Anorectal Malformation

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Condition: Anorectal Malformation (imperforate anus)

Overview (“What is it?”)

  • Definition:  This condition occurs when the rectum of the baby does not come all the way through the tissue of the bottom leaving no opening for the stool to be passed from the body. Depending on the severity of the condition, it is often classified as a low, intermediate of or a high anorectal malformation. It is also known as “imperforate anus".
  • Epidemiology:  Anorectal malformations (ARM) occurs in 1 baby in every 5,000 live births. It is equally seen in boys and girls.

Figure 1: Picture of a baby's bottom without an anal opening. Picture courtesy of MJArca 11/2016.

Signs and Symptoms (“What symptoms will my child have?”)

  • Early signs:  After the baby is born, an ARM is diagnosed as no opening for stool to be evacuated from the body or there is an abnormal position of the anus. Sometimes, ARM is noted when a baby does not stool within 24 hours or if a rectal thermometer cannot be inserted. If the anus is abnormally positioned, stool may come out of a different location—seen coming out of the vaginal area, or mixed in the urine.
  • Later signs/symptoms:  Most of the signs/symptoms occur after an attempt at surgical repair of the condition. One of the most common symptoms is constipation.

Diagnosis (“What tests are done to find out what my child has?”)

  • Labs and tests: Babies with ARM have higher risk of certain types of other abnormalities. It is important to find out if the baby has these abnormalities so nothing is missed that can impact the baby’s health moving forward. The most common abnormalities are grouped into the “VACTERL” association (named after the first letter of the most common anomalies).
    • V (spine):  Spine X-ray to look for abnormalities of the bones and ribs. Spine ultrasound or MRI may also be obtained.
    • Anus: Baby has high imperforate anus/cloaca
      • C (heart): An ultrasound of the heart (echocardiogram) is needed to check for problems such as abnormal holes, problems with valves, etc.
      • Tracheo-Esophageal fistula (TEF): Abnormal connection between airway (trachea) and esophagus (tube that connects mouth to stomach) and a blind-ending esophagus in neck. 
      • Renal (kidney): Ultrasound of kidneys to look for abnormalities
      • Limbs (arms and legs): Examine arms and legs for deformity. Arms most common place for abnormal bones.
  • An abdominal film/X-ray, abdominal ultrasound and pelvic magnetic resonance (MRI) scan are often done to delineate the extent of the imperforate anus
  • Conditions that mimic this condition: Babies can have variations in their rectal, genital and urinary anatomy. In girls, the rectum may join with the vagina and urethra to form what is known as "cloaca."

Treatment (“What will be done to make my child better?”)

  • Medicine:  Medications are not helpful before surgical repair. Since air and stool in the intestine are not being emptied properly because of the anal problem, the baby’s belly can get swollen. The baby is not fed and occasionally, a tube is passed from the mouth into the stomach to remove air and fluid to keep the abdomen from becoming distended before surgery.
  • Surgery:  The type of surgery that the baby gets first depends on many factors including the size of the baby and other conditions that s/he may have.  The designation of “low” “intermediate” or “high” ARM is given depending on the location of the abnormal opening in relation to the muscle that controls stooling or the sphincter muscle.
    • Babies who have a low ARM and who are otherwise healthy may undergo a definitive repair performed soon after birth. In this repair, the end of the anus is matched with the center location of the sphincter muscle. Depending on how complicated the operation is, the baby may need a temporary colostomy to protect the surgical site from stool as the wounds are healing.
    • In babies with an intermediate or high imperforate ARM, or if the baby has conditions that would make it unsafe to undergo a definitive repair (such as complex heart condition, very small size), a temporary colostomy (bringing part of the intestine out through the abdominal wall) may be performed to allow for growth which helps increase the success of the procedure. The baby’s stool comes out of this stoma.
Photo of stoma and mucus fistula.
Figure 2. Photo of stoma and mucus fistula (encircled in purple ink). Photo courtesy of MJArca 11/2016.
    • Preoperative preparation:  Your baby will be kept from eating until the surgery is performed. He/she will be given nutrition through an IV (intravenous catheter) until then. 
    • Postoperative care:  Many times, babies will require a period of anal dilation to decrease the risk of developing a stricture or narrowing where the anal opening is relocated. This can be done at home for a number of months until healing has occurred and the risk of post-operative stricture has decreased.
    • Risks/Benefits:
      • Risks:  Infection or breakdown of the wound, bleeding, damage to surrounding structures may occur during any surgery.
      • Benefits:  The infant requires a way to evacuate stool effectively, whether relocation of the anal canal in ARM or a colostomy.

Home Care (“What do I need to do once my child goes home?”)

  • Diet:  Normal
  • Activity:  Normal
  • Wound care:  Cleaning the surgical incision after going home is important, as long periods of stool on the skin and incision can lead to wound breakdown in the immediate post-operative period. Use of barrier creams such as zinc oxide are helpful to prevent this skin breakdown.
  • Medicines:  Often times a medication such as senna or Mira-Lax is given to help develop good bowel habits.
  • What to call the doctor for:  Any fevers or redness around the incision. Also call your doctor if your child goes more than two days without having a bowel movement or has vomiting, fevers or abdominal pain.
  • Follow-up care:  You should plan to see your surgeon within two weeks of having the surgery performed and will likely have several visits a year for the first few years of life to make sure your child is able to pass stool without difficulties.

Long-Term Outcomes (“Are there future conditions to worry about?”)

  • Patients with low ARM have excellent results in terms of continence (able to control bowel movements). They have a very high risk of having constipation for the rest of their lives. Children with intermediate and high ARM have lower success rates, as the severity of the anatomic and neurologic abnormalities are increased in these patients. These children may have more problems with soiling of stool and poor sphincter control. It may take several years to determine the final outcome of the surgical procedure.
  • Specialized diets and medications may be needed to help your child have regular bowel movements and to reduce the chance of incontinence or soiling. In intermediate to high ARM, further studies and operations may be required in the future to create the best situation in terms of stool control.

Updated: 11/2016
Author: Michael B. Ishitani, MD
Editors: Patricia Lange, MD; Marjorie J. Arca, MD