Morphology of the Sacral Hiatus in an African Population – Implications for Caudal Epidural Injections

Abstract

Background The sacral hiatus exhibits variations in morphology which differ among populations. These variations may influence the success of caudal epidural injections for anaesthesia. This study describes the morphological and morphometric characteristics of the sacral hiatus in an adult Kenyan population. Study design A descriptive cross-sectional study. Materials and methods Eighty eight dry human sacra obtained from the Department of Osteology, National Museums of Kenya, Nairobi were used. The shape of the sacral hiatus was described as inverted-V, dumb-bell, inverted-U or irregular. The distance of the hiatal apex from the lower limit of S2 vertebra, the inter-cornual distance and the apical antero-posterior diameter were measured and tabulated. Results The inverted-V was the most common (32.1%) shape. The apex of the sacral hiatus was at the level of 4th sacral vertebra in 62% of cases. Mean distance of the hiatal apex from the S2 level was 43.1 + 12.9mm whereas antero-posterior diameter of the sacral hiatus at the apex was 6.4 + 3.1 mm. The sacral hiatus was absent in 1.2% of cases. Conclusion The level of the sacral hiatus in the African population implies minimal risk of dural puncture during caudal epidural injections.