The position and morphology of the vermiform appendix in Sri Lankans: a study on autopsies

The vermiform appendix is a vestigial structure showing extreme variability in its position. Varying symptoms of acute appendicitis reflect this variability making the clinical presentation of appendicitis highly inconsistent. Objective: To observe the anatomical variations of the position of the tip of the appendix and its base, length, details of meso-appendix and appendicular artery in adult medico-legal autopsies. Methods: A sample of medico legal autopsies carried out on those over 18 years by forensic pathologists at the Teaching Hospital Peradeniya was included in this study. Results: Of the 60 autopsies, 39 were male, with an age range of 19-88 years. Fifty eight appendixes were healthy, 1 appendicular mass and 1 absent appendix. Positions of the appendices were: 29 (50%) post-ileal, 20 (34.48%) retro-caecal, 7 (12.07%) pelvic and 2 (3.45%) para-caecal. The base was at the postero-medial wall in 36 (62.07%), lower pole in 18 (31.03%) and postero-lateral wall of the ceacum in 4 (6.0%) subjects. The length was 3cm 14 cm (mean 8.2 cm). The distance between ileo-caecal valve and base of the appendix was 1 cm 6 cm (mean 2.8 cm). The distance between the edge of the meso-appendix and the tip was 0 cm 7 cm (mean 1.23 cm). In 51.7 % of cases meso-appendix continued to the tip. The appendicular artery continued to the tip in 37 (63.8%) cases. Conclusions: Post ileal position is the commonest position of the appendix, with the base situated commonly on the postero-medial wall of the caecum. In the majority of cases mesoappendix and the appendicular artery continued to the tip. INTRODUCTION The Vermiform appendix is a vestigial structure in humans and is represented by a blind ended muscular tube, situated at the confluence of the three Taenia coli of the caecum. The appendicular base is described to have a relatively constant position in the postero-medial wall of the caecum (1), although it can sometimes be found on the postero-lateral wall and the lower pole of the caecum (1). The appendix is described to be of variable length but usually ranges from 7.5–10 cm in adults (1). The appendix is known to show extreme variability in its position and morphology. The classical positions described in the text books include retrocaecal, pelvic, pre-ileal, post-ileal, para-caecal, sub-caecal, and promonteric (2, 3). Even though it’s a vestigial structure with no proven function, it still qualifies attention due to the fact that it gets inflamed rather commonly, resulting in acute appendicitis, one of the most common cause for an acute abdomen in surgical casualties. Though a classical EKANAYAKE, P. M. N. S., AMARATUNGA, H. A., VADISINGHE, A. N., SENASINGHE, P., ADIKARI, S. B., The position and morphology of the vermiform appendix in Sri Lankans: A study on autopsies. Sri Lanka Anatomy Journal (SLAJ), 1(2): 31-34, 2017. 32 sequence of symptoms is described for acute appendicitis may vary making the clinical presentation of appendicitis highly inconsistent (4,5). The reason for this inconsistency could be due to the variability of its relationship with the surrounding structures. Notwithstanding the advances in modern radiographic imaging and laboratory investigations, the diagnosis of appendicitis remains essentially clinical, requiring adequate knowledge of the anatomical variations (6,7). Furthermore appendicitis may result in surgical removal of the appendix which requires a clear knowledge about the anatomy and relationships to other structures (8). Even though many studies have reported different positions of the appendix, racial differences may exist. The appendicular position in the Sri Lankan population has not been documented to date. Therefore it was the aim of our study to observe the anatomical variations, position of the tip of the appendix & its base, length, extent of the meso-appendix and the distribution of the appendicular artery, during medico-legal autopsies. METHODS A random sample of autopsies done by Forensic Pathologists from November 2011November 2012 at the Teaching Hospital Peradeniya was included in the study. Putrefied bodies, bodies with abdominal pathologies and abdominal trauma, surgical interventions or procedures necessitated to interfere with the position of the appendix, deformities which may affect the anatomy of the appendix (lower spinal abnormalities), microscopically abnormal appendices and any condition which could have affected length were excluded. Subjects whose age was below 18 years were excluded from the study. Ethical clearance was obtained from the ethical review committee of the Faculty of Medicine, University of Peradeniya. The anatomical details of the appendix were observed immediately after opening the abdominal cavity; before any manipulation the position of the tip of the appendix was noted. When the appendix was not visible the ceacum was mobilized and shifted carefully to observe the appendix. Next, the ilioceacal valve and the base of the appendix were identified. The exact position of the base on the wall of the caecum was noted. Then the length between the ileoceacal valve and the base of the appendix was measured using a calibrated metal Vernier caliper. The appendix was carefully unfolded and held straight. The length from the base to the tip was measured using the Vernier caliper. The mesoappendix was then studied carefully and the edge of the structure was located. Then the length between the edge of the mesoappendix and the tip of the appendix was measured with the Vernier caliper. All details were recorded in two diagrams specially designed for the purpose (figure 1 and 2). Figure 1: positions of the tip of the appendix 50 %