Ultrasound Evaluation of the Sacral Area and Comparison of Sacral Interspinous and Hiatal Approach for Caudal Block in Children

Abstract

The S2-3 approach can be applied as a useful fallback method to the conventional landmark approach in children, especially in those older than 36 months who present with difficult identification of the sacral hiatus.

The Myth of the Equiangular Triangle for Identification of Sacral Hiatus in Children Disproved by Ultrasonography

“…1 To identify the sacral hiatus, palpation may be commonly used but is not always enough. Thus, other superficial landmarks can make sure the structure palpated is truly the sacral hiatus and not other structure such as a lateral sacral foramen.…”

“…Most of all, the sacral hiatus may be identified by palpating the coccyx and moving in a cephalad direction until a depression in the skin is felt, but this method is sometimes difficult in children with obscure anatomical structures and obesity. 1,3 As another alternative, we devised a regression equation to calculate the distance between the midpoint of the PSISs and the actual sacral hiatus based on patient age, weight, and the distance between the PSISs and validated this equation by calculating the RMSE and performing cross-validation. The last alternative is the use of ultrasound.…”

“…1,2 The success of a caudal block is dependent on the proper insertion of a needle into the caudal epidural space with knowledge of the exact location of the sacral hiatus. 1 However, anatomical variations and obesity can make it difficult to identify the sacral hiatus.…”

“…1 However, anatomical variations and obesity can make it difficult to identify the sacral hiatus. 1,3 Textbooks and reviews of pediatric anesthesia have described identifying an equiangular triangle formed by the posterior superior iliac spines (PSISs) and sacral hiatus as an alternative or preferred approach to identifying the sacral hiatus. 4Y7 Many physicians are familiar with this equiangular triangle method, and in adults, some anatomical studies based on the morphometric analysis of desiccated sacral bones were conducted to validate whether this equiangular triangle is a reliable external landmark for conforming the sacral hiatus.…”

Spinal Anaesthetic Management in Paediatric Surgery

“…Shin et al confirmed that the end of the dural sac was at a median level of the upper S2 in children aged less than 36 months of age [14].…”