Variation in the morphology and morphometry of the human sacral hiatus and its clinical relevance in caudal epidural anaesthesia

Background: The sacrum forms an essential component of the pelvic girdle and exhibits marked anatomical variability. Of particular clinical interest is the sacral hiatus, which serves as the access point for caudal epidural anaesthesia. Knowledge of its morphology and dimensions is also useful in forensic identification and medico?legal practice.Materials and Methods: The present cross?sectional study was performed on 200 dry adult human sacra obtained from the Departments of Anatomy at Zydus Medical College, Dahod, and B. J. Medical College, Ahmedabad. The sacral hiatus was evaluated for its shape, vertebral level of the apex and base, length, anteroposterior diameter at the apex, and intercornual distance at the base. Standard osteometric instruments were used for all measurements.Results: The sacral hiatus demonstrated considerable variation in shape and dimensions. The most frequently observed configuration was the inverted U shape, followed by inverted V and irregular types. The apex was most commonly located at the level of the fourth sacral vertebra, while the base was usually at the level of the fifth sacral vertebra. Most specimens showed a hiatus length between 11 and 30 mm, with an anteroposterior diameter at the apex commonly ranging from 4 to 6 mm.Conclusion: Appreciable anatomical variability exists in the sacral hiatus. Awareness of these variations is important for improving the success rate and safety of caudal epidural anaesthesia, particularly in the adult Indian population.