Magnetic resonance imaging in anterior ectopic anus

Area of Science:

• Pediatric Surgery
• Anorectal Malformations
• Medical Imaging

Background:

• The definition and diagnostic criteria for anterior ectopic anus (AEA) have varied, leading to ambiguity in prevalence and surgical indications.
• A recent proposal suggests AEA involves a normally appearing anal orifice anteriorly located, with the external anal sphincter (EAS) encompassing the anal canal.

Purpose of the Study:

• To evaluate the diagnostic utility of preoperative magnetic resonance imaging (MRI) for anterior ectopic anus (AEA).
• To correlate clinical findings and MRI-based sphincter distribution in infants with constipation and anteriorly located anal orifices.

Main Methods:

• Case series of four infants (three female, one male) presenting with constipation.
• Clinical assessment including measurement of the anal position index.
• Preoperative magnetic resonance imaging (MRI) to evaluate the distribution of the external anal sphincter (EAS).

Main Results:

• All four infants had an anteriorly located anal orifice of normal caliber and presented with constipation.
• Clinical anal position index was <0.34 in females and 0.44 in the male.
• Preoperative MRI demonstrated the EAS surrounding the entire anal canal circumference, including the ventral aspect, in all patients.

Conclusions:

• Preoperative MRI is recommended for diagnosing AEA by visualizing EAS distribution.
• This imaging approach can improve the understanding of AEA's association with constipation and surgical management outcomes.