Sometimes they get the right and left bit sorted out, but still carry out the wrong procedure on the patient, or they get the procedure right, but on a patient who should never had it in the first place.

All of these blunders have a medical name, of sorts, and they're known by the acronym WSPEs, which stands for 'wrong-side/wrong-site, wrong-procedure, wrong-patient' adverse events.

These mistakes are so basic that you'd think they are rare enough to be virtually non-existent. You'd be wrong. One study estimates that between 1,300 and 2,700 WSPEs occur every year in America, which, at the high end, suggests more than seven a day.

Even these estimates may be conservative. Researchers found that WSPEs are rarely reported - and with the threat of litigation looming, this is perhaps not so surprising. Instead it is often left to the newspapers to announce the blunder, having interviewed the patient, if he has survived, or his relatives.

Orthopaedic surgeons and dentists seem to commit the most WSPE blunders, while the more common errors are to do with the wrong treatment or wrong procedure.

So perhaps more doctors know their right from their left than we thought.

(Source: Archives of Surgery, 2006; 141: 931-9).