The Assessment of Laboratory Tests in the Diagnosis of Acute Appendicitis

Abstract

A comparison of laboratory tests was undertaken in 106 patients admitted to the emergency room with the tentative diagnosis of acute appendicitis and who subsequently underwent appendectomy. The tests examined included the total white blood cell count, manual differential count, cytochemical differential count, and C-reactive protein. The sensitivity, specificity, efficiency, and predictive value of these tests in the diagnosis of acute appendicitis were calculated. The cytochemically determined neutrophil count, when greater than the upper limit of the reference interval of either 75% or 7.88 X 10(9)/L, and the total white blood count greater than the upper limit of the reference interval of 10.5 X 10(9)/L were the single best tests for the diagnosis of acute appendicitis with the highest sensitivities of all tests examined (81-84%). The manual differential count and C-reactive protein showed significantly lower sensitivities. Test combinations also were examined. The combinations consisted of two or more tests joined by an "or" rule, i.e., if any one of the individually linked tests of the combination is above the reference interval, the combination is considered as indicating acute appendicitis. When either of the following test combinations were utilized--(1) total white count greater than 10.5 X 10(9)/L or cytochemical neutrophils greater than either 75% or 7.88 X 10(9)/L or CRP greater than 1.2 mg/dL; (2) total white count greater than 10.5 X 10(9)/L or manual bands greater than either 11% or 1.15 X 10(9)/L or CRP greater than 1.2 mg/dL--the sensitivity of the combination in the diagnosis of acute appendicitis approached 100% with a specificity in the range of 50%. We suggest that these test combinations may be useful in deciding which patients need further observation and reexamination prior to surgery. We also suggest the need for further studies to assess the usefulness of these tests in other types of acute inflammation and infection.

Laboratory Tests in Patients With Acute Appendicitis

“…Several reports suggest that an elevated leucocyte count is usually the earliest laboratory test to indicate appendiceal inflammation, and most of the patients with acute appendicitis present with leukocytosis. [6][7][8][9][11][12][13]15 The neutrophil percentage has also been thought to be of value, as a relative neutrophilia is often associated with bacterial infection. 9 In this study, the sensitivity of leucocyte count in diagnosing acute appendicitis was 85.8%, which is in accordance with other studies that reported a sensitivity of 82-96%.…”

“…Patients with acute appendicitis often present with a raised leucocyte count, but owing to a considerable overlap with other inflammatory processes mimicking acute appendicitis, the diagnostic value of the leucocyte count remains controversial. [3][4][5][6][7][8][9] Additional laboratory tests that aid in the diagnosis of acute appendicitis include the C-reactive protein (CRP), which is synthesized by hepatocytes during acute-phase response to a variety of infectious or inflammatory processes. Many reports have investigated the value of CRP in improving the diagnosis of acute appendicitis, but with conflicting results.…”

“…Many reports have investigated the value of CRP in improving the diagnosis of acute appendicitis, but with conflicting results. [6][7][8][9][10][11][12][13] In this study, the preoperative leucocyte count, neutrophil percentage and CRP values of patients undergoing appendicectomy for suspected acute appendicitis were correlated with the histopathology of the excised appendix. We evaluated the clinical applicability of these laboratory tests in the diagnosis of acute appendicitis and attempted to determine whether a normal leucocyte count and CRP value could effectively exclude the possibility of acute appendicitis.…”

Probability Machines

“…The appendicitis data set is from a published study on the assessment of 8 laboratory tests to confirm the diagnosis of appendicitis (26). Following surgery, only 85 out of 106 patients were confirmed by biopsy to have had appendicitis.…”

A Review of the Predictive Role of Plasma D-Lactate Level in Acute Appendicitis: A Myth or Truth?

“…Marchand et al pointed out that the positive predictive value (PPV) and negative predictive value (NPV) of an elevated WBC in AA are 92 and 50 percent, respectively [16]. Traditionally, patients are expected to have WBC counts between 12,000 and 18,000 per mm 3 with AA and 15,000 to 25,000 with perforated appendicitis.…”