Secondary survey following blunt trauma: a new role for abdominal CT scan.

Computerized tomographic (CT) scanning for blunt abdominal trauma has focused on initial emergency department evaluation. At our institution, CT scanning is often used on a delayed basis for unexplained drops in hematocrit, investigation of bony injuries, or subtle abdominal findings. We reviewed 268 such scans. Over 32 months, 487 CT scans were done for 5258 blunt trauma admissions. Of these scans, 268 (55%) were done 8-72 hours after admission on patients under observation. Scanning indications were a falling hematocrit (67%), associated injuries (28%), and abdominal tenderness (5%). Fifty of the 268 scans (19%) were positive for intra-abdominal abnormalities. Pleural effusions were seen in 82 (31%). Sixteen abdominal explorations were done. There was no difference in the pre-scan hematocrit drop in patients with normal scans (6.6%), positive scans (6.8%), and those who were explored (6.4%). There was one false positive (0.4%) and two false negative scans (0.8%). Conclusions. (1) A significant number of occult injuries, some life threatening, are detected by delayed CT scans. (2) Hematocrit drop under observation is not a good predictor of occult intra-abdominal injury. (3) Delayed CT scanning for occult abdominal injury is cost effective.