Blue Cross-Blue Shield is asking the nation's hospitals to eliminate nearly $400 million worth of routine lab tests and X-rays every year, saying the tests are unnecessary and sometimes harmful.

The latest step in this direction by the country's largest health insurer came as a recommendation that member plans quit paying for routine tests before surgery unless the tests are specifically ordered by the surgeon. The recommendation was made yesterday by Blue Cross-Blue Shield president Walter McNerney.

On Feb. 6 Blue Cross-Blue Shield urged its state and local plans to stop paying for routine admission tests for non-surgical patients unless they, too, are ordered by the patient's doctor.

Hospitals give $1.3 billion worth of nonsurgical admission tests and $1.1 billion worth of presurgical tests a year, McNerney estimated.

He told a news conference here that on a conservative basis hospitals should be able to save patients $200 million a year by eliminating unneeded nonsurgical admission tests and $180 million to $200 million by eliminating unneeded presurgery tests.

The fact, is he said, overtaking may hurt the patient, because such tests sometimes result is "false positive" readings that lead doctors to do further unnecessary and sometimes harmful probing and treating.

Dr. C. Rollins Hanlon, director of the American College of Surgeons, agreed. "In many instances, good medicine is less expensive than bad medicine," he said.

Many tests and X-rays are vital, he maintained, but the correct number for any patient is the minimum "consistent with the patient's safety and quality of care."

The District of Columbia Medical Society has made a similar set of recommendations, but a recent check showed that many hospitals here still give routine admission test batteries whether a patient's doctor orders them or not.

McNerney said he is confident that within a year that will no longer be the case, because by then most of the nation's 130 Blue Cross and Blue Shield plans will no longer be paying for unordered tests.

At that point, he said, if he were a patient and a hospital gave him a test wasn't ordered by his doctor-and the hospital tried to charge him-he wouldn't pay.