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Anal dilatation in children

Patient information A-Z

What is anal dilatation?

Anal dilatation involves passing a dilator into your child’s anal opening. The anal dilator is left there for a few seconds and then removed. Anal dilators are available in many different sizes. The appropriate size for your child will be assessed by a member of your child’s surgical team.

Anal dilators

Why have I been advised that my child needs anal dilatation?

Children may require anal dilatation for any of the following reasons:

  • As a treatment for anal stenosis - Stenosis means narrowing. Anal stenosis refers to a narrowing of the anal opening (‘bum hole’) which makes it difficult for stool (‘poo’) to pass through easily. Treatment of anal stenosis involves gently stretching the anal opening (anal dilatation). Anal dilatation is typically undertaken twice a day for children with anal stenosis. Each week a slightly larger lubricated dilator is used to gradually stretch the anus until it reaches normal size; then the frequency of anal dilatation is reduced and, after a few months is usually not required any longer. In some cases surgery is needed in addition to anal dilatation to ensure an opening of adequate size.
  • After anoplasty surgery - Children born with an ‘ano-rectal malformation’ (that is, born without an anal opening) undergo surgery to create a new anus. At the time of surgery the bowel is pulled down and a cut is made on your child’s anus. The edges of the bowel are stitched to the skin to form a new anus (such surgery is complex and exact details will be given to you by your child’s surgeon). Once your baby’s new anus has had a chance to heal (usually 7 to 14 days) your surgeon may advise that the anus is gently stretched (dilated). This will help to prevent the stitches from causing a narrowing (stitches can cause a narrowing by pulling together too tightly during the healing process) or to help increase the size of the anus.
  • After pull through operations for Hirschsprung’s Disease - Children with Hirschsprung’s disease do not have the correct nerve cells in part of their bowel. This prevents them from being able to pass poo (‘stool’) properly. An operation is performed to remove the section of bowel which does not have the ganglion (nerve) cells within it. The end of the bowel is joined up just inside the anus. Once the bowel has had a chance to heal (after seven days) your child may require anal dilatation. This will help prevent narrowing and ensure poo can pass easily.

Who will show me how to carry out anal dilatation?

A member of your child’s paediatric surgical team will carry out the first anal dilatation to decide which size dilator to use, how far it needs to be inserted and how frequently the dilatations need to be carried out.

You will then be taught by the paediatric surgery nurse specialists how to perform the anal dilatations. You will either be taught whilst your child is on one of our children’s wards or you will need to return to the outpatient clinic to be taught.

What equipment is needed?

  • anal dilator (appropriate size)
  • lubricating jelly

How do I perform anal dilatations?

Some parents and carers find that they can undertake anal dilatation for their child on their own. Others find that having two people present is helpful.

  • Collect equipment.
  • Wash hands.
  • Ensure you have the correct size dilator.
  • Ensure your child is comfortable on a flat surface.
  • Remove the nappy
  • Position your child as you have been shown (normally the same position as changing a nappy).
  • Apply the lubricating jelly to the anal dilator.
  • Hold the dilator between your fingers and thumb (like holding a pen). Gently rest the dilator on the outside of your child’s anus to allow your child to get used to the cold sensation from the lubricating jelly.
  • Gently push the dilator to insert it into your child’s anus (approx ______ cms or ________ inches).
  • Once inside the anus hold the dilator in place for a few seconds and then remove completely.
  • The dilator should feel snug inside the anus. It should not be forced. If you have difficulty inserting the size of dilator advised, it can be helpful to insert a smaller sized dilator first, immediately followed by the one of planned size.
  • When the procedure is finished, clean your child’s bottom.
  • Wash the dilator in warm soapy water (it does not need to be sterilised)
  • Wash your hands.

Is anal dilatation uncomfortable?

The lubricating jelly is cold and this can cause babies and children to become upset. Some parents and children find anal dilatations upsetting but when carried out regularly this becomes less stressful and will become a matter of routine. Many babies and children are never upset by having anal dilatation performed.

If your child has had recent anal or rectal surgery, pain relief may be required before anal dilatations are performed.

What are the complications of anal dilatation?


Your child may experience a small amount of bleeding from their anus following anal dilatation. They may have some bleeding with their next poo (the size of a two pence piece). Such bleeding is quite common but if you notice a significant amount of fresh bleeding, please seek advice from your GP or paediatric surgical team.


Your child may experience some pain with the first few dilatations and when increasing the dilator to larger sizes.

If your child experiences any pain we advise that you give Paracetamol (‘Calpol’). Please follow the instructions on the bottle. If there is an increase in pain, then please seek advice from your GP or paediatric surgical team.

Insertion difficulties

If at any time you have difficulty with inserting the anal dilator do not force it. Retry again later the same day. If required, try a smaller sized dilator and then increase back up to the required size. If the difficulty continues, contact a member of the paediatric surgical team

Frequently asked questions

Where do I get the anal dilators?

The dilators will be supplied to you by the hospital.

How often will I need to carry out the anal dilatation?

Anal dilatation is normally carried out once or twice a day to start with, depending on your child’s needs. Frequency is then gradually reduced over time. This will be discussed with you at your follow-up appointments.

How long will I need to carry out the anal dilatations out for?

This will depend on your child’s condition. It is based on the individual’s needs. The paediatric surgical team will be able to advise you on this.

When will the size of the dilator be increased?

Your child will have a target sized dilator. The size of the dilator will be gradually increased (normally weekly) until the target size is met. This normally means weekly visits to the hospital as size increases are carried out by the Paediatric Surgical team.

Follow- up

Your surgeon will inform you of any follow up. A letter will be sent in the post with the specific date and time.

For further information or queries please contact:

Clinical Nurse Specialist:

Tel: 01223 586973


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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151