External Haemorrhoidal Thrombosis: what it is, causes, symptoms and treatments

• External haemorrhoidal thrombosis is a complication of simple haemorrhoids, which can cause severe pain.
• The colour left in the anal area by external haemorrhoidal thrombosis is purplish and blackish.
• Relief of an external haemorrhoidal thrombosis can be done conservatively, although in many cases surgery is required.

Everyone has haemorrhoidal veins, but this does not mean that everyone suffers from the condition commonly known as "piles". Haemorrhoids are found in the anal canal and are made up of arteries, veins, smooth muscle and other tissues. 

The function of this structure is to provide a more effective closure of the anus and to help maintain pressure in the anal canal when at rest.

The pathology known as haemorrhoids occurs when the entire haemorrhoidal structure is displaced downwards and protrudes outwards. These haemorrhoids can be external or internal depending on their location.

• External haemorrhoids: These are usually indicated as those found in the last third of the anus or on the outside, covered by skin. They are usually internal haemorrhoids that come out of the anus.
• Internal haemorrhoids: These are found in the upper two thirds of the anal canal and are covered by the mucosa secreted by the intestine.

With regard to the symptoms caused by haemorrhoids, we can divide them into chronic and acute:

• Chronic symptoms of haemorrhoids: The main symptoms are usually bleeding during defecation or cleansing, the prolapse of the haemorrhoid mass outwards, reaching a point where it is no longer possible to reintroduce it, as well as the discomfort that all this causes in the patient's daily life.
• Acute symptoms of haemorrhoids: It is in these cases that we find external haemorrhoidal thrombosis and possible thrombosed haemorrhoidal prolapse towards the outside. Haemorrhoidal thrombosis is mainly due to a complication that causes severe pain. In the following we will focus on this problem in more detail.

Pain is not a common symptom of haemorrhoids, although there is a possibility of a blood clot forming in the haemorrhoid, which can cause episodes of severe pain.

Haemorrhoidal thrombosis is a complication of simple haemorrhoids, which causes an acute picture of intense pain. In the case of external haemorrhoidal thrombosis, it is seen as a purplish, blackish, indurated (hardened) area at the margin of the anus, which is very painful to the touch.

One of the main problems with external haemorrhoids is when, due to sphincter contraction, it becomes trapped on the outside, becoming hard, painful and unable to shrink.

The main symptom of external haemorrhoidal thrombosis is pain, followed by hardening as mentioned above.

It appears as a bulge in the anal area, which in addition to the pain it causes, involves a lifting of the skin and the appearance of a purplish blue or blackish colour, as we mentioned. It is sometimes possible that the pressure it exerts on the skin causes an ulcer and blood comes out.

The onset of pain occurs mainly during defecation, when sitting, walking or simply touching the area. This situation may prevent the patient from sitting, make defecation difficult due to the intense pain and is commonly referred to as a "piles attack".

Diagnosis of external haemorrhoidal thrombosis at the doctor's office is very simple and can be made by direct inspection of the area by the specialist.

Most commonly, haemorrhoidal thrombosis resolves spontaneously after a few days, with all the symptoms gradually diminishing, reintroducing itself into the anal canal and decreasing in size.

Despite this, in a few cases external haemorrhoidal thrombosis can lead to necrosis and ulceration, which usually only affects the prolapsed portion of the haemorrhoid, although sometimes it can occur in the entire haemorrhoidal plexus and even in the rectal wall, leading to a serious infection in the pelvic area.

Thrombosed haemorrhoidal prolapse, on the other hand, is due to thrombosis of the vessels of third or fourth degree internal haemorrhoids, which prolapse and cannot be reduced due to oedema and are intensely painful. 

Ulceration and necrosis may occur during the course of the disease.

When the patient suddenly develops a nodule, a lump, in the anus, he/she may have external haemorrhoidal thrombosis. In this case, the pain is continuous and very intense, intensifying even more during defecation and when sitting.

In most cases, the condition resolves spontaneously, so conservative treatment may be an appropriate approach. This consists of:

• Use of ice or cold compresses can help minimise discomfort.
• Sitz baths
• Analgesics, to control pain.
• Stool softeners, to facilitate defecation.

In these cases, the thrombus is gradually reabsorbed over the next few weeks, although the pain is relieved after 2-3 days and the lump is relieved over the next 7-10 days.

Manual reduction of the thrombosed haemorrhoid is also possible. Analgesia is commonly used for this procedure due to the pain experienced by the patient during reintroduction, and is usually performed in the doctor's office.

After this reintroduction, the pressure exerted by the anal sphincter is minimised and normal venous circulation in the haemorrhoidal veins is restored.

If the pain is very severe, surgical evacuation of the clot is recommended. This is an outpatient procedure, with local or brief general anaesthesia.

It is important to note that before proceeding with surgery it is necessary to assess the seriousness of the problem, in case there are other problems in the anal area, especially internal haemorrhoidal thrombosis.

Surgery to evacuate the clot within 48-72 hours of the onset of external haemorrhoidal thrombosis usually results in rapid relief of symptoms. This is recommended for patients who are in severe pain or who experience ulceration or rupture within the first 72 hours.

An elliptical incision is usually made in the skin of the haemorrhoidal thrombosis, preferably radial to the sphincter. Bleeding often accompanies the incision and can be controlled with pressure or electrocoagulation. The wound may be left open or closed in the first instance. In patients with severe haemorrhoidal disease, with pain severe and accompanied by anxiety, the procedure may be performed under general anaesthesia.

During the postoperative period, a compressive bandage is applied to control bleeding, which the patient should not remove until a couple of hours after the procedure.

Bleeding is occasionally observed. Sitz baths and painkillers are recommended for the first 7 to 10 days after the procedure.

Complications are generally rare and mild. Bleeding occurs with the passage of hard faeces. Local infections are rare, probably due to the rich vascular network in the anal area. Skin tags and scarring may also occur but are uncommon.

In most patients who are treated conservatively the resolution of symptoms is faster, but the final recovery period is longer, with higher recurrence rates compared to patients who were treated by surgical intervention.

Although treatment of thrombosed external haemorrhoids is simple and quick, it is advisable to consider performing a haemorrhoidectomy to prevent the appearance of new thrombosed haemorrhoids and to avoid painful complications.