Normal appendix: is there any significant difference in the maximal mural thickness at US between pediatric and adult populations?

Purpose: To evaluate the normal maximal mural thickness (MMT) of the appendix in asymptomatic subjects and determine whether any significant difference in MMT exists between pediatric and adult populations.

Materials And Methods: The MMT of 187 appendices in asymptomatic subjects was measured at sustained-compression ultrasonography (US). The measured MMTs were categorized into three groups according to patient age (39 young children [including infants] aged 1-6 years, 79 older children and adolescents aged 7-15 years, 69 adolescents and adults aged 16-82 years), and the relationships between categoric variables were analyzed by using analysis of variance and the parametric Scheffé test.

Results: The mean MMTs in the young children, older children and adolescent, and adolescent and adult groups were 1.9 mm +/- 0.4 (SD), 2.0 mm +/- 0.5, and 2.1 mm +/- 0.5, respectively. The corresponding ranges of normal MMT were 1.1-2.8, 1.0-2.8, and 1.2-3.0 mm, respectively. No significant difference in normal appendix MMT was observed between the young children group and the older children and adolescent group (P =.2) or between the older children and adolescent group and the adolescent and adult group (P =.639). The difference in MMT between the young children group and the adolescent and adult group was marginally significant (P =.042).

Conclusion: Although adoption of age-related MMT criteria does not seem warranted because it would necessitate measurement precision below 0.5 mm, which is not possible to achieve consistently in daily practice, data indicate that in children aged 6 years or younger, an appendiceal mural thickness of less than 3 mm should be regarded as normal.