carcinoma, tumors, gall stones, fatty liver, enlarged liver will all show up.
But for liver flukes perhaps a blood test for various antibodies, eosinophils, LFT's, plus bilirubin and ALP would also be advisable?