Changes in the length and diameter of the normal appendix throughout childhood

It has been proposed that the narrow diameter of the appendix is important in providing a 'safe zone' for commensal intestinal flora, while the length of the appendix can be variable. This study aimed to investigate the relationship between appendiceal length, diameter and age, in children under the age of eighteen years, to determine if the appendix changes in size with age.

The histological records of all cases of children undergoing appendicectomy at the Royal Children's Hospital (Melbourne) between 2009 and 2011 were retrospectively reviewed. Participants were excluded on the basis of histological evidence of acute inflammation, and data on the diameter and length of the appendix were collected from 210 children, aged zero to seventeen years.

Data were stratified by age for analysis into ≤ 3 years, >3 and ≤ 9, >9 and ≤ 13 and >13 years. Mean diameters per group were 3.7 (± 1.3), 6.3 (± 1.2), 6.7 (± 1.6) and 6.9 (± 1.6) millimetres respectively. Mean lengths per group were 39.7 (± 16.1), 66.3 (± 15.3), 63.7 (± 21.3) and 68.8 (± 18.2) millimetres. Both diameter and length were higher in the older age groups, compared with the ≤ 3 year olds (p < 0.001). A positive correlation was seen between age and appendix diameter (R = 0.5, p < 0.001) and length (R = 0.3, p=0.03) in the ≤ 3 group only. Mean diameter and length values did not differ significantly between groups aged > 3 years old.

This study showed that following an initial growth period during early infancy up to about 3 years, the appendix achieves its adult proportions and does not continue to grow throughout childhood.