A killer whale at SeaWorld Adventure Park was getting a sonogram to prepare for possible artificial insemination when she knocked her trainer off a low wall Tuesday.

The 35-year-old trainer was taken to the hospital after suffering minor injuries after the bump from Orkid, a 5,900-pound whale, said SeaWorld spokeswoman Darla Davis.

"She just lost her balance," Davis said.

The trainer, who hit her head and side in the tumble, was taken to a University of California, San Diego, hospital for examination and released Tuesday afternoon, park officials said. Her name was not released.

The 19-year-old whale was getting her weekly ultrasound when she knocked the trainer off a wall next to the whale's tank, said Dave Koontz, another park spokesman. He said it was unclear if the whale intended to head-butt the trainer or accidentally bumped into her.

SeaWorld monitors all of its female orcas for potential insemination. The park is reviewing the mishap.

All but three of the 25 calves born in SeaWorld parks were conceived naturally, but the park hopes to use artificial insemination to bring genetic diversity to its whale population, said Dr. Todd Robeck, corporate director of animal reproduction for Anheuser-Busch Entertainment Corp., which owns SeaWorld.

"It's a lot easier to fly semen around the world than to fly a whale," Robeck said.

Whales are trained to roll on their sides so that veterinarians can put ultrasound probes against their flanks and monitor the orcas' ovaries. Doctors also take urine samples to track hormone levels throughout the whales' 42-day menstrual cycle.

Orkid is a few days from ovulating, Robeck said. An insemination will likely not be attempted until her next cycle, Robeck said.

Orkid, who was born in captivity, has not had any calves.

Last November, Orkid grabbed a trainer and pushed him under water during a show at Shamu Stadium, tearing a ligament in the trainer's left ankle. Koontz said trainers do not believe Orkid's behavior was aggressive.

That incident came two weeks before another trainer was bit and held underwater several times by Kasatka, a 7,000-pound killer whale, during a show at Shamu Stadium. The trainer escaped with a broken foot and was hospitalized for three days.