What is the test for using expert testimony in a medical malpractice case?

whose irrelevance, unreliability, or potential for prejudice outweighs its proper probative value." ' [Citation.] [] Nonetheless, '[b]ecause an expert's need to consider extrajudicial matters, and a jury's need for information sufficient to evaluate an expert opinion, may conflict with an accused's interest in avoiding substantive use of unreliable hearsay, disputes in this area must generally be left to the trial court's sound judgment.' " As the court observed in People v. Bell (2007) 40 Cal.4th 582, 608, " '[m]ost often, hearsay problems will be cured by an instruction that matters admitted through an expert go only to the basis of his opinion and should not be considered for their truth. [Citation.]' "