Error Number 189. Mistaking the term "midnight" and the abbreviations used for 12 noon and 12 midnight

A doctor wrote the following order:

The nurse interpreting the order assumed midnight to be between 1/30 and 1/31. So she continued to give the medication during the day on January 30th. The attending doctor questioned the nurse as to why his patient was still receiving medication when he specified the time for termination. The nurse explained her interpretation of the order. The doctor realized what had happened and explained he intended the medication to be stopped midnight between 1/29 and 1/30.

According to the Time Service Division of the Naval Observatory in Washington, D.C., this is a common problem. They recommend the following solutions.

1. Designate midnight using the date falling before and after midnight. For example, 12 midnight on 1/30 should be listed as 12 midnight (1/29-1/30).
2. Use schedules (have doctors' orders) that specify 12:01 or 11:59 (this seems impractical for hospitals). This system is used by railroads.
3. Use military time systems. 0100 (1 AM) to 0000 (12 midnight). This system is in use by airlines and the military. Unfortunately, most people (including military personnel) believe that 2400 is the last number in the system but there's no such number-it's 0000 or 0 h. Using 2400 makes one think it is the end of the day, which it is not.

Another issue which is confusing is whether midnight is 12 a.m. and noon is 12 p.m. (right) or vice versa (wrong). Again, different people have different opinions. This can also lead to medication error. The National Bureau of Standards recommends that, because of their ambiguity, the abbreviations 12 a.m. and 12 p.m. never be used. They suggest the terms noon and midnight be used instead or, more precisely, 12 noon and 12 midnight with no abbreviation.