Imperforate anus

Imperforate anus
Classification and external resources
An X-ray showing Imperforate anus
ICD-10	Q42.3
ICD-9	751.2
OMIM	301800 207500
MedlinePlus	001147
eMedicine	ped/1171 ped/2923
MeSH	D001006

An imperforate anus or anal atresia is a birth defect in which the rectum is malformed. Its cause is unknown.

Features

There are several forms of imperforate anus:

• A low lesion, in which the colon remains close to the skin. In this case, there may be a stenosis (narrowing) of the anus, or the anus may be missing altogether, with the rectum ending in a blind pouch.
• A high lesion, in which the colon is higher up in the pelvis and there is a fistula connecting the rectum and the bladder, urethra or the vagina.
• A persistent cloaca (from the term cloaca, an analogous orifice in reptiles and amphibians), in which the rectum, vagina and urinary tract are joined into a single channel.

Imperforate anus is usually present along with other birth defects—spinal problems, heart problems, tracheoesophageal fistula, esophageal atresia, renal anomalies, and limb anomalies are among the possibilities.^[1]

Associated anomalies

Imperforate anus is associated with an increased incidence of some other specific anomalies as well, together being called the VACTERL association:

• V - Vertebral anomalies
• A - Anal atresia
• C - Cardiovascular anomalies
• T - Tracheoesophageal fistula
• E - Esophageal atresia
• R - Renal (Kidney) and/or radial anomalies
• L - Limb defects

Diagnosis

When an infant is born with an anorectal malformation, it is usually detected quickly as it is a very obvious defect. Doctors will then determine the type of birth defect the child was born with and whether or not there are any associated malformations. It is important to determine the presence of any associated defects during the newborn period in order to treat them early and avoid further sequelae. There are two main categories of anorectal malformations: those that require a protective colostomy and those that do not. The decision to open a colostomy is usually taken within the first 24 hours of birth.

Sonography can be used to determine the type of imperforate anus.^[2]

Treatment

Imperforate anus usually requires immediate surgery to open a passage for feces unless a fistula can be relied on until corrective surgery takes place. Depending on the severity of the imperforate, it is treated either with a perineal anoplasty^[3] or with a colostomy.

Prognosis

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With a high lesion, many children have problems controlling bowel function and most also become constipated. With a low lesion, children generally have good bowel control, but they may still become constipated.

For children who have a poor outcome for continence and constipation from the initial surgery, further surgery to better establish the angle between the anus and the rectum may improve continence and, for those with a large rectum, surgery to remove that dilated segment may significantly improve the bowel control for the patient. An antegrade enema mechanism can be established by joining the appendix to the skin (Malone stoma); however, establishing more normal anatomy is the priority.

Epidemiology

Imperforate anus has an estimated incidence of 1 in 5000 births.^[4][5] It affects boys and girls with similar frequency.^[6] However, imperforate anus will present as the low version 90% of the time in females and 50% of the time in males.

Imperforate anus is an occasional complication of sacrococcygeal teratoma.^[7]

References

External links

• Medline Plus Medical Encyclopedia: Imperforate anus