In the most recent EM Clinics of North America publication, Dr. Panebianco et al. discussed the evidence behind diagnostic tests for acute abdominal pain. There were some really great teaching points in this broad-reaching topic.
My favorite pearl: A 3-way acute abdominal series is too insensitive to rule-out any major acute causes of abdominal pain with confidence. So stop ordering them routinely. If you are worried about a perforated viscus, order an upright chest x-ray instead — more accurate and less radiation.
Adapted from  Go to ALiEM (PV) Cards for more resources.
- Panebianco N, Jahnes K, Mills A. Imaging and laboratory testing in acute abdominal pain. Emerg Med Clin North Am. 2011;29(2):175-93, vii. [PubMed]