Anorectal malformation (ARM) refers to an abnormality in the formation of the rectum or anus of a newborn.
These babies often present with no opening to their bottom end at birth.
When I give lectures to medical students on this topic, I will jokingly comment, “No one is perfect, we are all born with a crack, so these kids are perfect!”
To explain the cause of Anorectal Malformation, I will refer to the evolution of the species.
- Reptiles and birds have a common channel for faeces and urinary excrement from which these are expelled.
- The next time you get bird droppings on your car, note that the white, more liquid substance is the urinary concentrate, while the darker, more solid substance that corrodes paintwork and is mixed into the urinary concentrate, is the faeces.
- Similarly, the household lizard produces dark, neatly compacted faeces, and “delicately” decorated on top, is a white spot, which is the urinary concentrate.
- In mammals, however, the urinary system and the ano-rectal passage is separated and functions independently. Failure of this separation process before the child is born results in ARM in babies.
Hence, the “poo” and “wee” pipes remain abnormally connected in these kids.
The most common abnormality in a girl child with ARM is when the rectum opens into the entrance of the vagina, with no other opening on the bottom.
In a boy child, the commonest form is when the rectum opens into the urethra (urinary tube connecting the bladder to the tip of the penis), close to the prostate gland and again with no other discernible opening on the bottom.
The connection between the rectum and the above-mentioned structures are often small, and hence, the baby will not be able to open his or her bowels, which will subsequently be obstructed.
It is imperative that a paediatric surgeon create a stoma (bowel opening into a bag on the abdomen) to prevent bowel obstruction.
Once a stoma is formed, the child can feed and grow until definitive surgery can be planned to construct a new opening for the anus, usually after a few months.
Smelly people don’t make many friends, so most of us try to remain socially continent of faeces, unless a mishap occurs after eating dodgy food at the mamak stall the night before.
Our mechanism of continence is a voluntary control of our anal sphincter, which is shut tightly most of the time until one relaxes it when safely positioned over the toilet bowl, ready to defecate.
In a child with ARM, these sphincter muscles surround the anal canal and are usually still present in the correct place despite the rectum connecting to other structures.
The definitive surgery would involve disconnecting the rectum from whatever it’s attached to, and “re-plumb” it through the sphincter muscle.Dr. Nada Sudhakaran
The surgery would hope to achieve a good calibre new anus, which is centrally placed within the sphincter muscle and can function to maintain faecal continence.
As you can imagine, the surgery itself is a delicate process of trying to preserve the precious sphincter muscles and carefully placing the new anus in the precise location.
A paediatric surgeon should perform this complex surgery, as it is crucial that surgery is done correctly the first time round.
Once the reconstructive work is done, the stoma can then be closed, so that the “new bottom” can then be used.
The surgery may involve a larger incision near where the new anus is to be located, and some surgeons offer keyhole surgery for boys, which means smaller incisions.
Most children do well in the long term. However, some may be constipated, requiring long term use of laxatives to help them with their bowel opening.
Some children may have the opposite problem of incontinence, often dirtying their underpants.
This may become a social hindrance. However, there are bowel management programs, which are successful in maintaining social continence, so that these kids are not rejected by society.
The key point is that this condition requires specialised treatment.
Paediatric surgery is a highly specialised field. The outcomes for such conditions are better if treated appropriately at the right time, the right place and by the right person.
Dr Nada Sudhakaran is a paediatric surgeon. This article is courtesy of the Malaysian Association of Paediatric Surgery. This article was published on The Star