Morphometric Analysis of Sacral Hiatus and it’s Clinical Relevance

Abstract

Background: Sacral Hiatus (SH) is an arched shaped gap on the dorsal surface of Sacrum just below the fourth tubercle. It is extensively used by anesthesiologists and Surgeons for Caudal Epidural Block, for therapeutic and diagnostic purposes. The success rate of Caudal Epidural Block depends upon the accuracy of palpation of Sacal Hiatus. It is sometimes difficult to locate it in adults due to various morphological variations. Morphometric measurements of Sacral Hiatus are of prime significance in locating Sacral Hiatus. Therefore, this study is aimed at analysing the various morphometric parameters of Sacral Hiatus to help in reducing the failure rate in Caudal Epidural Block.
Aim: To evaluate the various morphometric parameters of Sacral Hiatus in dry adult human sacrum.
Materials and Methods: This study was conducted on 50 fully ossified dry adult human sacra of unknown sex obtained from Santosh Medical College and Hospital, Ghaziabad. Measurements were taken using a digital Vernier caliper (accuracy 0.01 cm) and a flexible measuring tape. The various morphometric parameters of Sacral Hiatus assessed were: the shape of Sacral Hiatus, location of Apex and Base of Sacral Hiatus, length of Sacral Hiatus, Anteroposterior diameter at apex and transverse diameter at cornua of Sacral Hiatus. Data were analyzed using mean ± standard deviation and range.
Results: The SH apex was most commonly at S4 (60%) and the base at S5 (78%). SH length was 1–2 cm in 82% (mean 1.75 ± 0.66 cm). Anteroposterior diameter at apex measured 0.3–0.6 cm in 68% (mean 0.6 ± 0.15 cm), and transverse diameter at cornua was 1–2 cm in 80% (mean 1.49 ± 0.39 cm). Inverted U shape predominated (48%).
Conclusion: Sacral Hiatus exhibits significant morphological variations which are clinically relevant for Caudal Epidural Block. Understanding these variations and considering them can improve the success rate and minimize the complications.