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 3500-5000 babies are affected by ARM.

Signs of ARM

The signs of an ARM may depend on the type of ARM but may include the following:

  • Your baby has not had a poo by 2 days old
  • There is no hole (anal opening) for the poo to come out
  • The anal opening is in a different place to where it should be (more closer to the vagina or scrotum)
  • Poo might leak out from the penis or the area around the vagina
  • Poo may be mixed with the pee (urine)
  • Vomiting
  • Swelling (distension) of the tummy

Common types of ARM

Anal stenosis

Anal stenosis is when the anal opening is too small so the poo cannot be easily pushed through the hole and out of the body. Babies often are uncomfortable and straining when trying to pass a poo. Sometimes the baby is seen to pass a very thin poo.

Imperforate anus (ARM with no fistula)

Imperforate anus is when some babies are born without any opening on the skin for the poo to come out of the body. The rectum (the last part of the bowel) is closed off and does not create a hole in the skin for the poo to come out.

ARM with fistula

A fistula is a small tunnel of tissue that connects to parts of the body that are not usually connected.  An ARM with a fistula is when the rectum abnormally connects to the skin between where the hole should be and the vagina or the scrotum (perineum).  In boys, sometimes the rectum connects to the urethra (wee pipe) or bladder from the inside instead. In this case, sometimes boys are seen to pass poo from their penis.

 

Associated conditions

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

They can affect the:

V – Vertebral (spine)

A – Anus

C – Cardiac (heart)

T – Trachea (wind pipe)

E – (O)Esophagus (food pipe)

R- Renal (kidneys)

L – Limb (arm or leg)

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

Causes

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

Diagnosis

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.

Treatment

Without an anal opening in the correct place, your baby will have difficulty passing a poo and this can lead to a blockage in the bowel.  If left untreated, bowel blockage can lead to weaking of the bowel wall, causing a tear (perforation).

 

The treatment will depend on the type of ARM and if your baby has any associated health conditions listed above.

Babies with ARM are likely to need multiple surgeries.

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

 

Surgery

1st Operation – Temporary colostomy

A colostomy is an operation to make a temporary colostomy (bringing part of the colon out onto the tummy wall) so that your baby can pass poo into a bag.

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).

Sometimes further tests are done before the second operation, called a loopogram

Procedure – Loopogram

A loopogram is a special X-ray that give us more information about the type of ARM.

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.

2nd Operation – Posterior Saggital Anorectoplasty (PSARP)

A PSARP is a complex operation where a new anus is created. The operation will involve disconnecting the rectum from its surrounding structures and moving it from its abnormal position into a newly created anus

The surgery will usually take place when your baby is at least several months old but this timing can vary.

3rd Operation – Stoma reversal

Stoma reversal is the removal of the stoma and joining both ends of the stoma together.

It can take place once your baby has recovered and healed from the PSARP, 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.

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.

Risks

Potential risks following surgery include:

  • Bleeding
  • Infection
  • Breakdown of the wound
  • Damage to surrounding structures
  • Narrowing of the anal opening
  • Mucosal prolapse (protusion of the lining of the rectum)

 

Outlook

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.