Anorectal malformations (ARM)

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What are anorectal malformations?

Anorectal malformations (ARM) are a group of conditions some babies are born with that affect the bottom (anus and rectum).

About 1 in 5000 babies are affected by ARM.

Signs of ARM

  • Your baby has not had a poo by 2 days old
  • There is no hole for the poo to come out, or the hole is in a different place
  • Poo might leak out of the vagina or penis
  • Poo might leak out of a different place
  • Poo may be mixed with the pee (urine)
  • Vomiting
  • Swelling (distension) of the tummy

Types of ARM

Anal stenosis

Anal stenosis is when the anus is too small or in the wrong location so the poo cannot be pushed through the hole and out of the body.

Imperforate anus

Imperforate anus is when some babies are born without an opening for poo to come out of the body.

Anal fistulas

A fistula is a small tunnel of tissue that grows.  It connects 2 places that are not usually connected.  An anal fistula is when the fistula forms between the rectum and the skin near the anus.  It means poo leaks out of the bowel into the hole in the skin.

It can cause:

  • infections near the anus
  • weakening of the bowel wall
  • a hole or tear
  • urinary tract infections


The causes of ARM are not known.

It is not caused by something parents have done or not done.

The chance of ARM increases if your baby has:

  • a close relative with the condition
  • other genetic conditions


A doctor can diagnose ARM by looking at your baby’s bottom after they are born.

Your baby will then have more tests to find out exactly how ARM is affecting them.


All babies with ARM will need surgery.

While your baby waits for their operation they are likely to need:

  • a nasogastric tube (NG tube) – a tube is placed in your baby’s nose and passed into their stomach.  This will empty the stomach to prevent vomiting and swelling
  • intravenous fluids (drip) – your baby will be put on a drip so they can receive fluids and antibiotics


Quick explanation that there are complex + non complex ARM? [e.g. The type of surgery that babies have will depend on how complex their ARM is]

[Mild/non-complex ARM?]

Your baby’s surgical team and anaesthetist will explain each operation to you in detail.

You should ask them any questions you have.  It might help to write down the questions or worries you have before you speak to them.


This operation is where the anal opening is made the correct size for your baby and placed in the correct position.  Usually your baby will begin to feed and poo shortly after the operation.

The operation takes place under general anaesthetic.

Complex ARM

Babies with complex ARM are likely to need 3 operations and 1 procedure called a loopogram.

1st Operation – Temporary colostomy

A colostomy is an operation to move the end of the colon (large bowel) to the surface of the tummy.

The new opening in the tummy is called a stoma and this will be where the poo comes out.

A bag is put over the stoma and will collect the poo.

Most babies will be able to start feeding within a few days of having the colostomy.

Parents will be taught how to care for their baby’s colostomy so they can look after it while at home. The colostomy will stay in place for several months (until the third operation).

Procedure – Loopogram

A loopogram is used to look for problems with the bowel.

A dye that shows up on X-rays (contrast dye) is inserted into the stoma and X-rays are taken as the dye passes through the bowel.

Doctors can look at the X-rays to work out how the ARM is orientated.  This helps plan the second operation.

2nd Operation – Anorectoplasty

Anorectoplasty is a complex operation where a new anus is created, and the rectum and bowel is moved and connected to it.

The surgery will usually take place when your baby is at least a few months old but this timing can vary.  This operation is open surgery which takes place under general anaesthetic.

3rd Operation – Stoma reversal

Stoma reversal is the removal of the stoma.

It can take place once your baby has recovered and healed from the anorectoplasty, and the anus is large enough for your baby to poo.

After the reversal, your baby will be able to poo through their anus into a nappy in the usual way.

Caring for the skin around the bottom is important as it can be very sensitive.  We will show you how to do this.


Each baby is different.

Some babies will grow up to have normal bowel function but most will need long term medication for constipation (laxatives) or help with their continence.  A small number of children will need a permanent colostomy (stoma).

Surgery will give each baby the best chance of having as much function as possible.

We review all our babies with ARM in clinic until they are around 16 years old.

Associated conditions

You may hear doctors talking about ‘VACTERL’ conditions.  These are conditions that ARM is often associated with.

They can affect the:

  • spine
  • bottom
  • heart
  • wind pipe (trachea)
  • food pipe (oesophagus)
  • kidneys
  • arms or legs

Your baby is likely to have tests to check for any problems with these body parts.