Rationale and Objectives
To assess the necessity of intravenous contrast medium for abdominopelvic computed tomography (CT) diagnosis of acute appendicitis (APP) among adult patients with right lower quadrant (RLQ) abdominal pain at emergency department (ED).
Materials and Methods
ED patients with clinical suspicion of APP from RLQ pain for a period of 8 months were enrolled retrospectively. Both pre- and postintravenous contrast-enhanced CT scans were performed for these patients. The visibility of vermiform appendix and specific CT findings of APP were recorded separately for noncontrast CT (NCT) and contrast-enhanced CT (CCT) images without knowledge of the patient’s identity and final diagnosis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CT diagnosis for APP were compared between the two groups. The ease of identifying appendix was also compared.
Results
Forty-two (42.0%) of the 100 patients (55 males, 45 females; age range, 16–90 years; mean age, 49.3 years) were APP. There was no significant difference for the visibility of appendix (94% vs. 91%; P = .589) and radiological characters between the CCT and NCT groups. There were significant differences between the two groups for sensitivity (100% vs. 90.5%; P = .036), specificity (94.8% vs. 100%; P = .038), PPV (93.3% vs. 100%; P = .021), NPV (100% vs. 93.5%; P = .021), but no significant difference for accuracy (97% vs. 96%; P = 1). The appendix was easier to detect on CCT than NCT images ( P = .013).
Conclusion
The diagnostic sensitivity of CCT was significantly better than that of NCT. Intravenous contrast administration could also make doctors easier in indentifying appendixes.
Acute appendicitis (APP) remains one of the leading causes of acute abdominal pain requiring surgical treatment in patients presenting to the emergency department (ED), occurring in 27.5% of surgical abdominal emergencies . Unfortunately, timely diagnosis remains clinically challenging, and the correct diagnosis is not made in at least 20% of patients with APP . Delays increase the risk of appendiceal perforation, postoperative complications and medical expenses .
As helical abdominopelvic computed tomography (CT) performed in patients with clinically suspected APP has shown high diagnostic accuracy (93% to 98%) and reduction of hospital resource utilization in many previous reports, the use of this imaging modality in diagnosing APP has increased steadily . Various methods to enhance the visibility of CT have been studied, and the protocol with intravenous contrast administration has proven to be an effective technique, which also reduced the negative appendectomy rate . However, with the increasing emphasis on the dose of radiation exposure and the risk of contrast-induced nephropathy or allergic reaction, noncontrast CT is particularly appealing in nowadays’ choice of diagnostic tests. The aim of this study was to assess the necessity of intravenous contrast medium for CT diagnosis of APP among adult patients at ED.
Materials and methods
Study Population
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Data Collation and CT Analysis
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Statistical Analysis
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Results
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Table 1
Etiologic Factors ( n = 100)
Etiology_n_ (%) Patients with acute appendicitis 42 (42.0%) Unruptured appendix 30 (71.4%) Ruptured appendix 12 (28.6%) Patients with non-acute appendicitis 58 (58.0%) Obstetric and gynecologic diseases 12 (20.7%) Pelvic inflammatory disease 7 (12.1%) Tuboovarian abscess 3 (5.2%) Ovarian cyst rupture 1 (1.7%) Ovarian tumor 1 (1.7%) Diverticulitis 9 (15.5%) Negative findings 9 (15.5%) Enterocolitis 8 (13.8%) Acute cholecystitis 4 (6.9%) Mesenteric adenitis 4 (6.9%) Ureteral stone 4 (6.9%) Intestinal obstruction 3 (5.2%) Others 5 (8.6%) Colon carcinoma 1 (1.7%) Hollow organ perforation 1 (1.7%) Pancreatitis 1 (1.7%) Pelvic spindle cell sarcoma 1 (1.7%) Retroperitoneal abscess 1 (1.7%)
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Table 2
Comparison of Radiological Data between NCT and CCT Images
NCT Patients with This Sign/No. of Patients CCT Patients with This Sign/No. of Patients Odd Ratio (OR) 95% Confidence Interval (CI)P Value Appendiceal diameter (>8 mm) 42/91 ∗ 47/94 † 0.08 0.03–0.24 .34 Appendiceal wall thickening 42/91 ∗ 46/94 † 0.20 0.10–0.39 .63 Presenting appendicolith 22/91 ∗ 19/94 † 0.04 0.01–0.13 .25 Periappendiceal inflammation 42/100 45/100 0.06 0.02–0.19 .51 Cecal wall thickening 45/100 45/100 0.23 0.13–0.42 1.00
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Table 3
Comparison of Statistic Data between NCT and CCT Images
NCT (%) CCT (%) Z_P_ Value Visibility 91.0 94.0 0.54 .589 Sensitivity 90.5 100.0 2.92 .036 Specificity 100.0 94.8 2.07 .038 PPV 100.0 93.3 2.31 .021 NPV 93.5 100.0 2.31 .021 Accuracy 96.0 97.0 0.00 1.000
CCT, contrast-enhanced computed tomography; NCT, noncontrast computed tomography; NPV, negative predictive value; PPV, positive predictive value.
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Discussion
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References
1. Karam A.R., Birjawi G.A., Sidani C.A., et. al.: Alternative diagnoses of acute appendicitis on helical CT with intravenous and rectal contrast. Clin Imaging 2007; 31: pp. 77-86.
2. Anderson B.A., Salem L., Flum D.R.: A systematic review of whether oral contrast is necessary for the computed tomography diagnosis of appendicitis in adults. Am J Surg 2005; 190: pp. 474-478.
