Giolito, 18, will visit Lewis Yocum, the doctor who performed Tommy John surgery — an elbow ligament replacement procedure — on Nationals pitchers Stephen Strasburg and Jordan Zimmermann. Nationals team doctor Wiemi Douoguih examined Giolito, but the Nationals are seeking a second opinion from Yocum. As soon as Giolito can be examined, he will fly out to Los Angeles.

“If he needs surgery, we’re going to give him the surgery,” Rizzo said. “There’s no sense in delaying it.”

The Nationals selected Giolito with the 16th overall pick and signed him moments before the July 13 deadline, even though he had suffered an elbow injury during his senior year of high school.

Giolito threw in his first professional baseball game on Aug. 14, allowing one run on two hits but lasting only two innings in a Gulf Coast League outing. He was pulled after he experienced soreness in the same elbow. The injury was first reported by ESPN.com.

Giolito said in June that the initial elbow injury was treated at the Kerlan-Jobe Clinic in Los Angeles, where Nats pitchers Stephen Strasburg and Jordan Zimmermann underwent Tommy John surgery, and that it would not likely lead to surgery. The Nationals agreed that a cautious rehabilitation route, instead of surgery, was the best approach and sent the pitcher down to Viera, Fla., in mid-July to continue his rehab under the Nationals minor league coaches.

Giolito didn’t experience any discomfort during his rehab process leading up to his first start, Rizzo said.

Giolito was considered among the top prospect in the Nationals’ system. Some viewed him as a possible first overall pick before he strained the ulnar collateral ligament in his right elbow ligament during his senior season at Harvard-Westlake School in Studio City, Calif.

“We knew when we drafted him this was an issue,” Rizzo said. “We were comfortable with the fact that the worst-case scenario was Tommy John surgery and we’ll see if that’s where we’re headed. Going into this with our eyes wide open and we thought this was scenario and a possibility.”

Giolito has thrown his fastball 100 mph, along with a hard curveball and improving change-up. He was weighing a scholarship offer to play baseball at UCLA or signing with the Nationals.