The average turnaround time for all tests was 57 minutes, compared to the 195-minute average time a patient spent in the ER. The longest wait was for a lactic acid level - it took an hour and 45 minutes to get results. Of the five common lab tests performed by emergency physicians, four can be completed within an hour at most hospitals, according to research published in 2004 in the journal Emergency Medicine. The only exception is a complete blood count, which can take longer if there are special tests needed or if more than one sample must be drawn. Emergency room labs typically take about an hour to report their findings back to doctors. That's not long when you consider that some patients require several tests done over multiple visits before they're released. For example, one study found that it takes on average 5 hours 30 minutes for an emergency physician to see his or her first patient in the morning and then another 50 minutes to write up the chart after completing all laboratory tests. However, it's important to remember that lab results don't always tell the whole story. For example, two people can have the same symptoms and receive different treatments based on their own unique histories. In addition, some diseases cause symptoms that can mimic those of other conditions.