Trauma Ultrasound
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 - Protocol for blunt abdominal trauma ultrasound
  Free Fluid:
   unstable: OR
   stable: CT scan
  Equivocal:
   unstable: DPL or OR
   stable: CT scan or DPL
  Negative:
   observe and repeat U/S later
  [Rozycki GS, Shackford SR. Ultrasound, what every trauma surgeon should
  know. J Trauma 1996;40:1-4.]
 - Protocol for penetrating thoracic trauma
  Positive: to OR
  Equivocal: to OR for pericardial window
  Negative: observe

 - Sensitivity
  + ultrasound sensitivity for free fluid:  98%, specificity of 99%, +
    predictive value of 100%
  + ultrasound sensitivity for site of fluid origin:  86.6%, positive predictive
    value of 92%
  + ultrasound least useful at detecting diaphragm injury, hollow viscus,
    biliary, or vascular injury.
  + main complicating factor is subcutaneous emphysema that limits usefulness.
    [Goletti O et al.  The role of ultrasound in blunt abdominal trauma:
    results in 250 consecutive cases.  J Trauma 1994;36:178-180.]
 - Check for fluid:
  + in Morrison's Pouch between liver and kidney
    NOTE that Glisson's Capsule around the liver is very thin, but that
    sometimes there is perinephric fat and excess connective tissue around the
    kidney that may give the appearance of "pseudo-fluid"
  + in left paracolic gutter
  + on either side of bladder, low.
 - Morison's pouch is most sensitive
 - Pietzman says:
  + Peritoneal signs:  go to OR for laparotomy
  + questionably peritoneal signs:  DPL still has a role
  + no peritoneal signs:  ultrasound