Morphometrical analysis of sacral hiatus and its clinical significance

Aim: To find some important landmarks to enhance the location of apex of sacral hiatus for successful caudal epidural block and also a detailed morphometric analysis of Sacral hiatus. Material and methods: Thirty dry sacral bones were used. Parameters pertaining to the sacral hiatus were determined and readings were taken. Measurements were made using Vernier caliper accurate to 0.1 mm. Results: The dorsal wall of the sacrum was deficient in two cases. The determined bony landmarks favoured the formation of an equilateral triangle. The apex of sacral hiatus was found to occur at 3rd in 46% and 4th in 46% level of sacrum, and the position was found to be varying between 2nd to 4th sacral levels. The mean antero-posterior diameter of sacral canal at the level of apex was found to be 5.9 (2.09) mm (range 4-10 mm), in 16 (57%) sacrum it was between 4-6 mm. In 10 (35%) sacra the shapes were found to be Inverted?U and as Inverted?V respectively. In 8 (28%) sacra the shape was found to be Irregular. Conclusion: The given bony landmarks in combination with other technique would improve the success rate of caudal epidural block. The variabilities provided in this study should be kept in mind before giving caudal epidural Block.