A guide wire inserted into P to assist with a biopsy of an area in her lung dislodged. D proceeded with the biopsy but was unable to locate the dislodged wire. D determined that it was better to leave the wire and end the surgical procedure, rather than to extend the amount of time she was in surgery for him to continue searching for the wire. D informed plaintiff after the surgery that he could not find the wire, and that he had determined that it was better to leave it rather than continue the search procedure. P suffered and two months after the first procedure, D performed a second operation and successfully removed the wire with the use of a special X-ray machine known as a C-arm. P sued D for medical malpractice. P did not present any expert medical evidence. D moved to dismiss for failure to establish a prima facie case of medical malpractice in that P failed to show a deviation from accepted standards of medical practice, and also that such deviation was the proximate cause of P's injury. D pointed specifically to the failure to present any expert proof on the standard of practice. D also argued that res ipsa loquitur was inapplicable because there was no evidence of any error by D that caused the wire to become dislodged. P argued that expert testimony was unnecessary because D admitted that he intentionally left the wire inside P. Therefore, a jury could infer negligence given that there was no medical reason to leave the wire lodged in P, and D could have obtained a C-arm to locate and remove it. P also asserted that res ipsa loquitur applied because the wire was a foreign object that could only have been left in P as a result of D's negligence. D got the directed verdict. The Appellate Division affirmed. It rejected the contention that P had submitted sufficient proof under the doctrine of res ipsa loquitur to submit the case to the jury. Because P relied upon D's allegedly improper exercise of medical judgment, P could not rely upon the theory of res ipsa loquitur. P appealed.