Anorectal Anomaly

An anorectal anomaly is a disorder affecting the anus and the rectum, the last part of the digestive system. This page explains about anorectal anomaly, how it can be treated and what to expect when a child comes to Hospital.

After food has been digested it passes through the small bowel into the large bowel. The faeces (poo) is stored in the rectum until the muscles receive a message from the brain to empty the bowel. The faeces then pass out through the anus.

There are two types of anorectal anomaly – low anorectal anomaly and high anorectal anomaly.

• A low anorectal anomaly is where the anus is closed over, in a slightly different position or narrower than usual. There may also be a connecting passage to the skin called a fistula.
• A high anorectal anomaly is where the bowel has a closed end at a high level and does not connect with the anus, or it may connect with another part of the body, usually the bladder, urethra or vagina, through a fistula.

Girls can be affected by a very complex malformation where there is only one opening for the bladder, vagina and bowel. This is called ‘cloaca’ or ‘cloacal malformation’ and requires more specialist treatment than covered in this information.

Symptoms may vary according to the type of anorectal anomaly. The child will not be able to pass meconium – the dark faeces passed in the first few days of life – in the usual way. This can cause a swollen abdomen and vomiting.

If the child has an anorectal anomaly with a fistula, the faeces will be able to partially pass out of the body, near the vagina in girls or through the urethra in boys. As the faeces can only be partially removed from the body, this will not relieve the pressure in the abdomen, causing swelling and vomiting. Anorectal anomalies need to be diagnosed quickly as the baby can become very unwell in a short period of time.

An anorectal anomaly is usually diagnosed soon after birth, on examination, when the baby fails to pass meconium at all, or the meconium comes from a different place. Health care professionals use the passing of meconium as part of the standard newborn checking procedure.

The doctor may suggest tests to give a clearer picture of the type of anorectal anomaly and whether there is a fistula. These could include X-rays, ultrasound scans or rarely, MRI scans.

An anorectal anomaly happens when the bowel does not form properly while the baby is developing in the womb. We do not know exactly what causes this, but it is not due to anything that happened during pregnancy. Research has indicated some possible causes of anorectal anomaly, but these need further investigation.
An anorectal anomaly can be associated with other problems, but the doctor will examine the child closely to check if this is the case. About one in 3,000 babies are born with an anorectal anomaly.

The treatment depends on the type of anorectal anomaly. All types of anorectal anomaly will need an operation under general anaesthetic. In some cases, only one operation (anorectoplasty) will be needed, but most children may need a series of operations.

The first operation is to create a loop stoma (an artificial way of disposing of waste matter) usually in the days after birth. The second is a posterior sagittal anorectoplasty (PSARP) operation to join the bowel to a newly created anus. This usually happens when the child is a few months old and has gained weight.

The final stage is to close up the stoma. This happens when the child’s bowel and anus is working well a few months after the second operation.

The three operations are usually completed by the time the child is six to nine months old. In most cases, the surgeon operates on the child’s bottom, but occasionally an incision in the abdomen might be needed. The second operation referred to as a PSARP (posterior sagittal anorectoplasty). This describes the operation and the approach taken by the surgeons.

There are no alternatives to these operations as the child needs to be able to pass faeces to prevent it building up in the bowel.

Whichever operation is planned, you will receive information about how to prepare the child for the operation. The surgeon will explain the operation in detail, discuss any worries you may have and ask your permission for the operation by asking you to sign a consent form. An anaesthetist will also visit you to explain about anaesthetic in more detail. If the child has any medical problems, like allergies, please tell the doctors.

As the child cannot take oral fluids normally due to the blocked bowel, they will need a drip of fluids for a while before the operation. The child will also need a nasogastric tube, which is passed up the nose, down the foodpipe and into the stomach. This will drain off the stomach and bowel contents and vent any air which has built up, which will make the child more comfortable.

Anoplasty – the surgeon will open up the anus (if it was closed over), move the anus (if it was in a slightly different place to usual) or widen the anus (if it was narrower than usual).

Creation of loop stoma – the surgeon will bring the bowel to an artificial opening in your child’s abdomen (stoma).

Posterior sagittal anorectoplasty operation (also called PSARP) – the surgeon will create a new anus and then separate the bowel from the fistula (if there is one) and bring it down to join the newly created anus. They will then close up the fistula. If the fistula is very high, the surgeon may need to make an incision in the child’s abdomen to correct it. The child will continue to use the stoma so that the bowel and anus can rest and heal.

Closure of loop stoma – the surgeon will disconnect the bowel from the stoma and close it to form a fully working bowel.

All surgery carries a small risk of bleeding during or after the operation. There is a very small chance that the bowel could leak into the abdominal cavity. This could cause an infection called peritonitis, but we will give the child antibiotics to treat this, should it happen. If the child has a fistula, the urethra or vagina could be damaged when the bowel is disconnected but this is very rare.

