Anorectal Malformations and Anterior Anus
Definitions
Anorectal malformation is a rare condition that affects 1 in 5000 babies. It is a condition where the anus is either in the wrong place, or absent, and the colon may connect to another organ instead. It is sometimes generically referred to as “Imperforate Anus” but this is actually just one rare type of anorectal malformation.
In girls, the commonest type of anorectal malformation is “Rectovestibular fistula” where the colon empties into the lower part of the vagina. Girls may also have a Cloaca, where the anus, vagina and bladder all join in to one abnormal opening on the perineum. This is rare and very complicated to manage.
In boys, the commonest type of Anorectal Malformation is “rectourethral fistula” where the colon joins the urethra at a variety of locations.
Both boys and girls may have “Anorectal Malformation without fistula” which is the same as Imperforate Anus. This accounts for 5% of all anorectal malformations, and is mostly seen co-existing in patients with Trisomy 21 (Down syndrome).
Both boys and girls may have “Recto-perineal fistula” where the colon opens on the skin of the perineum, but not in the correct position for an anus and through a very small hole.
An anus is considered to be normal if it meets three criteria;
It is in a normal position
It is a normal size
It has a sphincter muscle all the way around
Anterior Anus, on the other hand, is an anus that is a normal size, has a circumferential sphincter, but is sitting closer to the front of the perineum than is considered typical.
It can be challenging to confidently tell the difference between a perineal fistula and an anterior anus.
Anorectal malformations are almost always detected in the newborn period, as checking for a normal anus is an essential part of baby checks performed by doctors, nurses and midwives. You will see the “baby checklist” in your Red Book.
It is usually discovered at birth, and rarely detected during pregnancy.
GOALS OF CARE
Identify the anatomic type of anorectal malformation
Assess for associated abnormalities
Decide on the best time to correct the anorectal malformation
Create an anus that is in the appropriate position, of appropriate size, and with the best possible prospects for future continence.
OUTCOMES
All patients born with anorectal malformations will have challenges related to stooling.
Some patients will be prone to constipation, while others will have trouble with soiling. The type of anorectal malformation they are born does have some bearing on their future potential for continence.
The ultimate goal will always be to give the child the ability to have formed stools, and choose when and where they open their bowels, without pain, constipation, or soiling in between bowel actions. It can be a long journey to achieve this, but most patients get there one way or another.
DR ROB’S APPROACH
Dr Rob completed overseas fellowship training in Paediatric Colorectal Surgery, and worked in the Royal Children’s Hospital, Melbourne Colorectal and Pelvic Reconstruction Service during his senior training years, and is an expert in the management of anorectal malformations.
If your child is born with an anorectal malformation, Dr Rob will rely on physical examination findings and a few simple investigations to determine how best to manage your child from the newborn period.
Most children born with anorectal malformations will get a colostomy made within the next 24-48 hours, with the exception of girls with rectovestibular fistula and children with rectoperineal fistula. Girls with rectovestibular fistula often stool well through their vagina, provided the ‘fistula’ is of adequate size. Rectoperineal fistula in boys and girls can potentially be addressed in the newborn period through a single operation to move the fistula to the correct position and enlarge it.
If your child is born with anorectal malformation, and is referred to Dr Rob, he will transfer your baby, you, and all your future care to the Gold Coast University Hospital, as the management of children with this condition is multidisciplinary, and it is best to have your care in a tertiary centre where there is access to all the best available speciality medical, nursing and allied health services. Patients with Anorectal Malformations need lots of resources and appointments to get the best possible outcome.
Children with anterior anus are unlikely to ever need an operation, but may be prone to constipation.
POST OPERATIVE CARE AND RECOVERY
Post operatively your child will not be fed immediately. They will restart feeding once they are passing wind, or if they have a colostomy, when the colostomy has stool coming out of it. They will need a few days of intravenous antibiotics in hospital. The sutures will all dissolve and vanish. Dr Rob and the Surgical Nursing team will talk you through how to best look after your child's dressings and wounds.
Two weeks after the operation, Dr Rob will see you and your child again in clinic to check how their repair is healing, and measure the size of the reconstructed anus. He will teach you how to perform gentle dilatations for your child, which will help them to heal at an optimal calibre over the next few months.
You can find more helpful information here: Anorectal Malformations - Information for families
DR ROB McCUSKER
Gold Coast Children’s Surgeon
Dr Rob is dedicated to the highest quality of care and technical excellence for his patients.