Focused assessment by sonography in trauma

Definition

• • is a rapid, noninvasive means to identify hemoperitoneum in the trauma resuscitation area;

Indications

• • hemodynamically unstable patient without obvious indication for laparotomy;

  • any patient requiring prompt transfer to the OR for nonabdominal cause;

  • use as a screening test for all others requiring abdominal evaluation.

Contraindications

• • obvious need for laparotomy

  • lack of FAST expertise.

Accuracy

• • Sensitivity and specificity (60% to 85%)

  • less than those of CT in detection of hemoperitoneum.

  • not accurate for the detection and anatomic characterization of solid organ injury.

  • a negative FAST should generally be followed by a more definitive diagnostic test (CT or DPL) in the patient incurring high-energy injury.

Advantages

• • rapid and noninvasive;

  • no need to transfer the patient to the radiology suite;

  • can be performed by a trained member of the trauma team;

  • can be repeated;

  • less expensive than CT.

Disadvantages

• • Can miss solid organ injury in the absence of hemoperitoneum or small amounts of hemoperitoneum;

  • cannot distinguish between ascites, succus entericus and blood;

  • requires specialized training and competency;

  • difficult to interpret in the obese or patients with extensive subcutaneous emphysema.

Technique of FAST

• • A 3 to 5.0 MHz transducer is placed in the subxiphoid region in the sagittal plane to set the machine gain.

  • Sagittal views of Morison’s pouch and the splenorenal recess are performed, followed by a pelvic transverse view.

  • Free fluid appears anechoic (black) compared with the surrounding structures.