3. Tamburrini S., Brunetti A., Brown M., et. al.: Acute appendicitis: diagnostic value of nonenhanced CT with selective use of contrast in routine clinical settings. Eur Radiol 2007; 17: pp. 2055-2061.
4. Zyluk A., Ostrowski P.: An analysis of factors influencing accuracy of the diagnosis of acute appendicitis. Pol Przegl Chir 2011; 83: pp. 135-143.
5. Pickhardt P.J., Lawrence E.M., Pooler B.D., et. al.: Diagnostic performance of multidetector computed tomography for suspected acute appendicitis. Ann Intern Med 2011; 154: pp. 789-796.
6. Kim K., Rhee J.E., Lee C.C., et. al.: Impact of helical computed tomography in clinically evident appendicitis. Emerg Med J 2008; 25: pp. 477-481.
7. Kim K., Lee C.C., Song K.J., et. al.: The impact of helical computed tomography on the negative appendectomy rate: a multi-center comparison. J Emerg Med 2008; 34: pp. 3-6.
8. Rao P.M., Rhea J.T., Novelline R.A., et. al.: Effect of computed tomography of the appendix on treatment of patients and use of hospital resources. N Engl J Med 1998; 338: pp. 141-146.
9. Lin K.H., Leung W.S., Wang C.P., et. al.: Cost analysis of management in acute appendicitis with CT scanning under a hospital global budgeting scheme. Emerg Med J 2008; 25: pp. 149-152.
10. Schuur J.D., Chu G., Sucov A.: Effect of oral contrast for abdominal computed tomography on emergency department length of stay. Emerg Radiol 2010; 17: pp. 267-273.
11. Hlibczuk V., Dattaro J.A., Jin Z., et. al.: Diagnostic accuracy of noncontrast computed tomography for appendicitis in adults: a systematic review. Ann Emerg Med 2010; 55: pp. 51-59.
12. Bendeck S.E., Nino-Murcia M., Berry G.J., et. al.: Imaging for suspected appendicitis: negative appendectomy and perforation rates. Radiology 2002; 225: pp. 131-136.
13. Torbati S.S., Guss D.A.: Impact of helical computed tomography on the outcomes of emergency department patients with suspected appendicitis. Acad Emerg Med 2003; 10: pp. 823-829.
14. Lu C.L., Liu C.C., Fuh J.L., et. al.: Irritable bowel syndrome and negative appendectomy: a prospective multivariable investigation. Gut 2007; 56: pp. 655-660.
15. Moteki T., Horikoshi H.: New CT criterion for acute appendicitis: maximum depth of intraluminal appendiceal fluid. AJR Am J Roentgenol 2007; 188: pp. 1313-1319.
16. Rao P.M., Mueller P.R.: Clinical and pathologic variants of appendiceal disease: CT features. AJR Am J Roentgenol 1998; 170: pp. 1335-1340.
17. Rao P.M., Rhea J.T., Novelline R.A.: Sensitivity and specificity of the individual CT signs of appendicitis: experience with 200 helical appendiceal CT examinations. J Comput Assist Tomogr 1997; 21: pp. 686-692.
18. Rao P.M., Rhea J.T., Novelline R.A., et. al.: Helical CT technique for the diagnosis of appendicitis: prospective evaluation of a focused appendix CT examination. Radiology 1997; 202: pp. 139-144.
19. Ives E.P., Sung S., McCue P., et. al.: Independent predictors of acute appendicitis on CT with pathologic correlation. Acad Radiol 2008; 15: pp. 996-1003.
20. Shin L.K., Jeffrey R.B.: Sonography and computed tomography of the mimics of appendicitis. Ultrasound Q 2010; 26: pp. 201-210.
21. Kruszka P.S., Kruszka S.J.: Evaluation of acute pelvic pain in women. Am Fam Phys 2010; 82: pp. 141-147.
22. Hill B.C., Johnson S.C., Owens E.K., et. al.: CT scan for suspected acute abdominal process: impact of combinations of IV, oral, and rectal contrast. World J Surg 2010; 34: pp. 699-703.
23. Hekimoglu K., Yildirim U.M., Karabulut E., et. al.: Comparison of combined oral and i.v. contrast-enhanced versus single i.v. contrast-enhanced MDCT for the detection of acute appendicitis. JBR-BTR 2011; 94: pp. 278-282.
24. Funaki B.: Nonenhanced CT for suspected appendicitis. Radiology 2000; 216: pp. 916-918.
25. Lane M.J., Katz D.S., Ross B.A., et. al.: Unenhanced helical CT for suspected acute appendicitis. AJR Am J Roentgenol 1997; 168: pp. 405-409.
26. Anderson S.W., Soto J.A., Lucey B.C., et. al.: Abdominal 64-MDCT for suspected appendicitis: the use of oral and IV contrast material versus IV contrast material only. AJR Am J Roentgenol 2009; 193: pp. 1282-1288.
27. Lee K.H., Kim Y.H., Hahn S., et. al.: Computed tomography diagnosis of acute appendicitis: advantages of reviewing thin-section datasets using sliding slab average intensity projection technique. Invest Radiol 2006; 41: pp. 579-585.
28. Cole M.A., Maldonado N.: Evidence-based management of suspected appendicitis in the emergency department. Emerg Med Pract 2011; 13: pp. 1-29.
29. Flum D.R., Koepsell T.: The clinical and economic correlates of misdiagnosed appendicitis: nationwide analysis. Arch Surg 2002; 137: pp. 799-804.