Trauma Ultrasound
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 - Amount of fluid in belly?
  + if you just see a bit of fluid in Morrison's Pouch, there is 619 +/-
    100 mL of blood in the belly.

[Branney, S. W., R. E. Wolfe, et al. (1995). "Quantitative sensitivity
of ultrasound in detecting free intraperitoneal fluid." J Trauma 39(2):
375-80. The minimum volume of intraperitoneal fluid that is detectable
in Morison's pouch with ultrasound in the trauma setting is not well
defined. To evaluate this question, we used diagnostic peritoneal lavage
(DPL) as a model for intraperitoneal hemorrhage and undertook a blinded
prospective study of the sensitivity of ultrasound in detecting
intraperitoneal fluid. Participants included attending physicians and
residents in emergency medicine, radiology, and surgery. During the
infusion of the DPL fluid, participants continuously scanned Morison's
pouch until they detected fluid. All participants were blinded to the
rate of infusion and the volume infused. One hundred patients were
entered into the study. The mean volume of fluid detected was 619 mL.
Only 10% of participants detected fluid volumes less than 400 mL and the
overall sensitivity at one liter was 97%. We conclude that reliable
detection of intraperitoneal fluid in Morison's pouch requires a greater
volume than has been previously described.]

 - 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