Some hemorrhoids are serious, causing excruciating pain and making the process of eliminating solid waste an ardous task. Many however, are just a pain in the, well you understand. Some hemorrhoids cannot be seen or felt and in some cases, those can be the most dangerous of all.
Generally, hemorrhoids are not life threatening. They can be rather irritating and can certainly diminish the quality of life. In very rare cases they can facilitate internal infections which can cause blood poisoning, which can be fatal. Unfortunately, these cases are among the most difficult to detect.
Basically, hemorrhoids are divided into two categories: Internal and External. External hemorrhoids are the ones most complained about. You can usually see them quite readily and they causing itching, swelling and pain. Often they will also bleed. These hemorrhoids develop on the exterior of the anus, thus the denotation: external. Internal hemorrhiods develop within the rectal or anal canal. They cannot be seen; they do not itch or hurt and are therefore much more difficult to detect. Unfortunately, internal hemorrhoids can often cause more damage than external hemorrhoids.
External hemorrhoids develop below the dentate line of the anus and can be seen. Sometimes they can develop into rather large blood clots. They look like large dark, usually purple, bulbs. When this happens they are termed thrombosed and so are called thrombosed hemorrhoids. Sometimes the blood in the clots dries, creating a hard cyst like bulb (though they are not cysts). Sometimes they may burst and cause bleeding. These are called bleeding hemorrhoids.
Internal hemorrhoids develop above the dentate line of the anus and cannot be seen. Often people afflicted with internal hemorrhoids are unaware of them, especially in the early stages of development. They can however cause considerable bleeding. If you notice that you are bleeding from your anus, it may be that you have developed internal hemorrhoids.
If left untreated internal hemorrhoids can develop into prolapsed hemorrhoids. These are cases where the bulbous vein within the anal canal stretches and protrudes all the way through the anus. Prolapsed internal hemorrhoids can be seen on the exterior of the anus. Some less severe prolapsed internal hemorrhoids may retract back into the anus after defication. In more severe cases, they will continue to protrude through the anus indefinitely.