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Anal thrombosis

What is an Anal thrombosis?

Anal thromboses appear suddenly, often as painful knots around the anus, which are always harmless. The swelling is caused by a blood clot in a vein in the anus. Contrary to popular opinion anal thromboses are neither inflamed nor prolapsed haemorrhoids. One should therefore not attempt to push it back into the anus.

What are the causes?

Frequently thrombosis occurs acutely after sitting on cold surfaces, due to physical exertion (Sport) or in women during their period. Pregnancy, childbirth, pressure increases in the body during coughing, lifting or pressing, but also possibly certain foods (spices , alcohol) can cause thrombosis. Sometimes diarrhea triggers the formation of thrombosis. Presumably the presence of large haemorrhoids favors the formation of anal thromboses.

Who gets thrombosis?

Most middle-aged adults, men are affected slightly more often than women. In childhood anal thromboses are very rare.
What symptoms cause anal thromboses?
The most rapidly - within minutes to hours - swelling occurring on or in the anus is almost always associated with severe pain, sometimes associated with itching and burning. A thrombosis can reach chestnut size. The knots are bluish - red and feel rough to plump-elastic.

What research is needed?

The doctor uses his finger to examine the anus area. Occasionally, an instrumental examination is required.

Trend: Tendency
Even without treatment, the thrombosis regresses. The use of anti-rheumatic agents relieves the pain It may come to overlying skin ulceration by the pressure of the blood clot, so that the thrombus can empty out. This is usually accompanied by bleeding, but usually leads to an improvement of symptoms.


With little or already shrinking symptoms, no treatment is necessary. For moderate pain, the prescription of an anti-inflammatory drug may be useful. For highly painful thrombosis, the doctor can make a small incision under local anesthesia and the subsequent depletion of the thrombosis for rapid relief of symptoms. Sometimes the entire knot must be removed. These treatments are done outpatient.


A safe prophylaxis is not known. The treatment of haemorrhoids can be useful.