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Abstract

The study was conducted on one hundred and seventeen human sacra to categorize the sacral hiatus of West Bengal population to improve the accuracy of caudal epidural block for anesthesia and analgesia. Various contours of hiatus were observed in this study which included inverted U (70.09%), inverted V (14.53%), irregular (12.82%), bifid (1.71%) and dumbbell (0.85%).The most frequently observed positions of apex and base of the hiatus were fourth and fifth sacral vertebrae respectively (74.36% and 95.73%). The average length, width and depth of hiatus were 20.21 mm, 12.10 mm and 6.02 mm with standard deviation of 7.7 3mm, 3.13 mm and 2.43 mm respectively. All the measurements were taken by Vernier calipers. Only in 27.35% cases the points on the lateral sacral crests at the level of first sacral foramina formed an equilateral triangle with the apex of the hiatus and thus could be used as an important landmark to locate sacral hiatus.

Key words

Sacrum, sacral hiatus, caudal epidural block, sacral cornua

Introduction

Caudal epidural block (CEB) is used for analgesia and anaesthesia in various clinical procedures where the medication is injected into the epidural space through the sacral hiatus (Chen et al., 2004). This approach to epidural space produces reliable and effective block of sacral nerves.

The opening present at the caudal end of sacral canal is known as sacral hiatus, which is formed due to failure of fusion of laminae of fifth (occasionally fourth) sacral vertebra. The sacral canal contains sacral and spinal nerve roots, the cauda equina, filum terminale externum, fibrous and fatty tissue, epidural venous plexus and spinal meninges (Standring et al., 2008).

In practice, the sacral hiatus is identified by palpation of the sacral cornua keeping the patient in the lateral position or lying prone over a pelvic pillow. These are felt at the upper end of the natal cleft 0.5 cm above the tip of the coccyx. Alternatively, the sacral hiatus may be identified by constructing an equilateral triangle based on a line joining the posterior superior iliac spines (Standring et al., 2008). Posterior superior iliac spines impose over the lateral sacral crest at the level of first sacral foramina ( Senoglu et al., 2005).

There are considerable variations in the size and shape...

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