Medical errors in treating Medicare patients cost the program $8.8 billion from 2004 to 2006, according to a new study.

HealthGrades' study of patient safety found that the safety incidents also caused 238,337 preventable deaths.

The group's review of 41 million patient records found that errors were made in 3 percent of all admissions, and those who suffered an error had a one-in-five chance of dying.

Some of the medical errors counted in the survey were:

Accidental puncture or laceration

Complications of anesthesia

Bed sores

Failure to rescue

Foreign body left in during procedure

Selected infections due to medical care

Post-operative hemorrhage or hematoma

Post-operative hip fracture

Post-operative pulmonary embolism or deep vein thrombosis

Post-operative respiratory failure

Post-operative sepsis

Bed sores, failure to rescue and respiratory failure made up 63.4 percent of the incidents.

The issue could be critical for hospitals, which will stop getting reimbursement for some errors later this year.