There is also a chance the muscles used for bladder and bowel control could be damaged, but this is also very rare. In many cases, the muscles are already affected to some degree before the anomaly is repaired. Every anaesthetic carries a risk of complications, but this is very small. The anaesthetist is an experienced doctor who is trained to deal with any complications.

The child will come back to the ward to recover. We will keep the child as comfortable as possible, by giving regular pain-relieving medications. For the first few days, the pain relief will usually be given through a drip and then, when the child is more comfortable, in the form of medicines to be swallowed.

For the first few days, the child will need a drip of fluids until they feel like eating and drinking again. This will also allow the bowel to rest and start to heal. When the surgeon is happy that the area is healing, you can start to feed the child again, starting with small amounts, and increasing the amount as they tolerate it.

If the child has had a new anus created, in some cases, you may be asked to stretch (dilate) it using a probe called a dilator. In many cases, the surgeon will check the area and carry out the first dilatation while the child is under a short general anaesthetic. If further dilatation is needed, your surgeon will show you how to do this before you go home. You will need to start with a small size dilator and gradually increase the size until the anus is the right size. Most children do not require dilatation.

If the child has had the stoma created, the stoma nurse specialist/doctor will teach you how to look after it. We will make sure you feel confident before you go home.

You will be able to go home once the child is feeding well and starting to gain weight.

The child’s abdomen may feel sore for a while after the operation, but wearing loose clothes can help. The stitches used during the operation will dissolve on their own so there is no need to have them removed. If possible, keep the operation site clean and dry to let it heal properly. The surgeon will let you know when the child can have a bath, but do not soak the area until the operation site has settled down.

After all the operations, the child may have diarrhoea or constipation. This is an after-effect of the operation and we will discuss this with you at the follow up appointment. Occasionally some children need medicines to help with any bowel problems. After the operation, the child may have a very sore bottom. It is not a good idea to sit your baby upright or do anything that puts pressure on the healing area for several weeks after the operation. Whenever possible, leave the child’s bottom exposed to the air as this will help it heal too.

When the stoma has been closed and your child is in nappies, use nappy cream liberally to prevent nappy rash. Almost all babies develop nappy rash at some point after this operation, usually as a reaction to the bowel starting to work.

You will need to come back to hospital for an outpatient appointment about six weeks after each operation.

You should call your doctor or the ward if the child:

• has serious abdominal pain and/or diarrhoea
• has serious constipation

Seek urgent medical help if the child:

• vomits when feeding
• has a swollen stomach
• vomits green liquid
• is not gaining weight

The outlook for children with anorectal anomaly depends on the type of abnormality. Many children go on to lead normal lives. However, there are a couple of problems which you should know about should they arise in the future.

The child may need extra bowel training at a later stage to learn when and how to empty their bowels. They may also need some extra help in the form of enemas, washouts or medicines, but these will be explained to you if they are needed.

However, some children continue to have bowel problems for many years after the operations, but this depends on the original severity of the anorectal anomaly. If the child does not have full bowel control by the age of three years, please discuss this with the team at your next clinic appointment.

The child will need regular check-ups with your doctor at Hospital until they are well. Girls who have had an anorectal anomaly repair may be better having a caesarean section rather than vaginal childbirth. This will put less strain on the operation site and is less likely to cause problems in the future. Your daughter should discuss her previous medical history with her doctor when planning a pregnancy.

Before colorectal surgery

Order a set of Hegar dilators. You can search online to buy them or ask your surgeon where to get them.

Two weeks after colorectal surgery

You will have a clinic appointment with your child’s surgeon. During this visit, they will teach you how to dilate your child’s anus if he or she needs one. This is a very important appointment.

Once the surgeon has chosen the correct size of dilator needed to begin dilations, they will show you the proper technique. You will dilate the anus twice a day. Insert the dilator for 30 seconds twice in the morning and twice in the evening. Always do this before meals. You may need another person to hold your child while you do the dilations.

Each week, the size of the dilator should be increased to the next size. Your surgeon will tell you what dilator size is right for your child. The dilations may become painful when you increase the size. This can sometimes cause parents not to dilate because they are afraid to hurt their child. You will not harm your child during the dilation process. It is important to do dilations every day so that scar tissue does not form and cause strictures (narrowing) of the anus. Anal strictures are a major setback that can be easily avoided by following the dilation schedule as prescribed.

Rectal dilator size goals for different ages

• 1 to 4 months: #12
• 4 to 8 months: #13
• 8 to 12 months: #14
• 1 to 3 years: #15
• 3 to 12 years: #16
• 12 years and older: #17

Decreasing the frequency of dilations

Once your child has reached the desired dilator size and the dilator passes easily twice daily, you will begin to decrease the frequency of the dilations as follows:

• Once a day for a month
• Every other day for a month
• Every third day for a month
• Twice a week for a month
• Once a week for a month
• Once a month for three months