20 weeks sonogram shows echogenic foci in 4 chamber heart and cystic areas seen bilaterally in fetal kidney measuring 3mm. Tested neg for ds, worried?

MFM consult. Maybe a consultation with a maternal fetal medicine specialist can help putting the findings for you into prospective and help you not to worry.
Not likely. Your doctor is the best one to ask since he or she has all the details. An echogenic intracardiac foci is basically a variation of normal if your genetic blood testing was normal and there are no other abnormalities were seen. There is not enough detail to comment of the kidney.