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.
Reference
Panebianco NL, Jahnes K, Mills AM. Imaging and laboratory testing in acute abdominal pain. Emerg Med Clin N Amer . 2011;29(2):175-93. PMID: 21515175
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