Inflammation of a retrocaecal appendix will produce pain when there is which of the following movements at the hip:
a. Obturator sign: If an inflamed appendix is in contact with the obturator internus, spasm of the muscle can be demonstrated by flexing and internally rotating the hip. This manouvre will cause pain in the hypogastrium.
b. The appendix has been described as lying in several ‘classic’ sites, but apart from the true retrocaecal appendix, the organ probably floats in a broad arc about its base
c. Only inflammation will fix it in a particular place. Its position will then determine the clinical presentation of the disease.
d. In about 30% of appendicectomies, the appendix lies over the brim of the pelvis (‘pelvic appendix’). This is adjacent to the bladder and rectum in males and to the uterus, Fallopian tubes and bladder in females.
e. In some cases, the appendix lies retroperitoneally behind the caecum and is often plastered to it by fibrous bands.
f. Thus, an inflamed retrocaecal appendix may irritate the right ureter and psoas muscle, and may even lie high enough to simulate gall-bladder pain.
g. Additional information: An inflamed retrocaecal appendix produces none of the usual localising symptoms or signs, but may irritate the psoas muscle causing involuntary right hip flexion and pain on extension.