Conditions Affecting the Anal Canal

A wide array of conditions may affect the anal canal, but generally present with either pain, bleeding or feeling a lump around the anus. The following is a summary of the most common and important of these conditions;


Haemorrhoids or piles are enlarged, bulging blood vessels in and about the anus and lower rectum. Haemorrhoids are very common and many people will not even know that they have them. Generally however they cause bright red bleeding which is seen on the toilet paper and occasionally in the toilet following opening your bowels. Patients may also notice itching around the anus. Sometimes patients notice a lump around the anus which may need to be “pushed back” or may return to the anal canal on their own following a bowel movement. These are known as “prolaped” haemorrhoids. Some prolapsed haemorroids are unable to be pushed back and these may become extremely painful, however haemorrhoids are generally not painful. Although having piles does not lead to any increased risk of developing cancer, the symptoms may also be seen in patients with colorectal cancer and should be evaluated by a doctor.

What causes haemorrhoids?
The exact cause is not known, however a number of factors are thought to contribute. The fact that humans walk upright increases the pressure on the rectal blood vessels which causes them to bulge out.  Other factors include: aging, chronic constipation, pregnancy, family history, straining during bowel movements and spending long periods of time on the toilet (i.e. reading).

What is the best treatment?
The simplest treatment is to increase the amount of fibre (e.g. fruits, vegetables, breads and cereals) and fluids in the diet, avoid straining or spending a long time on the toilet. This avoids constipation and reduces the pressure in the anal canal. If haemorrhoids are particularly troubling a variety of procedures can be performed as an outpatient.

Rubber band ligation
For larger haemorrhoids placing a small rubber band around the base is an effective treatment. The band cuts off the blood supply to the pile. The pile and band fall off in a few days leaving behind a small wound that heals in a week or so. When the bands are applied some patients may feel some discomfort at the time and for a few days after. Bands may need to be re-applied on several occasions for symptoms to resolve completely.

Injection sclerotherapy
Injection of the haemorrhoid with phenol works in a similar way to rubber band ligation with the injection causing the pile to shrivel. Again this may be mildly uncomfortable and may need to be repeated.

Removing the pile surgically is reserved for severe haemorrhoids that are too big to be treated with the above techniques. Although after the procedure patients may have marked pain and discomfort the operation is safe, highly effective at curing piles and can usually be performed as a day case. Laxatives and pain relief are routinely prescribed, however patients should expect to take some time from usual activities following their operation.

Stapled haemorrhoidopexy
Recently a technique using a special staple gun to remove internal haemorrhoids has been developed. It is successful at treating internal piles but does not remove any portion outside the anal canal if present. It is more painful than outpatient techniques but less painful than a traditional haemorrhoidectomy.

Haemorrhoidal artery ligation (THD or HALO)
A relatively new technique in which the arteries that supply the haemorrhoids are identified in the anal canal by use of a special probe (Doppler) and obliterated by stitches has become widespread. This technique is relatively painless and has shown some good early success rates in eradicating piles.

Perianal haematoma

Patients may suddenly develop a small painful lump at the edge of the anus. This often happens after passing stool and represents an ruptured blood vessel at the edge of the anal canal. It is not sinister and often resolves itself, often by discharging a small amount of blood as the clot bursts. Avoiding constipation and using simple painkillers is often all that is required. Sitting in warm water for about 10 minutes may also help and the pain usually subsides in a few days. If the pain is severe or persistent the blood clot can be evacuated using a small incision under local anaesthesia as an outpatient to provide relief.

Peri-anal abscess

Patients with an abscess around the anal canal present with severe pain often associated with fever and feeling generally unwell. An abscess forms when one of the glands which surround the anal canal becomes blocked and infected with bacteria. Some groups of patients such as those with Crohn’s disease are more prone to develop these abscesses. In those with diabetes or who have a reduced immunity peri-anal abscesses may be very dangerous and should be treated immediately. The treatment for these abscesses is by surgery. A small incision is made over them and the pus evacuated. Due to the sensitivity of the area and need to be sure all infected material has been removed they should be performed under general anaesthetic in hospital. Often the cavity may be large and will require regular dressing by the district or practice nurse until it has healed properly. Although antibiotics are sometimes tried, they work poorly in this condition since they do not penetrate the inside of the abscess cavity. Following healing of the abscess around half of those treated will go on to develop a fistula.


An anal fistula is a connection, or tunnel, between the inside of the anal canal and the skin around it. It is the result of a previous abscess which develops when the anal glands become blocked and subsequently infected. Fistulas present about 4-6 weeks after an abscess has been treated but may become obvious months or years later. A fistula leads to persistent discharge of pus or fluid around the anus leading to soiling of underwear and skin irritation. Occasionally the fistula may appear to have healed only for a recurrent abscess to form. Patients with Crohn’s disease are particularly prone to the development of anal fistulas.

