Anatomical study of sacral hiatus in South Indian population and its clinical significance in caudal epidural anaesthesia

Abstract

Background: Caudal anaesthesia is administered into the epidural space through Sacral Hiatus(SH). Hence reliability and success of caudal epidural anaestheia depends upon the anatomical knowledge of sacral hiatus. Aim: The aim is to study the morphological measurements and variations of structures around the sacral hiatus and to identify possible anatomical reasons for failure of caudal epidural anaesthesia (CEA). Materials and methods: Fifty three dry adult sacral bones of both sexes were measured using Vernier Caliper, scale and divider. The shape of sacral hiatus (SH) was observed and its length and breadth were measured. The measurements were focused on sacral hiatus and its relation with surrounding bony projections. Results: The shape of the sacral hiatus showed a maximum occurrence of inverted ‘V’ and ‘U’ shapes with 35.85% and 26.42% respectively. The level of apex of SH was maximum at 54 foramen level in 68.63% cases followed by S5 and S3 level. In 62.26%, the level of base was observed at 55 level .The average length of the sacral hiatus was 23.02(± 8.95mm), AP diameter was 5.49 (± 1.44mm) and base of SH was 14.6 (± 3.99mm). The distance from apex and base of SH to S2 foramen level was 31.07mm and 52.86mm respectively. Conclusion: The anatomical knowledge of SH is very much necessary to increase the reliability and success of CEA. Surrounding bony irregularity, different shapes of hiatus and defect in dorsal wall of sacral canal should be taken into consideration before undertaking CEA so as to avoid its failure.

Keywords

• caudal epidural block
• sacral composition
• supero-lateral sacral crest
• sacral hiatus apex