Perianal hematomas or perianal thromboses occur when blood pools inside the tissues surrounding the anus, outside of the blood vessels. The hematomas vary in size depending on the cause and severity and can be very painful. A perianal hematoma forms when the small blood vessels in the anus break due to injury or excessive pressure on the anus. Some perianal hematomas resolve on their own, while others require specialist treatment.


Perianal hematomas present as a collection of blood, usually blue or deep purple, under the skin around the anus. A bump or bulge ranging from a tiny lump to a large swelling the size of a tennis ball. The growths are usually painful and can result in the passing of bloody stools if the hematoma is actively bleeding.

Perianal hematomas

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Common Causes

Perianal hematomas are caused by an action or injury that puts a strain on the blood vessels around the anus. Constipation, and the action of straining to pass stool, can cause these blood vessels to rupture. Pressure on the anus during pregnancy and childbirth can also lead to the condition. Lifting heavy weights, severe coughing, certain medical procedures and sitting still for a long time can also put undue pressure on the anus.

common causes Perianal hematoma

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The only way for a doctor to diagnose a perianal hematoma is by conducting a physical examination. However, the exam is not usually invasive because perianal hematomas form on the outside of the anus and are easy to see. It is rare a physician will require an internal examination or colonoscopy to identify a perianal hematoma.

diagnosing Perianal hematoma

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Perianal Hematoma vs. External Hemorrhoid

It is common to confuse a perianal hematoma with an external hemorrhoid because the two conditions look quite similar, and share some causes and symptoms. However, there are key differences between the two. Hemorrhoids are swollen blood vessels that occur inside the anus. Sometimes, a hemorrhoid can protrude out of the anus, creating the appearance of a perianal hematoma. However, it is possible for a hemorrhoid to move back inside. Perianal hematomas, on the other hand, always occur externally.

external Perianal hematoma

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Home Treatment

Once a doctor diagnoses a perianal hematoma, he or she may recommend non-invasive home treatments that will allow the hematoma to heal on its own. However, this may not be possible if the hematoma is very large or is not healing properly. A sitz bath, which involves soaking the anal area in a warm (not hot) shallow bath containing no detergents, can encourage healing. Cool packs, increased fiber intake, and removing pressure when sitting with a circular pillow designed for hemorrhoids can also help to reduce pain and speed healing time.

treating Perianal hematoma

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Perianal Hematoma Drainage

If the perianal hematoma is huge or has formed a blood clot, the doctor may recommend drainage. This short, surgical procedure requires the surgeon to numb the anal area using a local anesthetic. A small incision in the hematoma allows accumulated blood and fluid to drain out, reducing swelling. If there is a blood clot inside the hematoma, the doctor will remove it through the incision.

drainage Perianal hematoma

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Drainage Recovery

Usually, doctors will not stitch incisions from drainage surgeries, but rather leave them open for faster healing. For this reason, it is important to keep the anus clean and dry while it heals to prevent infection and further inflammation. The patient should start to feel relief within a few days, but it is best to avoid strenuous physical exertion until the hematoma has healed completely.

recovering from Perianal hematoma

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Risk Factors

Pregnant women and people who live a very sedentary lifestyle are at a higher risk of developing perianal hematomas because more pressure is placed on the blood vessels around the anus during pregnancy and when sitting for long periods. People who eat a diet low in fiber also have a higher risk -- insufficient fiber intake leads to constipation, which can cause perianal hematomas.

risk factors Perianal hematoma

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High amounts of bacteria exist near the anus, so surgeons must take great care during surgeries in this region, taking every possible step to ensure the area is clean during and after the procedure. If bacteria do enter the wound, an infection is highly likely. While antibiotics can often eradicate infections, in more severe instances a patient may need further surgery to remove infected tissue.

complications with Perianal hematoma

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Some cases of perianal hematomas are not preventable, but any measure that helps prevent constipation will also reduce the risk of developing these growths. Eating a high-fiber diet rich in fruits and vegetables and keeping well-hydrated are effective, as well. If constipation does occur, treating it early can help stop perianal hematomas or hemorrhoids from forming. Reducing the amount of time sitting down, or taking breaks from sitting to move around at frequent intervals, can reduce pressure on the blood vessels of the anus, thus preventing ruptures.

prevention Perianal hematoma

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