Anal atresia

Anal atresia (or imperforate anus) refers to a spectrum of anorectal abnormalities ranging from a membranous separation to complete absence of the anus.

Clinically there is no anal opening. There are frequent associations with other congenital abnormalities. It can be broadly be classified into high (supralevator) or low (infra levator) sub type depending on location of the atretic portion.

Radiographic features

Abdominal radiograph

• can be variable depending on the site of atresia (e.g high or low) , level of impaction with meconium and physiological effects such as straining. 
• may show multiple dilated bowel loops with with absence of rectal gas

Ultrasound

• may show bowel dilatation
• an infra coccygeal or transperineal approach may allow differentiation between a high or low subtype 4.

Associations

• VACTERL association
• caudal regression syndrome (has associated sacral agenesis and lower limb hypoplasia
• may have fistulous tracts with the
  • urethra
  • vagina
  • or have a single cloacal opening

See also

• oesophageal atresia
• duodenal atresia
• small bowel atresia

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