variations of sacral hiatus in dry human sacra: an anatomical study

BACKGROUND Sacrum is a large triangular bone formed by the fusion of 5 sacral vertebrae. It lies obliquely at the posterior part of pelvic cavity between the two hip bones. It encloses a canal called the sacral canal. The lower opening of the sacral canal is called the sacral hiatus. It transmits the 5 th pair of sacral nerves, coccygeal nerves & filum terminale externa. AIMS & OBJECTIVES The aim of the present study is to find out the variations of sacral hiatus in this part of Northeast India. MATERIALS & METHODS The study was carried out in 104 dry human sacra to know the anatomical variations of sacral hiatus. The measurements were carried out with the help of a Vernier calliper, scale & a divider. RESULT & OBSERVATIONS Various shapes of sacral hiatus were observed as follows: Inverted U shaped (53.8%), inverted V shaped (29.8 %), irregular shaped (9.6 %), dumb-bell shaped (5.7 %), bifid (0.9%). The length of the sacral hiatus was found to be between 20-30 mm in 46.1% cases. The apex of the sacral hiatus was at the level of S4 vertebra in 46.1% specimens. The anteroposterior diameter of the sacral canal at the apex of the sacral hiatus ranged from 2-12 mm. CONCLUSIONS Variations of sacral hiatus is very common. The knowledge of such variations will definitely help the anaesthesiologists to take proper step while administering caudal epidural anaesthesia to increase the success rate of caudal epidural block.