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Imperforate Anus

Last updated Oct. 9, 2018

Approved by: Maulik P. Purohit MD, MPH

Marc A Levitt, Alberto Peña

X-ray showing an individual with anal atresia; cross-table lateral film with the baby in prone position.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Anorectal Malformation (ARM)
  • Congenital Imperforate Anus
  • Pediatric Imperforate Anus

What is Imperforate Anus? (Definition/Background Information)

  • Imperforate Anus is a congenital birth defect characterized by abnormalities of the rectum and anus. In this disorder, the anal opening of a newborn child is either absent or blocked
  • Such a disorder in female infants would indicate that the rectum, bladder, and vagina, share one large opening, known as the cloaca

The abnormality may occur in various forms, such as:

  • The rectum could end in a blind pouch, which has no connection with the anus
  • The rectum may be connected to the urethra, bladder, and scrotum (in boys), or vagina (in girls), through an opening
  • The anus may either be absent, or narrowed (stricture)

Who gets Imperforate Anus? (Age and Sex Distribution)

  • An Imperforate Anus defect may form in any child. It is recognized at birth
  • There is no ethnic/racial predilection, or geographical restriction to the condition
  • The condition has an incidence of 1 in 5000 births, and generally boys are affected more than girls

What are the Risk Factors for Imperforate Anus? (Predisposing Factors)

The exact cause of Imperforate Anus abnormality is unknown, and so are the risk factors.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Imperforate Anus? (Etiology)

  • The exact cause of Imperforate Anus occurrence is still unknown
  • An abnormal development of the fetus (intrauterine fetal development) is the general cause for occurrence of this defect. This defect normally occurs during the fifth to seventh week of pregnancy
  • Congenital Imperforate Anus is also seen with other abnormalities of the rectum
  • Studies have shown that certain environmental factors and the use of some drugs during pregnancy, could lead to this defect. Nevertheless, these factors have not been proven with certainty

What are the Signs and Symptoms of Imperforate Anus?

Common signs and symptoms noticed in newborns suffering from Imperforate Anus include:

  • The newborns do not pass stools even after 24-48 hours of birth
  • Opening to the anus is either absent or is displaced to a different location. The anal opening, is located very close to the vaginal opening, in girls
  • The stool may pass out, either through the vagina, base of the penis, scrotum, or urethra
  • Swelling of the stomach is persistently visible
  • Constipation, abdominal pain, or bowel obstruction can occur
  • Presence of a fistula (an abnormal connection) between the rectum, reproductive organs, and the urethra, is observed

Some other associated abnormalities could include:

  • Kidney, urinary tract defects, spinal abnormalities, defects in the windpipe (bronchus and trachea defects) and in the food pipe (esophageal defects)
  • Deformities in the arms and legs
  • Down syndrome: A genetic disorder, in which an extra genetic material causes mental and physical developmental delay, in a child
  • Hirschsprung’s disease: A medical condition that is characterized by blockage occurring in the large intestine (megacolon)
  • Duodenal atresia: Underdevelopment of the first part of the small bowel (called duodenum)
  • Congenital heart diseases

How is Imperforate Anus Diagnosed?

A diagnosis for Imperforate Anus would involve:

  • A physical examination of the newborn, which is normally sufficient for the physician to confirm that the baby is born with an Imperforate Anus
  • Imaging tests that are conducted to further confirm the abnormality may include:
    • X-ray of the abdomen/belly, which will reveal the exact location of the defect. It can also reveal, if any other congenital spinal and sacral (lower back) deformities coexist
    • Abdominal and spinal ultrasound helps the physician diagnose, if any abnormalities exists in the abdomen and spinal cord
    • Echocardiogram: This may be conducted to detect any defects in the heart
    • Magnetic resonance imaging of the spine: Spinal cord defects may be discovered using this modality

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Imperforate Anus?

An Imperforate Anus is a serious and life-threatening medical condition, which requires immediate medical attention. If it is left unattended, it may lead to the following complications:

  • Infection of the urinary tract, which is likely to occur when stools pass through the tract
  • Major defects that affect the kidneys, urinary tract, spine, and windpipe
  • Deformities and defects affecting the limbs (arms and legs)
  • Down syndrome
  • Hirschsprung’s disease
  • Duodenal atresia
  • Congenital heart diseases

How is Imperforate Anus Treated?

Treatment measures for Congenital Imperforate Anus should be urgently considered, especially if comorbidities are present. These include:

  • Surgical intervention is the only method available to correct this abnormality. Sometimes, several surgical procedures are necessary, to rectify the defects
  • A temporary colostomy may be performed. Colostomy is a surgery that is done to connect the large intestine to the abdomen, in order to enable the stools to be collected in a bag
  • Medications may be administered to prevent urinary infections
  • A detailed investigation should be performed to check the newborn for other defects/abnormalities relating to the spine, genitals, urinary tract, kidneys, and esophagus
  • The newborn is fed intravenously, until the time oral feeding is permissible
  • After the surgery is performed, the child should be on a diet of foods, high in fiber and foods that can avoid constipation

How can Imperforate Anus be Prevented?

Imperforate Anus is a congenital birth defect. There are no means for prevention of the condition; it can only be rectified through appropriate surgical treatment.

Children who have undergone complicated colon surgery may have to regularize their bowel movements by following a bowel program, which include:

  • Eating fiber-rich food
  • Using stool softeners
  • Administration of enema, when required

What is the Prognosis of Imperforate Anus? (Outcomes/Resolutions)

  • The prognosis with Imperforate Anus, depends on the number and degrees of coexisting, congenital abnormalities (if any) present
  • Children with minor defects have an excellent prognosis
  • Proper diet control and avoidance of constipation, has a bearing on post-surgical outcome
  • Constipation can be a persistent and lifelong problem

Additional and Relevant Useful Information for Imperforate Anus:

Anorectal Malformations relate to a variety of defects of the lower intestines and urogenital region. In 50% of the cases, other accompanying defects/abnormalities that affect body regions, such as limbs, spine, heart, kidneys, etc. are observed.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Aug. 6, 2013
Last updated: Oct. 9, 2018