Anal atresia
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Anal atresia (or , or imperforate anus,) refers refers to a spectrum of anorectal abnormalities ranging from a membranous separation to complete absence of the anus.
Epidemiology
The estimated incidence is 1 in 5000 live births.
Pathology
Clinically there is no anal opening. ItSubtypes can be broadly be classified into two broad categories: high (supralevator) or low (infralevator) subtype, depending on the location of the atretic portion.
Genetics
Most cases tend to beare sporadic, with occasional familial forms
Associations
There are frequent associations with other congenital abnormalities.
- other atresias
- VACTERL association
-
caudal regression syndrome
(has: associated sacral agenesis and lower limb hypoplasia -
may havefistulous tractswithto the- urethra
- or vagina
- may be present or may have a single cloacal opening
Radiographic features
Abdominal radiograph
- can be variable depending on the site of atresia
(e.g(i.e. high or low), level ofimpaction withmeconium impaction and physiological effects such as straining - may show multiple dilated bowel loops with
withan absence of rectal gas
Invertogram
A coin/metal piece is placed over the expected anus and the baby is turned upside down (for a minimum 3 minutes).
DistanceThe distance of gas the gas bubble in the rectum from the metal piece is noted:
- >2 cm
:denotes high type - <2 cm
:denotes low type
Fluoroscopy: contrast study
- to detect a recto-urinary,
recto-vaginalrectovaginal, or rectoperineal fistula - the fistula is considered low (below the levator ani plane) if it is below the
pubooccygealpubococcygeal line (PCL) andconsideredhighfistulaif abovethe PCLit
Ultrasound
- 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 coccygealinfracoccygeal or transperineal approach may allow differentiation betweenahighorand lowsubtypesubtypes 4
Complications
See also
-<p><strong>Anal atresia</strong> (or <strong>imperforate anus</strong>) refers to a spectrum of anorectal abnormalities ranging from a membranous separation to complete absence of the anus.</p><h4>Epidemiology</h4><p>The estimated incidence is 1 in 5000 births.</p><h4>Pathology</h4><p>Clinically there is no anal opening. It can be broadly be classified into high (supralevator) or low (infralevator) subtype depending on location of the atretic portion.</p><h5>Genetics</h5><p>Most cases tend to be sporadic with occasional familial forms</p><h5>Associations</h5><p>There are frequent associations with other congenital abnormalities.</p><ul>- +<p><strong>Anal atresia</strong>, or <strong>imperforate anus,</strong> refers to a spectrum of anorectal abnormalities ranging from a membranous separation to complete absence of the anus.</p><h4>Epidemiology</h4><p>The estimated incidence is 1 in 5000 live births.</p><h4>Pathology</h4><p>Clinically there is no anal opening. Subtypes can be classified into two broad categories: high (supralevator) or low (infralevator), depending on the location of the atretic portion.</p><h5>Genetics</h5><p>Most cases are sporadic, with occasional familial forms</p><h5>Associations</h5><p>There are frequent associations with other congenital abnormalities.</p><ul>
-<a href="/articles/caudal-regression-syndrome">caudal regression syndrome</a> (has associated sacral agenesis and lower limb hypoplasia</li>-<li>may have fistulous tracts with the<ul>-<li>urethra</li>-<li>vagina</li>-<li>or have a single cloacal opening</li>-</ul>-</li>- +<a href="/articles/caudal-regression-syndrome">caudal regression syndrome</a>: associated sacral agenesis and lower limb hypoplasia</li>
- +<li>fistulous tracts to the urethra or vagina may be present or may have a single cloacal opening</li>
-<li>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</li>-<li>may show multiple dilated bowel loops with with absence of rectal gas</li>-</ul><h6>Invertogram</h6><p>A coin/metal piece is placed over the expected anus and the baby is turned upside down (for a minimum 3 minutes).</p><p>Distance of gas bubble in rectum from the metal piece is noted:</p><ul>-<li>>2 cm: denotes high type</li>-<li><2 cm: denotes low type</li>- +<li>can be variable depending on the site of atresia (i.e. high or low), level of meconium impaction and physiological effects such as straining</li>
- +<li>may show multiple dilated bowel loops with an absence of rectal gas</li>
- +</ul><h6>Invertogram</h6><p>A coin/metal piece is placed over the expected anus and the baby is turned upside down (for a minimum 3 minutes).</p><p>The distance of the gas bubble in the rectum from the metal piece is noted:</p><ul>
- +<li>>2 cm denotes high type</li>
- +<li><2 cm denotes low type</li>
-<li>to detect recto-urinary, recto-vaginal or rectoperineal fistula</li>-<li>the fistula is considered low (below levator ani plane) if it is below the pubooccygeal line (PCL) and considered high fistula if above the PCL</li>- +<li>to detect a recto-urinary, rectovaginal, or rectoperineal fistula</li>
- +<li>the fistula is considered low (below the levator ani plane) if it is below the pubococcygeal line (PCL) and high if above it</li>
-<li>an infra coccygeal or transperineal approach may allow differentiation between a high or low subtype <sup>4</sup>- +<li>an infracoccygeal or transperineal approach may allow differentiation between high and low subtypes <sup>4</sup>
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