Unusual extension of sacral hiatus - A case report

The laminae of fifth and sometimes fourth sacral vertebrae fail to fuse posteriorly in the sagittal plane leading to formation of a deficiency in the posterior wall of the sacral canal commonly known as sacral hiatus. During osteology demonstration class of MBBS students of the Department of Anatomy, U.C.M.S and G.T.B Hospital, Delhi, we noticed a sacrum in which sacral hiatus was extending to a level just inferior to the spinous process of second sacral vertebra. Review of literature suggested that the extent of sacral hiatus could be variable. To our knowledge, extension of sacral hiatus just inferior to spinous process of second sacral vertebra has not been described in the past. Familiarity with such kind of variation may help in administration of caudal epidural anaesthesia.