Anal Endoscophic Features of Normal Anus in Children

ABSTRACT

A recent application of anal endosonography has been popularized in adult patients to access staging of the rectal cancer and other lesions of the anorectum; however, this study has not been familiar to pediatric surgeons. We performed anal endosonography in 30 children without anorectal disease in order to obtain standard morphology of the anorectum. Internal anal sphincter (IAS) was clearly identified as a homogeneous hypoechoic circular band, extending caudally to a level just proximal to anal verge. The external anal sphincter (EAS) showed mixed echogenicity and different architecture along anal canal ; the EAS had U-shape in the upper canal and it showed circular pattern in the lower canal. In the upper canal of girls, the perineal body and the vagina were shown just anterior of the anal canal, which made the U shape of the EAS, whereas in male the sphincter tapered anteriorly into two arcs that met in the midline. The perineal body was prominent in female. Posteriorly, the anococcygeal ligament showed triangular shadow in both sex. The thickness of the IAS was measured in 3 directions, left, right and posterior, at 3 levels, upper, middle and lower of the anal canal. The average thiskness was 0.86-2.40mm between 6 and 18 months of age (Group 1), 0.88-3.20mm between 19 and 36 (Group 2), 1.07-2.20mm between 37 and 54 (Group 3) and 1.18-2.42mm more than 54-month-old (Group 4). The thickness was correlated wtih the age of the children only in the right upper(p=0.008) and the left middle portion (p=0.015). We could obtain standard morphologic features of normal anal canal in children with anal endosonography and we also believe that this technique is a safe and an effective procedure to evaluate anorectal lesions in children.