Whoever stole four colonoscopes from Armstrong County Memorial Hospital last weekend probably knew what they were doing.

The long, flexible tubes used to visually exam a patient's colon are as valuable as precious gems -- and nearly as easy to steal.

"It's a lot more common than you'd think," said Scott Mason, sales and purchasing director for Endoscopy Resources Inc., of Port Orange, Fla., which deals in used endoscopes and colonoscopes.

Because the scopes are packaged in a small, black briefcase, someone carrying one through a hospital lobby likely wouldn't draw attention, Mason said. "It looks like you could be carrying a laptop."

And once out of the hospital, a $22,000 colonoscope can fetch $15,000 in overseas markets or from unsavory domestic companies or practitioners. State police valued the four scopes stolen from Armstrong Hospital at $103,680.

Officials at the East Franklin medical center could not be reached for comment yesterday.

Mason said his company had to tighten its policies on sales and purchases after nearly buying stolen equipment three years ago. When they bid on an endoscope listed on eBay -- and there were several listed on the online auction Wed site yesterday -- the FBI contacted them to say it was stolen. They set up a sting buy and the culprits, based in Oklahoma, were arrested.

Another time, Mason said his company made a $60,000 bid for 12 scopes with a third-party wholesaler in California. When the serial numbers didn't check out, they called the police. Now, Endoscopy Resources will not buy any equipment unless the other party can verify it's not stolen.

"You can't just take a person's word," Mason said. "We even check up on doctors who want to buy from us."

Meanwhile, to deter thefts, Mason said some hospitals have set up surveillance cameras in areas where scopes are stored, or require physicians to sign out the equipment with an identification card.

The Associated Press yesterday reported that police in State College are investigating the theft of two colonoscopes, worth $46,700, stolen from Mount Nittany Medical Center in July.

The report also noted that one Florida hospital had 19 endoscopes stolen in 2002.