the vermiform appendix is the most variable abdominal organ in terms of position , extent , peritoneal , and organ relations [ 14 ] . knowledge of the variations in the position of the vermiform appendix is important because , in appendicitis , its variable positions may produce variable symptoms and signs which mimic other diseases [ 57 ] . further , understanding of these variations is important during other intra - abdominal procedures [ 4 , 8 ] . the length of the vermiform appendix is important in influencing the differential diagnosis of acute abdomen . ethnic and geographical variations have been reported regarding the position of the appendix ( table 1 ) . this variable anatomy may pose a challenge during appendectomy because it may necessitate extension of a transverse incision or additional muscle splitting . both these may complicate the surgery , prolong the operating time , and can affect the cosmetic outcome . although appendectomy still remains one of the most commonly performed surgical procedures in kenya [ 1012 ] , there is still scarcity of data on variant anatomy of the vermiform appendix in kenyans . this study therefore aimed to investigate the topography of the appendix in a black kenyan population . forty - eight human cadavers ( 37 males ) obtained during routine dissection in the department of human anatomy , university of nairobi , were studied . ethical approval was obtained from the kenyatta national hospital / university of nairobi ethics and review committee before commencement of the study . subjects with any gross abnormalities of abdominal organs , fibrosis , kinking or adhesions , and history of abdominal surgery were excluded . following resection of the anterior abdominal wall , the position of the base of vermiform appendix was determined using the schema derived by   ( figure 1 ) . measurement of the length of appendix from its base was taken using a string and a ruler . the distance from anterior superior iliac spine ( asis ) and umbilicus ( the spinoumbilical line ) was measured . mcburney 's point was taken to be the proximal two - thirds of the spinoumbilical line . the relation of the base of the appendix with mcburney 's point was determined and classified as cephalad , caudad , or along the spinoumbilical line . data collected was coded and entered in microsoft office access and analyzed using spss for windows version 18.0 ( chicago , illinois ) . the most common position of the appendix overall was retrocecal ( figure 2(a ) ) , followed by the pelvic type ( figure 2(b ) ) . other variations seen include preileal ( figure 2(c ) ) , subileal ( figure 2(d ) ) , postileal ( figure 2(e ) ) , and subcecal type ( figure 2(f ) ) . the commonest types in males were retrocecal 10 ( 27% ) and pelvic 10 ( 27% ) , while in females it was subileal 4 ( 36.4% ) . the average length of the appendix was 76.5  23.6  mm , with a minimum of 35  mm and maximum of 145  mm . the longest appendix was paracecal type ( 110.0  mm ) , while the shortest was subhepatic ( 63.0  32.5  mm ) . the average distance between the anterior superior iliac spine and umbilicus ( spinoumbilical line ) was 158.3  17.9  mm , with a minimum of 130  mm and a maximum of 200  mm . the base of the appendix was located along the spinoumbilical line in 25 ( 52.1% ) cases . in the remaining half in 9 ( 18.8% ) cases it was below and medial to the line , and in 14 ( 29.2% ) cases it was above and lateral to this line . for appendices that were located along the spinoumbilical line , the average distance from the anterior superior iliac spine to the base of the appendix was 83.9  11.5  mm , and thus most appendices were on average located approximately at the midpoint of spinoumbilical line and not at the popular mc burney 's point . for appendices located below and above the spinoumbilical line , they were 88.0  13.0  mm and 100  17.3  mm far from the anterior superior iliac spine , respectively ( table 3 ) . the classic teaching in many surgical training centers is that the appendix lies deep at the junction between the lateral and middle thirds of the right spinoumbilical line , so - called mc . however , in the current study , 48% of appendicular bases were not along the spinoumbilical line . this finding is clinically significant . in africa where open appendectomies form the significant majority [ 11 , 18 , 19 ] , surgeons need to be aware of this variation for preoperative planning and better surgical outcomes . current results postulate that trainee surgeons should not be surprised if the appendix is not easily visualized when a transverse incision is made at the mcburney 's point . a remarkable finding of the present study was that , of the 48% appendices that were not along the spinoumbilical line , approximately 30% were cephalic to this line and furthest from anterior superior iliac spine ( asis ) . naraynsingh et al . , using a double contrast postevacuation barium enemas for evaluating the mc . our study found an average distance of 100  mm , which is twice the previous study . this finding is clinically important because if the appendix is cephalic , access to the cecum becomes considerably more difficult when a transverse incision is made at the mc . it means surgeons in the study population may not find it uncommon to extend their incisions cephalad and do additional muscle splitting to locate the appendicular base . our findings also concur with ramsden et al .   