Expert testimony is generally required in a medical malpractice case to establish the standard of care and causation. The expert must practice in the same field of medicine, but not necessarily in the precise specialty.
“[T]o practice ‘in the same field’ means that a pharmacist may not define the standard of care for a physician and that a physician may not do so for a pharmacist. There is no general rule that prohibits a specialist from testifying regarding the standard of care applicable to a general practitioner or a specialist in one area from testifying about another area.” 
Expert testimony is not required where the determination of negligence does not require technical medical expertise, such as amputation of the wrong limb or leaving a foreign object in a patient during surgery.
This is not a substitute for legal advice. If you believe you have been the victim of medical malpractice you should consult with an attorney.
 McKee v. Am. Home Prods. Corp. , 113 Wn.2d 701 , 706, 782 P.2d 1045 (1989).
 Morton v. McFall, 128 Wn. App. 245 at 253 (2005), citing White v. Kent Med. Ctr., Inc. , 61 Wn. App. 163 , 173, 810 P.2d 4 (1991); Eng v. Klein , 127 Wn. App. 171 , 172, 110 P.3d 844 (2005).
 Miller v. Jacoby, 145 Wn.2d 65, 33 P.3d 68 (2001); Bauer v. White, 95 Wn.App. 663, 976 P.2d 182 (1989).