ABSTRACT
Introduction: The sacral hiatus is located on the posterior aspect of the lower end of the sacrum, where theextradural space ends . The clinically significant features of the posterior surface of the sacrum are the triangularor inverted ‘U’ shape sacral hiatus and the sacral cornua.The knowledge of Anatomical variations of Sacralhiatus is significant while administration of Caudal Epidural Anaesthesia and it may help to improve its successrate.Aim: The purpose of this study is to recognize anatomical variations and additional landmarks of sacral hiatusin cases where the sacral cornua could not be identified and to assess proportions that may magnify the locationof the apex of the sacral hiatus and thus to find a practical solution for Caudal epidural block (CEB).Materials and methods: The present study was conducted on unknown sixty one complete and undamaged adult,dry sacral bones . The material was of undetermined age and gender. Anatomical measurements was carried outon these bones using a vernier calliper to the accurate of 0.1mm.Results: Variations in the shapes and their percentages of Sacral hiatus were observed namely Elongated, InvertedU, Irregular, Inverted V, Dumbbell and Bifid along with their distances and Angles of use in detecting the Apexwere measured. The location of Apex of Sacral hiatus was found at varying levels from upper end of S2 to lowerpart of S5 vertebrae. Also we measured the angles between the margins of the triangle formed by the twosuperolateral sacral crests and the sacral hiatus. Our measurements reveal this to be an equilateral triangle.Conclusion: This knowledge of variations in Human sacral hiatus provides a safe caudal epidural block beforesurgery and complications can be avoided.We believe that the equilateral character of the sacral triangleformed connecting the two posterior superior iliac spines and the apex of the sacral hiatus will be practicaladvantage to the clinician in ascertaining the location of the sacral hiatus during CEB.
ABSTRACT
Background: The sacral hiatus is the site for caudal epidural anaesthesia during perineal surgery and also for a painless delivery. It is also used for three dimensional colour visualization of lumbosacral epidural space in orthopaedic practice for diagnosis and treatment. Sacrum is one of the bones which exhibit variations. Therefore the importance of the normal sacral hiatus and its variations is of great clinical significance. The reliability of caudal epidural anaesthesia is 70% - 80% in the literatures. The objective of the study was to examine, measure and record the morphometry of sacral hiatus under the following headings in order to study the anatomical variations which would be useful for caudal epidural anaesthesia and improve the reliability of the same. a) Shape of sacral hiatus, b) level of apex, c) level of base, d) length of the sacral hiatus, e) transverse width at the base, and f) anteroposterior depth at the apex. Methods: A total of 200 dry, complete, undamaged human sacra of unknown sex were used in this study. Measurements were taken using vernier calipers. In this study six parameters were taken. All the readings were tabulated and subjected to analysis. Results: Various shapes of sacral hiatus were observed which included Inverted-U (50%), Inverted-V (27.5%), Irregular (15.5%), Dumb bell (2%), and Bifid (2%). The mean anteroposterior depth of sacral canal at the level of apex of sacral hiatus was 4.25mm. The mean length of sacral hiatus was 19.63 mm and the mean transverse width of sacral hiatus at the level of base was 11.42 mm. There was complete spina bifida in 4 (2%) and absence of sacral hiatus in 2 (1%) cases. Conclusion: The sacral hiatus has anatomical variations. Understanding of these variations may improve the reliability of caudal epidural anaesthesia.