from uk who found 15% of appendices were more than 10  cm from asis . a study by d. hegde and s. d. hegde ( 2008 ) , using 100 patients in whom a radio - opaque marker was placed during appendectomy , found a more superomedial location of the appendix in 75% of cases . the study by naraynsingh et al . also found 67% prevalence of appendices that were cephalic to spinoumbilical line . however , other studies found a more caudal location of the appendix in their populations . ramsden et al . from uk , for instance , found a more caudal position of the appendix in 75% of cases . the location of the appendix is important when it comes to clinical presentation of a patient with appendicitis . the area of tenderness in appendicitis will depend upon the length , position of the appendix , part of the appendix with inflammation , direction of the appendix , presence of fibrosis , and kinking or adhesions [ 1 , 22 ] . in the current study , most appendices were retrocecal ( 27% ) followed by pelvic ( 25% ) . our results are concordant with a similar african study from ghana , which found retrocecal prevalence of 67% . however , another african study from zambia   found a predominant pelvic position ( 43.6% ) . these differences may be due to genetic and lifestyle factors like nutritional regimens . retrocaecal appendicitis lacks distinctive clinical pattern and has been theorized to follow a more insidious course than other anatomic variants [ 17 , 25 ] . there is often limited systemic upset and no progression to affect the general peritoneal cavity . in retrocaecal appendicitis it is difficult to elicit tenderness on palpation in the right iliac region and even deep pressure may fail to elicit tenderness because the caecum , distended with gas , prevents the pressure exerted by the palpating hand from reaching the inflamed appendix , so it has been termed  silent appendicitis  . retrocecal appendix has also been postulated to have high chances of gangrenous complication because their blood supply is more prone to kinking and more liable to inflammation when fixed retrocecally . two studies looked at the retrocecal position of the appendix and its influence on clinical presentation . the study by herscu et al . , which looked at retrocecal anatomy and perforation rates at presentation , also found no significant association between retrocecal position and perforation rates . comparing these two studies with previous ones , further research is needed to definitively quantify the clinical relevance of retrocecal appendix . subhepatic location of the appendix is generally rare , with most cases being documented in case reports . a notable observation in the present study was the relatively high frequency of subhepatic appendix ( 4.2% ) , only comparable to 4% reported among pakistani 's . this position is thought to be caused by defective migration of the caecum during development or due to adhesions [ 7 , 29 , 30 ] . knowledge of this position is important because subhepatic appendicitis can cause a diagnostic dilemma as it may mimic hepatobiliary or renal disease [ 7 , 29 , 30 ] . mean length of the appendix in our study was 7.65  cm , within the range reported in the literature [ 4 , 23 , 24 ] . when inflamed , abnormally longer appendices may simulate inflammation of other structures such as enteritis , salpingitis , scrotal pains , and endometriosis [ 3133 ] . accordingly , appendicitis should always be considered as a differential diagnosis in acute abdomen even when the pattern of pain or tenderness is not at the right iliac fossa . the topography of vermiform appendix in kenyans shows variation from other populations . in a striking 30% of cases , the base of the appendix was cephalic to the mcburney 's point and furthest from anterior superior iliac spine . this means surgeons employing transverse incisions may need to do additional muscle splitting to locate the appendicular base . in this part of the world where open appendectomies are common , surgeons need to be aware of this variation for better operative outcomes .
background . topography of the appendix influences its mobility , degree of mobilization of the cecum , and need for additional muscle splitting during appendectomy . 
 although appendectomy is a common surgical procedure , there is a paucity of data on its topography in black africans .   methods . 
 the position and length of the appendix and relation of the appendicular base with spinoumbilical line were determined in 48 cadavers obtained from the department of human anatomy , university of nairobi , kenya . 
 results . 
 the commonest appendicular types in males were retrocecal 10 ( 27% ) while in females was subileal 4 ( 36.4% ) . 
 the average length of the appendix was 76.5  23.6  mm . 
 the base of the appendix was located along , below , and above the spinoumbilical line in 25 ( 52.1% ) , 9 ( 18.8% ) , and 14 ( 29.2% ) cases , respectively . conclusion . 
 the topography of appendix in kenyans shows variations from other populations . 
 knowledge of these variations is important during appendicectomy .