A thrombosed hemorrhoid is a condition in which a blood clot forms inside a swollen vein in the anus.

External hemorrhoids form outside the anus. This type of hemorrhoid is more likely to develop a blood clot than an internal hemorrhoid, which develops within the anal canal.

Symptoms of a thrombosed hemorrhoid include:

• A very painful lump of soft tissue outside the anus. It may feel like a small, very tender pebble near the anus.
• Bright red blood on the toilet paper or on the stool.
• Constant pain that is made worse by passing hard stool.

Thrombosed hemorrhoids affect only the small veins near the skin surface (superficial veins). Unlike blood clots in the deep veins, blood clots in thrombosed hemorrhoids do not travel to the lungs or another part of the body and do not cause serious problems.

Home treatment may help relieve the symptoms of thrombosed hemorrhoids. Minor surgery is sometimes needed to remove a painful clot.