types of hemorrhoids

External hemorrhoids are those that occur outside of the anal verge (the distal end of the anal canal). They are sometimes painful, and can be accompanied by swelling and irritation. Itching, although often thought to be a symptom from external hemorrhoids, is more commonly due to skin irritation.
If the vein ruptures and a blood clot develops, the hemorrhoid becomes a thrombosed hemorrhoid.
Internal hemorrhoids are those that occur inside the rectum. As this area lacks pain receptors, internal hemorrhoids are usually not painful and most people are not aware that they have them. Internal hemorrhoids, however, may bleed when irritated.
Untreated internal hemorrhoids can lead to two severe forms of hemorrhoids: prolapsed and strangulated hemorrhoids.
Prolapsed hemorrhoids are internal hemorrhoids that are so distended that they are pushed outside of the anus.
If the anal sphincter muscle goes into spasm and traps a prolapsed hemorrhoid outside of the anal opening, the supply of blood is cut off, and the hemorrhoid becomes a strangulated hemorrhoid.