Avoiding standing for long periods of time is necessary when you are experiencing a bout of hemorrhoids.
This situation should be avoided.
As you can imagine the forces of gravity of your entire body are all pulling down in the direction of the anus when in a standing position.
In so doing , you are involuntary adding a lot more pressure on the anus area. This situation may help in aggravating the hemorrhoids further.
This aggravation may manifest itself in different ways like making the hemorrhoids bleed even more and or swell the hemorrhoids more.
The other main one that I was more concerned about and I am sure you are too, is there is a good probability there will be a lot more PAIN.
Definitely a condition you would want to avoid
Assuming that for your work commitments you are forced to stand for long periods of time. Then the only suggestion that I can give in this situation is take a few days off work, until your hemorrhoids have settle down a little.
Alternatively, if you can't take time off work.
Just remember to sit at least fifteen minutes in the hour. This should help to relax the muscles and pressures around the anus area a little, thus avoiding major damage.
However, having said all of the above, I must also point out that if you have not got hemorrhoids of any kind, standing for a long time will not be one of the causes that will cause you hemorrhoids.
SIDEBAR: I guess that if you were without hemorrhoids, or have never had hemorrhoids in the past, you wouldn't be reading this page. Therefore the above statement is meaningless to all the readers.