TUESDAY, June 17 (HealthDay News) -- As the war in Iraq shifted after the fall of Baghdad to one in which U.S. troops were battling insurgents, the types and severity of injuries suffered by the Marine Corps became more severe and deadly.

That's the finding of a new report by a former U.S. Navy physician who served twice in Iraq. In the second "insurgency" phase of the war, it has also taken longer to transport the wounded to medical care, resulting in more Marines dying from their wounds, the report said.

The primary reason for the changes in the Iraq war owe to changes in the nature of the battlefield, said Dr. Stacy A. Brethauer, a staff surgeon at the Cleveland Clinic. "It's an urban battlefield and improvised explosive devices have changed the injury patterns," he said. "The type of battle has changed, and that is reflected in the types and severity of injuries."

"We found a difference in the severity of casualties and the overall mortality rates within the 1st Marine Expeditionary Force when we compared the use of a forward mobile surgical unit during the invasion compared to the insurgency," Brethauer added.

The Iraqi invasion was the first time forward mobile surgical units were used. These units can provide almost immediate surgical care to wounded front-line troops, Brethauer said.

When the 1st Marine Expeditionary Force returned to Iraq 2004, those surgical units were still used, but in a different way, Brethauer said. "They were positioned in stationary locations, and they did not move while we were there," he said.

"We looked at the data from the first invasion to what we were experiencing during the insurgency," Brethauer said. "We saw significant differences in the severity of wounds we were seeing and the number mortalities we were seeing."

The findings are published in the June 16 issue of the Archives of Surgery.

For the study, Brethauer's team looked at records from a combat trauma database for 338 casualties treated during the first phase of the war, as well as 895 casualties during the insurgency phase. Compared with the initial phase of the war, there were more major injuries per Marine during the insurgency (2.4 compared to 1.6). There were also more fragment wounds during the insurgency, (61 percent versus 48 percent). But, there were fewer gunshot wounds during the insurgency (33 percent compared to 43 percent), the report found.

Since the start of the insurgency, it has taken longer for injured Marines to reach surgical units than it did during the initial phase of the war. Patients wounded during the insurgency reached surgical units, on average, 59 minutes after injury, compared with 30 minutes during the initial phase of the war, Brethauer said.

Also, the number of Marines killed in action before reaching a surgical unit has risen to 20.2 percent since the insurgency, from 13.5 percent during the initial phase of the war. And Marines who died from their wounds also increased during the insurgency, from 0.88 percent to 5.5 percent, Brethauer said.

Mortality rates during the insurgency have risen to rates seen in other wars, such as Vietnam, Brethauer said. "The invasion had an exceptionally low rate of people being killed in action and dying of wounds," he said. "When we got into the insurgency, we saw what we had seen in prior major conflicts, which is around a 20 percent killed-in-action rate and a 5 percent died-of-wounds rate."

To cut down on deaths, Brethauer recommended moving the surgical units closer to the battle site and bypassing battalion aid stations for the most critically injured patients.

More information

For more on Iraq war deaths and injuries, visit iCasualties.org.