WASHINGTON (Reuters) - The use of acupuncture before and during surgery reduces patients' post-operative pain as well as the need for pain-killing medication, researchers said on Tuesday.

Researchers at Duke University Medical Center in North Carolina analyzed the results of 15 clinical trials on the effectiveness of acupuncture -- a practice that originated in China of inserting thin needles into specific body points.

They concluded that it is valuable for pain control in surgery patients.

The 15 trials showed that patients getting acupuncture before or during various types of operations had significantly less pain afterward than patients who did not get acupuncture.

These patients also required less morphine or other opioid pain medication after surgery, which reduced the side effects like nausea and vomiting from these types of drugs, the researchers said.

In terms of pain-drug side effects, the acupuncture patients experienced 1.5 times lower rates of nausea, 1.6 times fewer reports of dizziness and 3.5 times fewer cases of urinary retention compared to the other patients, the study found.

These findings augment a growing body of evidence on the value of acupuncture in improving the surgical experience for patients, the researchers said.

For instance, the National Institutes of Health says that acupuncture has also been shown to reduce nausea after chemotherapy and surgery.

"The use of acupuncture is still very under-appreciated," Dr. Tong-Joo Gan, vice chairman of Duke's anesthesiology department, said in a telephone interview.

"Western doctors are typically not trained (in acupuncture) and they really are not familiar with how it works," Gan said. "I think practitioners such as surgeons and anesthesiologists need to have an open mind."

He said numerous studies have looked at acupuncture to reduce post-operative pain, but many of them were not very well done. Gan said his team identified a group of well-controlled studies to judge how well acupuncture worked.

"I do it all the time," Gan said. "You give patients the acupuncture about half an hour before surgery and continue during surgery. It can reduce post-operative pain."

According to the U.S. National Institutes of Health, scientists do not fully understand how acupuncture works, believing it might help the activity of the body's pain-killing chemicals or affect the regulation of blood pressure and flow.

"I think it is generally applicable to a number of different procedures," Gan said. "In the studies, we looked at abdominal procedures, orthopedic procedures, gynecological procedures."

The research was presented at a conference of the American Society for Anesthesiology in San Francisco.