Morphometric Measurement of Sacral Hiatus in Dry Human Sacrum

Abstract

Introduction: Sacral hiatus is the chief location for caudal epidural anesthesia during surgery of perineal region and also for a pain free parturition. Thus, this study was conducted to examine, measure and record the morphometry of sacral hiatus and to analyze it for any anatomical variations with clinical implications.

Methods: The cross-sectional study was carried in the Department of Anatomy, Sikkim Manipal Institute of Medical Science, Gangtok, Sikkim. For the study seventy dry human sacral bone with entire sacral hiatus were measured. The shape of the sacral hiatus was observed. Level of the apex, base, length, width and anterior posterior diameter of sacral hiatus was measured with Digital Vernier Caliper. The study was approved by Institutional Ethical Committee (IEC No:SMIMS/IEC/2017-01). Data were analysed by one-way analysis of variance (ANOVA) and the difference was considered significant when P<0.05. SPSS 20 was used for data analysis.

Results: The study revealed inverted “U” shaped sacral hiatus as the common shape in 35(50%) followed by inverted “V” shaped sacra in 18 (25.71 %) followed by irregular shaped sacral hiatus in 8 (11.42 %) cases. A Dumbbell shaped sacral hiatus was observed in 4 (5.71%) cases with a bony protuberance protruding medially from both edges. Absence or complete agenesis of sacral hiatus, a rare phenomenon, was observed in 3 (4.28%) and bifid in 2(2.85%) specimens only.

Conclusion: The prevalence of inverted “U” shaped sacral hiatus and constriction of the sacral canal at apex of sacral hiatus was found high. This knowledge of variation in shape of sacral hiatus could be clinically important while providing caudal anesthesia and doing epidural block.