What is the treatment for a fistula?
Surgery is the treatment of choice to cure an anal fistula. Dealing with most fistulas is straightforward involving simply opening the fistula tract (laying open) and joining the internal opening to the external opening. This wound is then allowed to heal slowly and requires regular dressing changes by a district or practice nurse. Some fistulas however, are more difficult to treat. Since many fistulas pass from the anal canal through the muscles that control bowel continence (the anal sphincters) and out to the skin, laying the fistula open may lead to the division of part of of these muscles. If the fistula passes through the sphincters near the top of the anal canal (a high fistula) a large quantity of muscle would be divided with a risk of developing subsequent incontinence to stool. In these complex cases there are a variety of techniques available including the use of setons (a suture passed through the fistula), advancement flaps and even artificial plugs or glues made from collagen. It is important to discuss these risks with your surgeon.

Anal Fissure

An anal fissure is a small tear in the skin that lines the anus. They present with pain on defecation and bright fresh rectal bleeding usually o the toilet paper. The pain associated with a fissure may be so severe that patients avoid going to the bathroom, this leads to constipation and even more pain. Often patients will not allow their doctor to examine their anus since the pain is unbearable, this is almost diagnostic of a fissure. Fissures typically occur following trauma to the lining of the anal canal, this is commonly due to passing hard dry stool such as with constipation. They may also be associated with inflammatory conditions such as Crohn’s disease. Fissures are divided into acute, which are of new onset, and chronic which have been present for over 6 weeks or are recurrent. Chronic fissures are usually associated with a small skin tag at the anal margin known as a sentinel pile.

How are fissures treated?
Acute fissures are likely to resolve without the need for surgery. Simple measures to avoid constipation such as increasing the amount of fiber in the diet, increasing liquid intake, using stool softeners are often sufficient. If a chronic fissure develops these simple measures should be instigated but the addition medical treatments should be insitgated. Applying a pea sized lump of 2% diltiazem cream to the anal canal twice a day is a simple measure which causes the anal sphincter muscle to relax and leads to fissure healing in over 50% of people. Although some favour the use of GTN ointment, which has the same effect as diltiazem, this may not be tolerated by some people due to the development of headaches. If creams fail, injecting Botox (botulinum toxin) directly into the sphincter muscle can be attempted and may lead to healing in up to 75% of patients. If these treatments fail consideration should be given to surgery. This usually consists of an operation to cut a small portion of the internal anal sphincter muscle (a lateral sphincterotomy). This is a highly effective treatment for a fissure with complete healing occuring in a few weeks. There is however, a small risk of minor incontinence following this procedure and the benefits and risks should be discussed with your surgeon.

Anal Cancer

Anal cancers usually arise from the skin cells (squamous cells) around the anal opening and are known as squamous cell carcinomas. Anal cancer is relatively uncommon accounting for 1% of all gastrointestinal cancers with colorectal cancer being arround 40 times more common. Some patients develop pre-cancerous cells, which require regular surveillance, these are known as carcinoma-in-situ. The symptoms of anal cancer are similar to those of many anal canal lesions such as itching, bleeding, pain, feeling a lump, an alteration in bowel habit and even swollen glands in the groin. Since the anal canal is an area easily accessible to doctors, making an early diagnosis should be possible with rectal examination and simple biopsy under anaesthetic. Risk factors for developing anal cancer include; age, the presence of anal warts and infection with the human papiloma virus (HPV), anal sex, HIV infection, smoking, impaired immunity and previous pelvic irradiation.

How are anal cancers treated?
Following diagnosis patients undergo a series of tests such as an MRI scan of the anal canal and a CT scan of the whole body to asses the extent of the cancer. The mainstay of treatment is a combination of chemotherapy and radiotherapy which is highly effective in most cases. Surgery is seldom used as a first line treatment, unless the cancer is very small and can be completely removed without damaging underlying structures. Surgical intervention may be used to create a stoma whilst chemotherapy and radiotherapy is proceeding to reduce the risk of diarrhoea, incontinence and pain on defecation. This is usually a temporary stoma and is reversed when the treatment is completed and the cancer eradicated. Occasionally the cancer is not completely destroyed by the combined treatment or recurrs, in these cases “salvage” surgery is indicated to remove the entire rectum and anal canal leaving the patient with a permanent colostomy (abdomino-perineal resection). Thankfully such procedures are undertaken rarely these days and high cure rates are widely reported with chemo and radiotherapy treatments alone.