Sorry to repeat myself, but just in case my post got lost unnoticed among those that appeared since...
People here mention a number of emergency conditions. Does anyone here have experience with pulmonary thrombosis? How common is it these days, and how best can it be detected?
IIRC, CT and Nuclear Medicine VQ scans can identify PEs. Ultrasound can look for possible source of clots (in legs most often, and arms - aka DVT) that can break loose and lodge in pulmonary vessels to cause PE.