Use of White Blood Cell Count and Negative Appendectomy Rate

Abstract

WHAT'S KNOWN ON THIS SUBJECT: Currently, the false-positive rate of appendicitis in children is #5%. Abdominal imaging and blood tests (particularly leukocytosis) help minimize the negative appendectomy rate, but appendicitis is not always associated with an elevated white blood cell count. WHAT THIS STUDY ADDS:Reducing the threshold of leukocytosis as a criterion for appendicitis to 8000 to 9000 white blood cells per mL improves specificity (negative appendectomy: ,1%) while only marginally decreasing sensitivity. abstract BACKGROUND: Despite increased utilization of laboratory, radiologic imaging, and scoring systems, negative appendectomy (NA) rates in children remain above 3% nationwide. We reviewed the clinical data of patients undergoing appendectomy to further reduce our NA rate. METHODS:A retrospective review was conducted of all appendectomies performed for suspected appendicitis at a tertiary children' s hospital during a 42-month period. Preoperative clinical, laboratory, and radiographic data were collected. Variables absent or normal in more than half of NAs were further analyzed. Receiver operating characteristic curves were constructed for continuous variables by using appropriate cutoff points to determine sensitivity and falsepositive rates. The results were validated by analyzing the 12 months immediately after the establishment of these rules. RESULTS:Of 847 appendectomies performed, 22 (2.6%) had a pathologically normal appendix. The only variables found to be normal in more than half of NAs were white blood cell (WBC) count (89%) and neutrophil count (79%). A receiver operating characteristic curve indicates that using WBC cutoffs of 9000 and 8000 per mL yielded sensitivities of 92% and 95%, respectively, and reduction in NA rates by 77% and 36%, respectively. Results observed in the subsequent 12 months confirmed these expected sensitivities and specificities.CONCLUSIONS: Absence of an elevated WBC count is a risk factor for NA. Withholding appendectomy for WBC counts ,9000 and 8000 per mL reduces the NA rate to 0.6% and 1.2%, respectively. Missed true appendicitis in patients with normal WBC counts can be mitigated by a trial of observation in those presenting with early symptom onset.

Total Leukocyte and Neutrophil count as preventive tools in reducing negative appendectomies

“…The area under the Curve (AUC) calculated by Bates M. F. et al was 0.86 and 0.87, respectively. [6] For this study, the AUC for TLC and NC was 0.96 and 0.987, respectively.…”

“…The sensitivity and specificity for NC was also analyzed. In the literature, the sensitivity and specificity for NC has been reported as; Anwar M. et al 82% and 68.75%, [18] Bates M. F. et al, 91% and 95%, [6] respectively. Their sample sizes were 100 and 847, respectively.…”

“…[6] Base line investigations like total leukocyte and neutrophil count are routinely carried out in every center due to the ease of availability and interpretation. [7] These are of special gust 2012 to May 2014.…”

“…All investigations were obtained at the Pathology Department of Khyber Teaching Hospital, Peshawar. Elevated TLC was taken as count >11.5×10 9 /Litre [6] and elevated Neutrophil count was taken as >75%11. Two ROC-curves were obtained for TLC and NC after applying Logistic Regression to achieve greater probability and accurate distribution.…”

An easy-to-follow algorithm to improve pre-operative diagnosis for appendicitis in children

“…Laboratory tests and other additional investigations help improve diagnostic accuracy. For instance, it has been shown that the combination of white blood count (WBC) and C-reactive protein (CRP) is highly sensitive for detection of inflammation and can be used to eliminate the diagnosis of appendicitis when both are normal [1][2][3]. Likewise, the sensitivity of imaging, essentially abdominal sonography, contributes to confirmatory diagnosis of appendicitis, enhances localization of the appendix and the degree of severity of appendicitis [4][5][6][7].…”