The value of contrast-enhanced helical CT scan with rectal contrast enema in the diagnosis of acute appendicitis

• Published in: Clinical imaging Vol. 29; no. 4; pp. 255 - 258
• Main Authors: Naffaa, Lena N., Ishak, Gisele E., Haddad, Maurice C.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.07.2005; Elsevier; Elsevier Limited
• Subjects: Acute Disease; Adolescent; Adult; Aged; Aged, 80 and over; Appendicitis; Appendicitis - diagnostic imaging; Biological and medical sciences; Child; Contrast Media; Digestive system; Enema; Female; Gastroenterology. Liver. Pancreas. Abdomen; Humans; Imaging; Investigative techniques, diagnostic techniques (general aspects); Iohexol - analogs & derivatives; Iothalamic Acid - analogs & derivatives; Male; Medical sciences; Middle Aged; Nuclear polyhedrosis virus; Other diseases. Semiology; Predictive Value of Tests; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Retrospective Studies; Sensitivity and Specificity; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Tomography, Spiral Computed; CT; Appendicitis; Imaging; Radiodiagnosis; Acute; Rectum; Digestive diseases; Medical imagery; Intestinal disease; Contrast enema; Helical computed tomography; Diagnosis
• ISSN: 0899-7071; 1873-4499
• DOI: 10.1016/j.clinimag.2004.11.022

Background: The aim of this retrospective study is to assess the accuracy of single slice helical CT scan with intravenous, and rectal contrast (CTRC) in the diagnosis of acute appendicitis (AA) in patients with suspected AA, with particular analysis of the diagnostic signs. Participants and methods: Abdomino–pelvic helical CTRC was performed on 75 consecutive patients with suspicion of AA. Radiologic diagnosis was compared with surgical/pathologic results and clinical follow-up. In addition, the CTRC examinations were retrospectively reviewed independently by two experienced radiologists using predefined diagnostic criteria. The sensitivity, specificity, and frequency of each diagnostic sign were calculated. The interobserver agreement and the statistical significance of the frequency for each diagnostic criterion were assessed using the Kappa and Fisher tests, respectively. Results: The accuracy of helical CTRC in the diagnosis of AA was 94.7%, sensitivity 100%, specificity 90%, PPV 89.7%, and the NPV 100%. Wall enhancement and nonopacification of the appendix recorded the highest sensitivity and specificity (97% and 100%, 94% and 95%, respectively). Appendiceal thickness greater than 6 mm was present in 100% of true-positive cases. However, 26.5% of true-negative cases had also an appendiceal diameter exceeding 6 mm, a value used as a cut-off for normal appendiceal diameter. The highest interobserver agreement was recorded for appendiceal wall enhancement and for nonopacification of the appendix ( K=0.97 and 0.88, respectively). Conclusions: CTRC is an accurate and relatively fast technique for investigation of patients with suspected AA. A negative CTRC can exclude completely the diagnosis of AA. Nonopacification of the appendix and appendiceal wall enhancement are highly sensitive, specific, and reproducible, signs representing major criteria for the diagnosis of AA.