During recent years different procedures have been used to assist in d
iagnosis of questionable cases of appendicitis. Among these methods, t
here are few scoring systems that have been shown to be effective. The
aim of this study was to create a scoring system and to test its accu
racy in the preoperative diagnosis of acute appendicitis. Clinical dat
a from 360 patients who had undergone appendicectomy were collected to
identify attributes that distinguished patients having a negative lap
arotomy from those with appendicitis. Seven independent criteria were
identified. Using Bayesian methodology a weight was given to each crit
erion and an overall score calculated. A cut-off point was identified
to separate patients for surgery and those for observation. The scorin
g system was applied prospectively to 166 consecutive patients; 134 ha
d appendicitis and 32 a normal appendix (19.3 per cent error diagnosis
). For the 166 patients the method suggested surgery in 113, 107 (94.7
per cent) of whom were found to have appendicitis. The system suggest
ed observation in hospital in 38 cases. For the whole group the scorin
g system showed a sensitivity of 80 per cent and specificity of 81 per
cent. Scoring systems from a local database could become the ideal co
mplementary method in the diagnosis of suspected acute appendicitis.