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Endosonographic evaluation of anal sphincters in healthy children
Yasser Rehman1, Kjetil Juul Stensrud, Lars Mørkrid
1Faculty of Medicine, University of Oslo, Oslo, Norway.
Insights
Anal endosonography successfully visualized the internal and external anal sphincters in children. External anal sphincter thickness averaged 5.3 mm and increased with age, while internal anal sphincter measurements were more challenging.
Area of Science:
- Pediatric imaging
- Gastroenterology
- Anorectal physiology
Background:
- Accurate assessment of anal sphincter anatomy is crucial for diagnosing anorectal malformations and functional disorders in children.
- Endosonography offers a detailed view of pelvic floor structures, but its application in pediatric populations requires specific characterization.
Purpose of the Study:
- To delineate the endosonographic anatomy of the internal anal sphincter (IAS) and external anal sphincter (EAS) in healthy children.
- To assess the reliability of measuring IAS and EAS thickness using anal endosonography.
- To identify factors influencing sphincter visualization and measurement accuracy.
Main Methods:
- Anal endosonography was performed on 45 healthy children (median age 3.6 years) under general anesthesia using a 7-10 MHz rotating transducer.
- The IAS and EAS were independently evaluated by two observers to determine thickness and assess visualization quality.
- Interrater reliability for thickness measurements was calculated.
Main Results:
- Both IAS and EAS were visualized in all participants.
- Mean IAS thickness was 1.3 mm, and mean EAS thickness was 5.3 mm.
- EAS thickness measurements demonstrated excellent interrater reliability and a positive correlation with age; IAS measurements were more difficult, particularly in younger children (<3 years).
- Hyporeflective areas within the EAS were common and should not be mistaken for defects.
Conclusions:
- Anal endosonography is a viable tool for visualizing the IAS and EAS in pediatric patients.
- While EAS thickness can be reliably measured and correlates with age, precise IAS thickness assessment is challenging in young children.
- Recognizing variations in EAS reflectivity is important to avoid misinterpreting normal findings as pathology.
Purpose:
To describe the endosonographic anatomy of anal sphincters in healthy children and to evaluate the reproducibility of sphincter thickness measurements.
Methods:
Forty-five healthy children with median age of 3.6 years (range, 1.0-14.5 years) were studied while under general anesthesia for minor surgery. Anal endosonography was performed with a 7- to 10-MHz rotating transducer with a diameter of 19 mm. The internal anal sphincter (IAS) and the external anal sphincter (EAS) were assessed by 2 independent observers.
Results:
IAS and EAS were identified in all children. The mean thickness of IAS and EAS were 1.3 mm and 5.3 mm, respectively. Identification of the inner and outer border of IAS was difficult, especially in children younger than 3 years. The thickness of EAS was easier to assess, and the interrater reliability for EAS thickness measurements was excellent. EAS thickness was positively correlated with the children's age. Reflectivity varied within the EAS with frequent hyporeflective areas.
Conclusions:
Anal endosonography provided visualization of the IAS and EAS in children. Assessment of exact IAS thickness was difficult, especially in the youngest children. Mean EAS thickness was 5.3 mm, increasing with age. Hyporeflective areas of the intact EAS should not be misinterpreted as sphincter defects.
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