Imperforate Anus

What is it?

Also known as anorectal malformation, imperforate anus is an absence or incomplete anus.

Imperforate anus occurs 1 in 3000 live births.

Variations

There are several variations of the deformity and the severity depends upon where the large bowel ends within the body.
Imperforate anus can be divided into two groups.

1. Low Imperforate Anus

This is where the bowel stops slightly short of where the anus should be, or the anus is present but small or in the wrong
place. Treatment involves opening or moving the anus thus making a connection between the bowel and anus. The
operation is known as anoplasty or "cut back" and can be performed at birth.

2. High Imperforate Anus

A high imperforate anus is more complex. The bowel ends in a blind pouch or there may be an abnormal tract (fistula)
between the bowel and another part of the body. If a fistula is present, it is usually between the bowel and vagina in girls
and between the bowel and urethra in boys.

Signs and Symptoms

a.Babies back passage absent, very tiny or in the wrong place.

b.Distended tummy.

c.Unable to pass meconium (this is the dark stool newborn babies' pass within the first 24 hours

. of life). Or if a fistula present:

.1.Baby girl may pass meconium from the vagina.

.2.Baby boy may pass meconium from their urethra.

40-50% of babieswith an imperforate anus may have one or more associated problems, most commonly:

a.Genitourinary (renal tract)

b.Vertebral (spine)

c.Alimentary tract (gut)

d.Cardiac (heart)

e.Neural abnormalities, affecting the bowel and bladder (nerves to the bowel and

.bladder)

The baby will need various investigations to check for any associated problems.

Investigations

a.X-ray of babies' tummy (this will help to identify where the bowel ends and how

.big a gap there is between the bowel, and where the back passage should be).

b.X-ray of the spine.

c.Ultrasound of the kidneys.

d.Echocardiogram of the heart.

Treatment

Correction of a high imperforate anus is done in three stages:

Stage one - At birth, the baby will need to have a colostomy and mucous fistula formed.

Stage two - Once the baby is growing and putting on weight. (approximately 3 - 6

months old) A new anus will be made and the bowel pulled down and

connected to the anus.

Stage three - The colostomy and mucous fistula will be closed.

What is a Mucous Fistula

A mucous fistula is where a small piece of the non functioning part of the bowel is brought through a tiny opening on the
skin and then stitched in place on the tummy. Mucous is produced by the bowel for lubrication in order to aid the passage
of poo. The mucous fistula enables the mucus to be expelled from the non functioning bowel so that it does not become
stagnant. It is dark pink in colour, similar to the lining of the mouth, and is bud shaped. The mucous fistula only needs to
be covered by a small pad so that the mucous discharged does not mark the babies' clothes. The mucous fistula is not
painful as it does not have any nerve endings to cause pain.

Operation to create a new anus and to pull the bowel down to the anus

The surgeon will locate the end of the bowel and the abnormal tract (fistula) if present. The tract is usually between the
bowel and vagina in girls and bowel and urethra in boys. The tract is then closed with several stitches.

A small cut will be made, where the new anus is to be. The end of the bowel is then pulled down and through the small cut
on the bottom.

The blind end of the bowel is cut to make an opening and the edges are stitched to the skin to form an anus.

Once the babies new anus has had a chance to heal for about 7 days the new anus will require stretching using a dilator,
which come in several sizes. The purpose of stretching the new anus is so that when the colostomy is closed the anus will
be the right size for the baby to pass a normal stool. If it is too small the baby will become constipated and struggle to
push the poo out.

How is the Colostomy and Mucous Fistula closed

The surgeon will make a small cut on the babies' tummy, often he is able to use the old scar.

The surgeon will then join the colostomy (the functioning piece of the bowel) to the mucous fistula (the non functioning
piece of bowel, or bowel at present not in use). The two pieces are joined using several stitches. The tummy is then
stitched to close the wound. Usually dissolvable stitches are used so that they do not need to be removed.

Possible problems after the Colostomy is closed

Diarrhoea

Initially the poo will be loose and very frequent, this is quite normal. It may take several days or weeks before the bowel
settles down and the poo becomes less frequent and more formed.

Sore bottom

As the baby has not used their anus before, the skin around the anus will be delicate and very likely to get sore. This can
be overcome by prescribed creams.

Stricture

This is where an area of the bowel becomes narrow, making it difficult for the baby to pass a formed stool. This is treated
by further dilations or by stretching the stricture in theatre.

Constipation

The baby may have a tendency to be constipated one minute and have very loose poo the next. It is important that babies
bowels are opened daily to prevent constipation. Plenty of fluids and a high fibre diet will help.

Slow to potty train

Generally children are bowel trained before being dry. The opposite may be true of these babies'. To bowel train the child
may take longer than most children and will require persistence and patience.