1. Injuries that warrant further exploration solely by mechanism of injury: 
-unprotected (i.e. pedestrian vs vehicle, bike/motorcycle accidents, assault/battery with object)
-high-impact: unrestrained driver, death at scene, fall > 15 feet, ejection from vehicle, etc.
-vulnerable populations: immunocompromised, elderly, chronically ill, many other medical conditions.
2. Evaluating the abdomen s/p blunt trauma (i.e. car accident): 
-Abdomen looks benign, flat, no evidence of injury: can observe unless one of #1 is true.
-Severe abdominal pain: indicates presence of blood or GI contents (both peritoneal irritants), emergency ex-lap
-Significant superficial markers of damage (lots of bruising, a tire mark): need imaging; DPL/FAST if unstable, CT if stable.
-Coma: need imaging, DPL/FAST unstable, CT stable
-CXR showing diaphragmatic hernia or free air: emergency ex-lap
-Unstable vital signs with flat, unchanged abdomen: DPL/FAST, then OR.
-Unstable vital signs with distending abdomen: emergency ex-lap
-Unstable vital signs with obvious pelvis injury: DPL/FAST to r/o abdominal injury (if you see one, emergency ex-lap). Otherwise go to the angiography suite to try to embolize the bleed, also external fixation would be good.
3. Spleen/Liver injury: 
-Spleen/liver injury with perisplenic fluid and unstable vitals: go to OR.
-Grade III or less injury, stable- manage medically.
-Grade IV or higher injury, stable- manage operatively or with angiogram/embolization.
4. Injuries to root of the mesentery often require large forces, such that they are often accompanied by bowel injury. If you see suspicion of such injuries on CT, go to the OR.
5. Neuro trauma:
-LOC < 5 mins buys you observation in the ED for several hours (+/- CT scan, depending on attending)
-LOC >5 mins buys you CT scan, 24 hours obs
6. Coagulopathy in trauma can be due to: 
-Hypothermia-- leads to platelet and coag factor dysfunction. (Hypothermia can also lead to poor tissue perfusion and acidosis)
-Thrombocytopenia from DIC, sepsis, transfusion reaction. Transfuse to > 60