Tc-99m-HMPAO White Blood Cell Scan for Diagnosis of Acute Appendicitis in Patients With Equivocal Clinical Presentation

Abstract

ObjectiveThe authors' goal was to evaluate the accuracy of Technetium 99m-HMPAO-labeled leukocyte imaging for screening patients with atypically presenting appendicitis and to determine how availability of this test affected practice patterns of surgeons at the authors' medical center. Summary Background DataAppendicitis can be difficult to diagnose and in equivocal cases usually requires inpatient observation. The delay may increase morbidity and costs. A test that rules out acute appendicitis could be cost effective if it allowed early discharge from the emergency department. Previously, there have been no simple, rapid, accurate noninvasive methods for improving diagnostic accuracy in patients with equivocal presentations of appendicitis. MethodsPatients referred to rule out appendicitis were analyzed. Patients were imaged up to 3 hours after injection of 10-mCi 99"Tc-HMPAO-labeled autologous leukocytes (Tc-WBC), and when the scans became positive, imaging was terminated and the requesting physician notified of the results. Diagnostic accuracy was established by surgical and histopathologic findings or by absence of symptoms after 1 month clinical follow-up. The source of referral, hospital length of stay, disposition of patients, and ancillary tests (ultrasound, computed tomographic scan, and barium enema) were analyzed. ResultsOne hundred twenty-four patients were studied from November 1991 through December 1995. Fifty-eight percent of positive scans showed uptake within 1 hour of injection and 73% by 2 hours. The Tc-WBC scan correctly identified an inflammatory source of abdominal pain in 65 of 66 cases (sensitivity = 98%) and was correctly negative in 55 of 58 cases (specificity = 95%). The scan correctly diagnosed appendicitis in 50 of 51 cases (sensitivity = 98%) and correctly excluded appendicitis in 62 of 73 cases (specificity = 85%). Outpatient referrals increased from 38% to 87%. In those patients with negative 58

Use of plasma DNA to predict mortality and need for intensive care in patients with abdominal pain

“…Strategies to improve the early diagnostic accuracy and riskstratification of patients presenting with acute abdominal pain have included clinical scoring methods [5,6], blood and urinary markers [7,8], ultrasound and CT imaging [5,[9][10][11][12][13][14] and minimally-invasive surgery [15]. The complexity of presentation of acute abdominal pain has not produced a simple score that is clinically useful.…”

Computed Tomography and Ultrasonography Do Not Improve and May Delay the Diagnosis and Treatment of Acute Appendicitis

“…During the last decade, studies of white blood cell scan, ultrasonography (US), and computed tomographic (CT) scan have suggested that these diagnostic imaging modalities may improve the diagnostic accuracy for acute appendicitis. [8][9][10][11] On the other hand, there were also concerns about the appropriateness and accuracy of these modalities without a surgical evaluation. 10,11 At our institution, history and physical examination, followed by pathologic confirmation after appendectomy, typically diagnose acute appendicitis.…”

99mTc Anti-CD 15 Monoclonal Antibody (LeuTech) Imaging Improves Diagnostic Accuracy and Clinical Management in Patients With Equivocal Presentation of Appendicitis

“…[10][11][12][13] The primary disadvantages of radiolabeled WBC imaging include a lengthy preparation time of 2 hours and sometimes longer if an off site radiopharmacy is used, the requirement of ex vivo white blood cell radiolabeling, the potential for external blood contamination and misadministration, personnel exposure to blood borne infection such as hepatitis and HIV, and the relatively high cost and technical demand of the procedure. Because of these disadvantages, very few medical centers are capable of using radiolabeled WBC imaging for the diagnosis of appendicitis.…”

“…10,11 This test was found to have high sensitivity (98%) and negative predictive value (98%), though a positive scan was not highly specific for appendicitis. Nonetheless, surgeons who received a positive scan result generally had a heightened degree of suspicion and treated the patient accordingly.…”