Incidence of normal white cell count and C-reactive protein in adults with acute appendicitis.
BACKGROUND
Normal C-reactive protein (CRP) and white cell count (WCC) are often used to exclude a diagnosis of acute appendicitis in the Emergency Department (ED). Retrospective review of 281 adult patients with acute appendicitis was performed to study the incidence of normal CRP and WCC on admission and examine any possible predisposing factors.


METHODS
Retrospective analysis of patient clinical records yielded CRP, WCC, operative diagnosis, time of symptom onset, imaging results and history and examination features. Case-control analysis was performed with patients with normal CRP and WCC considered the case group and those with raised CRP or WCC considered controls. Groups were compared using Mann-Whitney U-test and chi-squared analysis.


RESULTS
Of 281 consecutive patients with histologically proven appendicitis, 24 (8.54%) had normal CRP and WCC on presentation to ED. There were no significant differences in age, sex or time to blood collection between groups. Three patients had normal WCC and CRP and an Alvarado score of 4 or less on presentation. Three patients had persistently normal CRP and WCC on repeated testing. There was a trend towards earlier presentation in patients with normal CRP and WCC with 75.0% versus 58.4% presenting within 24 h of symptom onset (OR 2.14, P = 0.112).


CONCLUSIONS
Acute appendicitis remains diagnostically challenging and cannot be excluded on the basis of normal CRP and WCC. Serial clinical and biochemical assessment is warranted in patients with acute abdominal pain, particularly in those presenting early after symptom onset.
Department of General Surgery, Sandringham Hospital, Melbourne, Victoria, Australia.
Nalin H
NH
Dayawansa
Department of General Surgery, Sandringham Hospital, Melbourne, Victoria, Australia.
Julian D S
JDS
Segan
Department of General Surgery, Sandringham Hospital, Melbourne, Victoria, Australia.
Henry H I
HHI
Yao
Department of General Surgery, Sandringham Hospital, Melbourne, Victoria, Australia.
Hon I
HI
Chong
Department of General Surgery, Sandringham Hospital, Melbourne, Victoria, Australia.
Paul J
PJ
Sitzler
D000208:Acute Disease; D000328:Adult; D001062:Appendectomy / Q000379:methods; D001064:Appendicitis / Q000097:blood* / Q000175:diagnosis* / Q000601:surgery; D001315:Australia; D002097:C-Reactive Protein / Q000032:analysis*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D016001:Confidence Intervals; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007958:Leukocyte Count / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012016:Reference Values; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D062606:Tertiary Care Centers; D016896:Treatment Outcome; D055815:Young Adult
D002097:C-Reactive Protein
C-reactive protein; abdominal pain; appendectomy; appendicitis; white blood cell count