A Morphometric and Morphlogical Study of Sacral Hiatus and its Clinical Significance in Caudal Epidural Anesthesia

Background: Sacrum is a triangular wedge-shaped bone which is formed by fusion of five sacral vertebrae. It is present between the two in nominate bones forming postero ? superior wall of pelvic cavity. Anatomy of the sacral hiatus is having clinical importance during caudal epidural block. In adults it is sometimes difficult to determine the anatomical location of the sacral hiatus and the caudal epidural space. Caudal epidural block (CEB) is widely used to provide anesthesia for various clinical procedures; treatment of lumbar spinal disorders and for the management of chronic back pain. Objective: To determine the shapes of sacral hiatus, Antero-posterior diameter and transverse width of sacral hiatus at the apex, and Distance between the sacral crest. Material and Methods: The study was conducted on 100 dried sacrum of unknown sex in Rajasthan population from the collection of Department of anatomy of Mahatma Gandhi Medical College and Hospital Jaipur. Results: Various shapes of sacral hiatus were observed which included Inverted- V (26%), Inverted- U (39%), Dumbell (11%), Elongated (2%), Bifid (17%), Irregular (5%). The mean anteroposterior diameter of sacral canal at the apex of sacral hiatus was 5.81mm. The mean transverse width of sacral hiatus at apex was 10.29mm. The mean value of distance between the two supero lateral crests and the distance between the apex of sacral hiatus and the right and left supero lateral sacral crests were 63.02, 62.18 and 47.95 mm respectively. Conclusion:The sacral hiatus has anatomical variations and these variations may improve the reliability of caudal epidural anaesthesia. There are anatomical variations in the shape and level of the sacral hiatus which may lead to failure of caudal anaesthesia.