What is Anorectal Malformation?

An anorectal malformation is a congenital disorder in which the anus (bottom hole) does not develop at the normal location.

How is anorectal malformation detected?

In boys, most cases of ARM are obvious. The anus is absent when you look at the bottom, the baby has not passed meconium (dark poo) and the tummy is distended. The child may pass meconium from his urethra (urinary opening). Sometimes, the child passes meconium and stools from a tiny abnormal opening located little upwardsthan the normal location (anal stenosis or recto-perineal fistula). This subtle abnormality may go undetected in early infancy and will present as constipation later.

In girls, the meconium may pass from abnormal opening little upwards than normal location (anterior ectopic anus or recto-perineal fistula) or form the area just next to vagina (recto vestibular fistula). Girls may pass meconium/stools through a single opening in perineum from which urine and stools both come out (cloaca). Rarely, girls may not pass meconium and present with distension of tummy.

How common are anorectal malformations?

Anorectal malformations are uncommon. The incidence is 1 in 3000 to 4000 newborns.

Can there be any other problem?

Approximately one third of the ARM cases are associated with problems in other organs like heart, kidney, vertebrae, bones and rarely other organ systems.

What are the types of anorectal malformations in boys?

ARMs in boys are broadly classified into subgroups depending on the location of rectum/anus;

  1. Low variety – the rectum is just short of opening up at bottom (covered with skin only) or it is opening little upwards as a tiny hole
  2. Intermediate & High variety – the rectum is higher and it communicates with the urethra or urinary bladder through a very narrow connection called a fistula (recto urethral fistula, recto vesical fistula).

What are the tests to be done?

Doctor will ask for blood investigations, x-rays, sonography of abdomen and echocardiography. Before the second stage, the doctor will ask for a loopogram and MCU (special type of x-rays) to know the correct type of ARM. These x-rays will help him plan the pull through operation.

What is the treatment of anorectal malformation in boys?

Treatment of anorectal malformation is operation. The type of the operation is determined by the type of malformation, associated other problems and overall health of the child.

In boys with low type of malformation anoplasty or a pull through procedure (PSARP) is done to create the new anus. In boys with high variety of malformation the traditional 3 stage surgical treatment is recommended. However, a single stage pull through procedure can be offered in select cases.

The first stage is creation of stoma on the belly of the child within first few days of birth (emergency life-saving surgery). The second stage is done at around three months of age and a new anal opening is created at the bottom. The third stage is closure of the colostomy. After the third stage the child passes stools from the new anal opening created at the bottom. The current recommendation is to complete all three stages of surgery within first 6 months.

What is a “stoma”?

The artificial opening created on the belly from which stools come out directly on belly is called a ‘stoma’. When large intestine (colon) is brought out it is called colostomy and when small intestine (ileum) is brought out it is called ileostomy.

What is anal dilation?

After the second operation it is important to make sure that the new anus does not narrow while it is healing. It will therefore require dilatations (stretching). The doctor will start dilatation after 2 to 3 weeks of second surgery when the surgical site is completely healed. A well lubricated metal/plastic rod is inserted in to the newly formed anus to prevent it from narrowing down. The doctor will demonstrate and teach the parents how to dilate the newly formed anus. The size of dilator will be increased as and when required.

6. What are the types of anorectal malformations in girls?

ARMs in girls are largely classified into subgroups depending on the location of rectum/anus;

  1. Low variety – anterior ectopic anus. The rectum opens little upwards than its normal location
  2. Intermediate and high variety – recto vestibular fistula, recto vaginal fistula and cloaca. When the rectum opens near the opening of the vagina it is called recto vestibular fistula (most common ARM in girls) and when it opens deep inside the vagina it is called recto vaginal fistula. When urinary, vaginal and rectal openings are opening in a common single channel, it is called cloaca. It is a complex malformation.

What is the treatment of ARM in girls?

Most of the ARMs in girls can be corrected with a single surgery (PSARP or ASARP). Rare malformations like cloaca and high recto vaginal fistula require a three stage approach like boys.

What is the future outcome of ARM?

Overall, the outcome of ARMs is good. Children with ARMs will need long term follow up in a surgical clinic. A few children with mild ARMs have a normal bowel function. They are continent and not constipated. They do not require any long term medicines or intervention. However, many children may require medicines to improve constipation and/or continence. A few may require additional surgery to improve bowel function.