Evaluation of sacral hiatus changes in children using ultrasound

Abstract

Background and objectives: The intercornual distance in the sacral hiatus has yet to be studied precisely in children. This age-stratified, observational study aimed to clarify the changes in sacral hiatus dimensions and to quantify the correlations between the intercornual distance of the sacral hiatus and age, height, weight, and head circumference by using real-time ultrasonography.

Methods: The patients were stratified into three groups: neonates and infants, toddlers, and schoolchildren. In the operating room, the ultrasonic probe was placed at the sacral cornua to obtain a transverse view of the sacral hiatus, and the intercornual distance was measured three times in millimetres.

Results: The study included a total of 156 patients. The mean ± SD (95%CI) of intercornual distance in neonates and infants (<12 months) was 11.58 ± 1.79 (11.11-12.04) mm, 13.29 ± 1.97 (12.71-13.86) mm in toddlers (13-36 months), and 13.36 ± 2.49 (12.64-14.08) mm in schoolchildren (>36 months).The mean values of neonates and infants were different from those of toddlers and schoolchildren (p < 0.001), but it was similar between toddlers and schoolchildren (p > 0.05, 95 % CI mean difference -1.10 to 0.95).Intercornual distance was correlated with age, height, weight, and head circumference before one year of age (Spearman's R values > 0.7), but there was no correlation thereafter (Spearman's p value > 0.05).

Conclusion: In the first year after birth, the intercornual distance increases rapidly with body growth; after one year of age, the sacral hiatus dimension changes significantly. Ultrasound is superior for assessing the gradually ossified cartilage components in older children.

Keywords: Intercornual distance; Paediatric caudal block; Sacral hiatus dimension; Ultrasound.

Fig. 1

Transverse ultrasonography of the sacral hiatus. “A” a 7-day-old neonate, “B” a 4-year-old child, “↑” the white one-way arrow points to the cornua,“↔” the white double-sided arrow presents the intercornual distance between the two cornua.

Fig. 2

The distributions of intercornual distance (mm) based on patient age, height, weight, and head circumference. Abbreviations: cm, centimetre; kg, kilogram; mm, millimeter.

Fig. 3

The ANOVA between Group I, Group II, and Group III. The H-shape represents the mean with 95 % confidence intervals. Abbreviations: ANOVA, analysis of variance. p < 0.05 was considered significant.

Fig. 4

The simple regression analysis between intercornual distance and patient age, weight, height, and head circumference in group I. The full line represents simple regression, and the dashed curves represents the 95 % confidence intervals.