Olympus Gfum 20 Endoanal Ultrasound Analysis

Background
It was the famous Greek anatomist, surgeon and philosopher Galen (as documented by Holschneider and Wexner [1]) who first described the macroscopic anatomy of the anal sphincter complex (ASC). It took almost one and a half millennia for the first illustrations of the ASC to appear: by Versalius in 1543 [1]. Anatomist and surgeons have been undecided on the structure of the external anal sphincter (EAS) for centuries. In 1934, Milligan and Morgan described the EAS as being composed of 3 parts: from cranial to caudal, deep, intermediate and superficial parts [2]. With the development of Magnetic Resonance Imaging (MRI), all controversies ended when Hussain et al [3] described the Puborectalis muscle as the structure forming the deep

This probe has a 10 MHz ultrasound transducer that mechanically rotates inside a plastic cylinder, providing a 3600 view. The higher frequency (10 MHz vs 7 MHz) and having the sensor inside the plastic cylinder (vs water-filled balloon) has been identified to provide a better image quality [5].
All patients were positioned in the left lateral position and underwent the assessment without sedation. The probe was inserted in to the rectum after lubricating it. The anal canal and surrounding soft tissue were assessed for the morphology of the IAS, EAS and Puborectalis muscle. Endoanal Ultrasound (EAUS) describes the ASC as being divided in to 3 levels: upper, middle and lower [17]. Therefore, we measured the thicknesses of IAS at mid sphincter level at 3, 6, 9 and 12 o’ clock positions and the thicknesses of EAS at middle and lower sphincter levels at the same positions. The thickness of Puborectalis muscle at 6, 9 and 12 o’ clock positions was also measured (upper sphincter

However, for an abnormality or a defect to be identified, it must either be compared with a pre-morbid endo sonographic image of the same patient or against a normal set of values. It is the latter that is commonly done. Childbirth has been consistently identified as a risk factor for ASC injuries [23], with a higher risk in primi gravida [24]. Up to 67% - 92% [25] of mothers may have occult injuries detected on EAUS. Since all the participants of our study were Sri Lankan primi gravida, there may be concerns when directly extrapolating these values to Caucasians, males or non-pregnant females. However, previous publications on 3DEAUS have included only non-pregnant females [26], nulliparous females [11, 20] or post-partum females [12]. Therefore, we feel that our data fills a niche in the assessment of primi gravida and would be useful for clinical and research centres worldwide.
The EAS was consistently found to be thicker posteriorly and this may be due to the fact that only the internal part of the EAS encloses the entire circumference of the anal canal. The majority of EAS fibers merge with the transverse perinei muscles [20, 27]. In keeping with the existing knowledge [12, 13], we too observed that the length of the sphincter was also more laterally than elsewhere, possibly because of the fixation of the lateral part of the cranial end of the anal sphincters to the pelvic