If they had given her a blood test, chloroform might have turned up.
I also had a huge problem with the "Grey is family" line with her lawyer. Family or not, if you talk to your lawyer in front of a 3rd party (except possibly a spouse, or you are a minor accompanied by a parent, and that's not a guarantee) there is no privilege. Grey could be compelled to testify about anything Dex said, and her lawyer could possibly be, too. Sure, they could lie, but it's a terrible idea to lose attorney-client privilege.