Rapid CT Diagnosis of Acute Appendicitis with IV Contrast Material

1. Rapid CT Diagnosis of Acute Appendicitis with IV Contrast Material S Mun*, K Chen*, S Shah*, A Oto*, W Mileski**, L Swischuk*, R Ernst* Dept. of Radiology* and Surgery** The University of Texas Medical Branch

2. Background • Controversy exists regarding the optimal use of IV, oral and rectal contrast in CT evaluation of suspected acute appendicitis • Some studies advocate non-oral contrast CT Lane et al; Malone et al; Peck et al; Stacher et al; Yuksekkaya et al • UTMB ED CT protocol was designed to accommodate high volume of patients requiring CT evaluation. Only IV contrast enhanced CT is utilized to aid in the diagnosis of suspected appendicitis

3. Purpose • To determine retrospectively the sensitivity and specificity of IV contrast enhanced CT without oral contrast in confirming suspected acute appendicitis

4. Materials and Methods • Patients studies were retrieved over an 8 month period (after institution of ED CT protocol) by a computer-generated search for “appendicitis” in the radiology reports • Studies with oral contrast, and without IV contrast were excluded • Patients age 17 and older with CT scans performed with IV contrast only were included in the study population

5. Materials and Methods • Reports of all patients were reviewed retrospectively • Pathology reports and medical records were reviewed • Patients without a histopathologic diagnosis of appendicitis who had no documented clinical follow-up of 1 week were excluded • Patients with indeterminate reports excluded

6. Materials and Methods • Results of CT reports were compared with clinical/pathology reports • Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated

7. Results • 271 patients were initially retrieved from the radiology report database • 59 patients were excluded • Unenhanced or oral contrast studies (n=54) • Pediatric patients (n=5) • 212 patients were included • Lost to follow-up (n=35) (16.5%) • Indeterminate cases, rescanned (n=4) (2.2%) • N= 173 Final study population

8. Results • Appendicitis was confirmed in 56 patients (32.4%) • Alternative diagnoses n=34 (19.6%) • Enteritis/colitis (n=9) • Acute gynecologic disorder (n=9) • Diverticulitis (n=5) • Urinary tract infection (n=4) • Cholecystitis (n=4) • Malignant neoplastic disease (n=3) • Pain subsided without specific diagnosis (n=80) (46.2%)

9. Results

10. Results • Sensitivity 100% • Specificity 97% • Positive predictive value 95% • Negative predictive value 100% • Time savings are approximately 1 hour

11. Images Inflamed appendix

12. Diverticulitis Diverticulitis

13. Images Cholecystitis

14. Images Pyelonephritis

15. Limitations • Some patients were lost to follow up, so excluded from the study • Computer-generated search for the word “appendicitis” may not have retrieved all patients presenting with RLQ pain • Acute appendicitis may have resolved with non-surgical treatment

16. Conclusions • IV contrast-enhanced helical CT without oral contrast material is a highly sensitive and specific technique for confirmation of suspected acute appendicitis • E D waiting time and patient delay to diagnosis may be improved