Study of Various Shapes of Sacral Hiatus in North Indian Population

SUMMARY Variations around sacral hiatus directly affect the outcome of caudal epidural block. The study is done to know the extent and anatomical variations of sacral hiatus in North Indian Population. The present study was carried on 89 dry human sacra of unknown sex. Each sacrum was studied for composition, shape of hiatus, and level of the apex of hiatus, level of the base of hiatus, length of hiatus, Anterio-posterior diameter and Transverse diameter at base of hiatus. All the measurements were taken with the Vernier caliper. Composition of sacra were observed with most common being 5 segments (70.11 %), 4 segments (2.29 %), 6 segments (partial/complete sacralisation) (11.49 %), coccygeal ankylosis (16.09 %). Diverse shapes of sacral hiatus were noted with most common being Inverted V (29.21 %), Inverted U (22.47 %), Irregular (20.22 %), Elongated (16.85 %), Dumb-bell (6.74 %), Bifid and complete agenesis of dorsal wall (2.24 %). Apex was found to be commonly located at 4th sacral vertebra (55.05 %). Base of hiatus was commonly located at 5th sacral vertebra (81.6 %). The mean length of sacral hiatus was 23.299.27mm. Mean Anterio-posterior diameter of sacral hiatus was 4.97 1.37mm. Narrowing of sacral hiatus at apex with diameter less than 3mm was observed in 14.94 % cases. Mean transverse diameter of sacral hiatus was 15.902.38mm. Sacral hiatus forms the basis of caudal epidural block. Hence, it becomes imperative to study different populations to know their pattern of variations.