Objective: To identify the performance of Focused Assessment Sonography in Trauma (FAST) in detecting hemoperitoneum in blunt abdominal trauma patients at the emergency room.

Meterials and methods: The diagnostic results of blunt abdominal trauma patients assessed using the FAST in the emergency room of Songklanagarind Hospital during 1 January 2008 and 30 June 2008 were compared with the diagnostic results of abdominal computed tomography (CT) scans, diagnostic peritoneal

lavage (DPL), exploratory laparotomies and discharge results. Sensitivity, specificity and accuracy were calculated.

Result: There were 999 traumatic patients during the 6-month study period. FAST was performed in 291 patients (29.0%) with a mean age of 34.6ฑ15.3 years, 227 men (78.0 %) and 64 women (22.0%). The most common injuries were motorcycle accident (61.9%), car accident (19.9%) and falls (6.5%). The FAST results were positive in 18 patients. FAST had a sensitivity of 54.8 %, a specificity of 99.6 %, an accuracy of 94.8%.

Conclusion: FAST examination had limitation for screening hemoperitoneum in blunt abdominal trauma patients. The positive result is reliable in detecting intra-abdominal free fluid. In cases of negative result, it could not exclude intra-abdominal free fluid and should be follow by serial abdominal examination or confirmatory tests such as CT abdomen or DPL.