THE ROLE OF COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF ACUTE APPENDICITIS.

Stroman DL, et al. Am J Surg 1999 Dec;178(6):485-9

BACKGROUND: Routine contrast-enhanced computed tomography (CECT) has been described as an accurate diagnostic imaging modality in patients with acute appendicitis. However, most patients with acute appendicitis can be diagnosed by clinical findings and physical exam alone. The role of CECT in patients suspected of having appendicitis but with equivocal clinical exams remains ill defined.

METHODS: One hundred and seven consecutive patients who were thought to have appendicitis but with equivocal clinical findings and/or physical exams were imaged by CECT over a 12-month period. Oral and intravenous contrast-enhanced, spiral abdominal and pelvic images were obtained using 7-mm cuts. CECT images were interpreted by a board-certified radiologist. Main outcome measures included CECT sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy in the diagnosis of acute appendicitis, comparing CECT with ultrasound, and determining the impact of CECT on the clinical management of this patient population.

RESULTS: A group of 107 patients consisting of 44 males (41%) and 63 females (59%) with a median age of 33 years (range 13 to 89 years) were imaged with CECT to evaluate suspected appendicitis. Of the 107 CECTs performed, 11 false-positive and 3 false-negative readings were identified, resulting in a sensitivity of 92%, specificity of 85%, PPV of 75%, NPV of 95%, and an overall accuracy of 90%. Forty-three patients were imaged with ultrasound and CECT, and CECT had significantly better sensitivity and accuracy (30% versus 92% and 69% versus 88%, P<0.01). With regard to clinical management, 100% (36/36) of patients with appendicitis, and 4.2% (3/71) of patients without appendicitis underwent appendectomy. Therefore, the overall negative appendectomy rate was 7.6% (3/39).

CONCLUSIONS: CECT is a useful diagnostic imaging modality for patients suspected of having acute appendicitis but with equivocal clinical findings and/or physical exams. CECT is more sensitive and accurate than ultrasound and is particularly useful in excluding the diagnosis of appendicitis in those without disease.

UNENHANCED HELICAL CT FOR SUSPECTED ACUTE APPENDICITIS.

Lane MJ, et al. AJR Am J Roentgenol 1997 Feb;168(2):405-9.

OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of unenhanced helical CT scans in patients with a suspected acute appendicitis.

SUBJECTS AND METHODS: Over a 20-month period, 109 adult patients with suspected acute appendicitis were referred by the emergency department for an unenhanced helical CT scan. Each scan was obtained in a single breath-hold from the T12 vertebral body to the public symphysis using a 5-mm collimation and a pitch of 1.6. No patients were given oral or IV contrast media. The primary CT criteria for diagnosing acute appendicitis was the identification of an appendix with a transverse diameter larger than 6 mm with associated periappendiceal inflammatory changes. The presence of an appendicolith was considered a secondary finding as was isolated periappendiceal inflammation; however, appendicitis was not diagnosed in such patients unless an enlarged appendix was definitely identified. Final diagnoses were established by surgical or clinical follow-up and were compared with the original CT reports.

RESULTS: We found 66 true-negatives, 37 true-positives, four false-negatives, and two false-positives that yielded a sensitivity of 90%, a specificity of 97%, a positive predictive value of 95%, a negative predictive value of 95%, and an accuracy of 94%. An alternative diagnosis was established by an unenhanced helical CT scan in 24 patients (22%), which included cecal diverticulitis (seven patients), urinary tract disease (five patients), adnexal pathology (four patients), sigmoid diverticulitis (two patients), small bowel disease (three patients), right lower quadrant tumor (two patients), and an infected dialysis catheter (one patient).

CONCLUSION: Unenhanced thin-section helical CT is an accurate, effective technique for diagnosing acute appendicitis.

UNENHANCED SPIRAL CT FOR EVALUATING ACUTE APPENDICITIS IN DAILY ROUTINE. A PROSPECTIVE STUDY.

Pickuth D, Spielmann RP. Hepatogastroenterology 2001 Jan-Feb;48(37):140-2.

BACKGROUND/AIMS: The purpose of this study was to define in a routine setting the role of spiral computed tomography in patients with suspected acute appendicitis and to determine the effect of computed tomography on the treatment of such patients.

METHODOLOGY: Appendiceal computed tomography was performed in 120 consecutive patients with acute appendicitis in the differential diagnosis, whose clinical findings were insufficient to perform surgery or to discharge from the hospital. Each scan was obtained in a single breath hold from the lower abdomen to the upper pelvis using a 5-mm collimation and a pitch of 1.6. Computed tomography results were correlated with surgical and pathologic findings at appendectomy or clinical follow-up.

RESULTS: Eighty-eight of the 93 patients with acute appendicitis were correctly diagnosed by computed tomography, 24 of the 27 patients without acute appendicitis were correctly diagnosed by computed tomography (95% sensitivity, 89% specificity). Computed tomography signs of acute appendicitis included fat stranding (100%), enlarged appendix (> 6 mm) (97%), adenopathy (63%), appendicoliths (43%), abscess (10%), and phlegmon (5%).

CONCLUSIONS: The use of spiral computed tomography in patients with equivocal clinical presentation suspected of having acute appendicitis led to a significant improvement in the preoperative diagnosis and a lower negative appendectomy rate. Appendiceal computed tomography is an accurate technique even if performed in the daily routine of scanning.

COMMENTS: An unenhanced CT is rapid, has no contrast load, and allows visualization of urolithiasis in the work-up of equivocal patients with RLQ abdominal pain. However, a negative scan does not rule out an acute appendicitis. Those patients with a high clinical suspicion should get a surgical consultation or a re-scan with contrast.