Perianal hematoma

A perianal hematoma is a collection of blood under the surface of the skin at the edge of the anal opening.  Perianal hematomas are caused by a traumatic rupture of a small blood vessel in this area due to high pressures resulting from straining.  Many people with a perianal hematoma can recall lifting something heavy, moving house, carrying suitcases or children, severe coughing or straining with constipation shortly before they notice that there is something wrong in their anal area.  Similarly, perianal hematomas are commonly seen in people working out at gyms, lifting weights, etc.

The perianal hematoma presents as a painful lump at the edge of the anal opening (anal verge).  They can vary in size from a centimeter to the size of a golf ball, and are usually quite painful.  The pain will last for a week to ten days.  Patients take all sorts of over the counter medications for these but there is not much good evidence that anything helps.  A perianal hematoma has a natural course that it will follow pretty much regardless of what the patient does.  Eventually, the pain will lessen and stop, and the patient will be left with firm lump which will gradually shrink and disappear over the course of 3 months or so.

In some cases, it is best to have the hematoma excised by a physician.  If the hematoma is large and the physician sees it within the first 48 hours, excising it will lessen the pain and speed the entire course of healing.  If, however, the physician sees the patient later, when the hematoma is starting to settle and get less painful, there is not much point in excising it since the patient will be left with a wound that they have to manage, and that is not necessarily any advantage over having a resolving hematoma.  The other reason for excising a perianal hematoma is if the clot decides to erode through the overlying skin and bleed.  This usually occurs late, at about one to three weeks after the initial presentation.  In such cases, excising the hematoma will shorten this messy phase and leave a wound that will heal more quickly.

Perianal hematomas are often misdiagnosed as hemorrhoids or external hemorrhoids.  ‘External hemorrhoids’ is a poor term that probably should be abandoned.  It is pretty meaningless and usually refers to skin tags and such that do not develop hematomas.  Internal hemorrhoids can thrombose (clot), but when they do it is not due to a blown out vessel, but more likely to a vessel within the hemorrhoid that clots.  Thrombosed internal hemorrhoids are a much bigger deal than a perianal hematoma.  In a thrombosed internal hemorrhoid, the thrombosis may extend right up into the anal canal and low rectum.  Any physician foolishly trying to excise this under local anesthetic will quickly end up with a bloody mess and start wondering why he or she got out of bed that morning.  Such cases are usually referred on to a surgeon who will generally leave them alone to resolve on their own.

Perianal hematomas must be distinguished from true hemorrhoids, abscesses, and anal cancer, including the rare malignant melanoma that can occasionally start in this area and appear as a dark bluish lump or lumps.

Because perianal hematomas are usually the result of straining, they can recur.  Some patients who have had more than one may ask if they can have a ‘hemorrhoid operation’ to make sure they never get these ‘attacks of hemorrhoids’ again.  Of course, as noted above, a perianal hematoma is not a hemorrhoid at all, it is a trauma, a ruptured blood vessel.  The bad news is that there are probably a million blood vessels in the anal canal area and so preventative surgery would have to remove so much tissue that complications would be unacceptable.  In fact, patients will often say that the last one was on a different side.  So, in general, it does not make much sense to operate on anyone to prevent perianal hematomas.  The one exception to this is the patient who has repeated hematomas in the same area, in a spot where the skin or lower anal canal appears damaged or scarred.  In such cases there may be an underlying vascular injury or abnormality that predisposes the patient to recurrent hematomas and excising this area stands a good chance of preventing future occurrences.

© Pezim Clinic, Vancouver, British Columbia, Canada