An anal atresia (or imperforate anus) refers to a spectrum of anorectal abnormalities ranging from a membranous separation to complete absence of the anus.
The estimated incidence is at ~ 1 in 5000 births.
Clinically there is no anal opening. It can be broadly be classified into high (supralevator) or low (infra levator) sub type depending on location of the atretic portion.
Most cases tend to be sporadic with occasional familial forms
There are frequent associations with other congenital abnormalities.
- other atresias
- VACTERL association
- caudal regression syndrome (has associated sacral agenesis and lower limb hypoplasia
- may have fistulous tracts with the
- or have a single cloacal opening
Plain film / 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
- the anus may be seen as an echogenic spot at the level of the perineum and in an atresia this echogenic spot may be absent 4.
- may show bowel dilatation
- an infra coccygeal or transperineal approach may allow differentiation between a high or low sub-type 4.
- 1. Harris RD, Nyberg DA, Mack LA et-al. Anorectal atresia: prenatal sonographic diagnosis. AJR Am J Roentgenol. 1987;149 (2): 395-400. AJR Am J Roentgenol (abstract) - Pubmed citation
- 2. Berrocal T, Lamas M, Gutieérrez J et-al. Congenital anomalies of the small intestine, colon, and rectum. Radiographics. 19 (5): 1219-36. Radiographics (full text) - Pubmed citation
- 3. Han TI, Kim IO, Kim WS. Imperforate anus: US determination of the type with infracoccygeal approach. Radiology. 2003;228 (1): 226-9. doi:10.1148/radiol.2281011900 - Pubmed citation
- 4. Entezami M, Albig M, Knoll U et-al. Ultrasound Diagnosis of Fetal Anomalies. Thieme. (2003) ISBN:1588902129. Read it at Google Books - Find it at Amazon
Synonyms & Alternative Spellings
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|Atresia of the anus||✗|