Morphometric study of sacral hiatus in adult human Egyptian sacra: Their significance in caudal epidural anesthesia

Abstract

Background:The reliability and success of caudal epidural anesthesia depends on anatomic variations of sacral hiatus (SH) as observed by various authors. SH is an important landmark during caudal epidural block (CEB).The purpose of the present study was to clarify the morphometric characteristics of the SH in human Egyptian dry sacra and pelvic radiographs and identification of nearest ony landmarks to permit correct and uncomplicated caudal epidural accesses.Methods:The present study was done on 46 human adult Egyptian dry sacra. The maximum height, midventral curved length, and maximum breadth of each sacrum were measured and sacral and curvature indices were calculated. According to sacral indices, sacra were divided into 2 groups (22 male and 24 female sacra). SH was evaluated in each sacrum according to its shape, level of its apex, and base according to sacral and coccygeal vertebrae, length, anteroposterior (AP) diameter at its apex, and transverse width at its base. Linear distances were measured between the apex of SH and second sacral foramina, right and left superolateral sacral crests. The distance between the 2 superolateral sacral crests also was measured.Results:The most common types of SH were the inverted U and inverted V (in male) and inverted V and dumbbell shaped (in female). Absent SH was observed in male group only. The most common location of SH apex was at the level of S4 in all groups of dry sacra and S3 in all groups of lumbosacral spine radiographs, whereas S5 was the common level of its base. The mean SH length, transverse width of its base, and AP diameter of its apex were 2.1±0.80, 1.7±0.26, and 0.48±0.19 cm. Female sacra showed narrower SH apex than male. The distance between the S2 foramen and the apex of the SH was 4.1±1.14, 3.67±1.21, and 4.48±1.01 cm in total, female and male sacra, respectively.Conclusion:Sacrum and SH showed morphometric variations in adult Egyptians. The equilateral triangle is an important guide to detect SH easily and increases the success rate of CEB. Insertion of a needle into the SH for caudal block is suggested to be done at its base to avoid the anatomic variations of its apex.

Assessment of Morphological and Morphometrical Variations of Sacral Hiatus in Dry Human Sacrum in Ethiopia

“…The shape of the SH is one of the most important landmarks. 15 , 16 Inverted-V (41%) and inverted-U (37.7%) were the most common types, somewhat similar to the results of the study by Ukoha et al 24 who reported inverted-V (33.1%) and inverted-U (24%). This was contradictory to the observations by Bhattacharya et al 25 who reported inverted-U (65%) and inverted-V (23%), and Doshi et al 26 who reported inverted-V (14%) and inverted-U (56%).…”

“…In addition to this, anatomic variations in size, shape and orientation of the sacral hiatus increase the problems in caudal anesthesia. 15 , 16 …”

Ultrasound as a Screening Tool for Performing Caudal Epidural Injections

“…It has been mentioned in another cadaveric study that dimensions of the triangle formed by the right and left posterosuperior iliac spines with the apex of the hiatus, the optimal angle of needle insertion and the depth of the caudal space are mainstays of anatomical landmarks ( 18 ). Morphometric characteristics of the sacral hiatus in 46 Egyptian dry sacra clarifies that a less than 3 mm anteroposterior diameter of hiatus in Egyptian females and an absent sacral hiatus in Egyptian males should be taken into consideration before caudal epidural block to avoid its failure ( 19 ).…”

“…Epidurogram showed that the injection was out of the sacral canal in these eight patients. It has been reported that sacral canal diameters of 2 mm or less ( 21 ), around 1.5 mm ( 12 ) or less than 3 mm ( 19 ) can result in the increased failure rate of caudal epidural injections and a sacral canal diameter of 2.9 mm is adequate for performing successful injection ( 12 ). These findings were in agreement with the results of our study that a sacral hiatus diameter of 1.5-1.9 mm results in failed caudal epidural injection.…”

Anatomical Differences in Sacral Hiatus During Caudal Epidural Injection with Ultrasonography Guidance and Its' Effect on Success Rate

“…[19] Başka bir çalışmada ise 46 Mısırlı kadavrada sakral hiatusunun anatomik yapısının incelemesinde kadınlarda ve erkeklerde 3 mm'den daha küçük olan sakral hiatusda kaudal bloğun başarısız olma ihtimali dikkate alınmalıdır sonucu çıkarılmış. [23] Bizim çalışmamızda ise USG kullanarak 255 hastanın 253'ünde sakral hiatus anatomisi görülebildi ve bu da USG'nin kemik yapılarda anatomiyi değerlendirmede değerli bir araç olduğunu gösterdi. Başarılı olmayan kaudal epidural enjeksiyonlu 6 hastanın 2'sinde sakral hiatus USG görüntüleri ile tanımlanamamıştır ve bu hastalara skopi altında da işlem başarısız olmuştur.…”