What Causes Pain in the Back Passage?

Anal pain is pain felt at or around the anus, in the form of burning, stinging, a cutting sensation, pressure or throbbing.

The pain may occur only while opening the bowels, or it may continue for hours, or be unrelated to opening the bowels at all.

The commonest causes include anal fissure, complications of haemorrhoids, and perianal abscess. In anal pain that is long-standing or recurrent, however, other diseases may also need to be investigated.

Sharp pain while opening the bowels: anal fissure

An anal fissure is a small tear that forms in the anal canal.

It generally develops after hard and difficult stools. In some patients long-standing diarrhoea can also lead to a fissure.

Its typical symptoms are:

• A sharp, cutting or tearing pain while opening the bowels
• Burning and pain afterwards that can last minutes or hours
• A small amount of bright red blood on the lavatory paper

Putting off opening the bowels because of the pain can increase constipation and lead to a pain–constipation–fissure cycle.

Do haemorrhoids cause anal pain?

Haemorrhoids are not always painful.

Internal haemorrhoids in particular mostly present with painless bleeding.

If a clot forms within an external haemorrhoid, however, a thrombosed external haemorrhoid can develop. In this situation there may be severe pain of sudden onset and a tender swelling at the anal margin.

For this reason it is not right to make one’s own diagnosis along the lines of “I have anal pain, it must be my haemorrhoids”.

Throbbing, constant pain: could it be a perianal abscess?

Yes. This is an important condition.

A perianal abscess can form as a result of infection developing in the glands around the anus.

The pain is generally:

• Constant,
• Steadily increasing,
• Throbbing

in character.

Sitting and moving can increase the pain.

Swelling, redness, tenderness around the anus and fever may accompany it.

Where severe anal pain is accompanied by fever or swelling around the anus, medical assessment is required without delay.

An abscess does not always settle with antibiotics alone; in some patients it needs to be drained.

Can a perianal fistula cause pain?

A perianal fistula is an abnormal channel that develops between the anal canal and the surrounding skin.

It generally appears after a previous perianal abscess.

Patients may have:

• Recurrent swelling
• Pain
• Infected or foul-smelling discharge from around the anus
• Symptoms that settle from time to time and then start again

The pain easing once the discharge starts may not mean that the problem has gone away completely.

Can constipation cause anal pain?

Yes.

Hard and bulky stools can cause irritation in the anal canal and lead to an anal fissure in particular.

Correcting the constipation is therefore an important part of the treatment of many anal conditions.

Can diarrhoea also cause anal pain?

Frequent and watery stools can irritate the skin around the anus and cause burning and pain.

Long-standing diarrhoea can also contribute to the development of an anal fissure.

What other diseases can cause anal pain?

More rarely:

• Anal and perianal infections
• Perianal involvement in Crohn’s disease
• Skin diseases
• Injury
• Pain syndromes related to the pelvic floor muscles
• Certain tumours of the anal canal or rectum

can cause anal pain.

For this reason, pain that is long-standing or unexplained in particular should be examined.

What helps anal pain?

Treatment varies according to the cause of the pain.

In simple irritation or in conditions related to constipation, the following may bring relief in some patients:

• Preventing the stool from becoming hard
• Taking enough fibre and fluid
• Avoiding straining
• Not sitting on the lavatory for long periods
• Avoiding soaps and products that irritate the area
• Making use of warm sitz baths

In conditions such as an abscess, a thrombosed haemorrhoid or a chronic anal fissure, however, measures applied at home alone may not be enough.

When should a doctor be consulted?

Assessment is appropriate in the following situations:

• Severe anal pain
• Pain that does not settle within a few days
• Recurrent pain
• Swelling at the anus, or a lump that can be felt
• Bleeding from the back passage
• Infected or foul-smelling discharge
• A new change in bowel habit
• A sore that will not heal
• Unexplained weight loss

When is urgent assessment required?

Where the following are present together in particular:

Severe or steadily increasing anal pain + fever/shivering + swelling or redness around the anus

assessment is required without delay for the possibility of a perianal abscess.

In people whose immune system is suppressed, or who have diabetes, signs of infection should be assessed more carefully.

How is the cause of anal pain established?

In most patients the most important stage of the diagnosis is the history and a careful examination of the anal region.

Where necessary, investigations such as:

• Rectal examination
• Anoscopy
• Rectoscopy
• Endoanal ultrasound
• Pelvic MRI
• Colonoscopy

may be used.

Colonoscopy or MRI is not needed for every anal pain. The investigations are chosen according to the examination findings and the condition suspected.

Remember

Anal pain is not always haemorrhoids.

A sharp pain while opening the bowels suggests an anal fissure; a painful swelling of sudden onset suggests a thrombosed external haemorrhoid; and a constant, steadily increasing throbbing pain suggests a perianal abscess.

The first step in correct treatment is to establish the source of the pain.