journal club discussing acute appendicitis.pptx

Radiological findings in acute appendicitis and diagnosis using different modalities. recent updates in diagnostic criteria

1. JOURNAL CLUB 17/05/2024

2. Update on acute appendicitis: Typical and untypical findings S. Borruel Nacenta , L. Ibánez Sanz, R. Sanz Lucas, M.A. Depetris , E. Martínez Chamorro

3. AIMS To define the diagnostic criteria for appendicitis in different imaging modalities (ultrasonography, computed tomography, and magnetic resonance imaging) To explain the diagnostic protocols, atypical presentations, and other conditions that can mimic appendicitis.

4. Introduction Acute appendicitis (AA) is the most common indication for emergency abdominal surgery throughout the world Annual incidence of 96.5 to 100 cases per 100,000 adults Recent clinical trials suggest that in 60% of patients, uncomplicated AA can be treated with antibiotics only Diagnostic imaging is central to identifying which patients can be treated without surgery

5. Diagnosis of acute appendicitis. Imaging techniques

6. Ultrasonography Excellent initial imaging technique Sensitivity (S) and specificity ( Sp ) of ultrasound is 86% and 81%, respectively

7. CT There is consensus on scanning the entire abdomen to include atypically located appendices and other causes of abdominal pain. Intravenous contrast improves sensitivity Only perform CT after an inconclusive ultrasound or in exceptional circumstances as the first line of diagnosis in obese patients, the very old or patients suspected of having complicated appendicitis and peritonism making ultrasound assessment difficult. CT of the entire abdomen in the portal phase except where contraindicated, without oral contrast, and low-dose scans in young patients

8. MRI ACR recommends it in children and pregnant women to avoid exposure to radiation It is indicated after an inconclusive ultrasound. Apnoea sequences with fat suppression on T1 and T2 (axial and coronal planes), diffusion in case of suspected complication.

9. The normal appendix is an aperistaltic tubular structure with a blind end. Its wall is less than 3 mm thick and its maximum transverse diameter is less than 6 mm

10. Diagnostic criteria Increased appendix diameter –can’t consider it in isolation. Faecal impaction or gas increase the diameter of the appendix. On ultrasound, the appendix is measured along its axial axis from serosa to serosa and is considered abnormal if it is greater than 7 mm. In CT and MRI, the cut-off should be higher as it is being measured without appendiceal compression, and considered abnormal when greater than 10 mm.

11. 2. Thickening and stratification of the wall – In all imaging techniques, the thickness of the appendix wall is considered to be increased when it measures more than 3 mm In ultrasound it has to be measured from the mucosal surface to the serosa, excluding the endoluminal content Assessment of the layers of the appendix is more useful than wall thickness Appendix has five layers with alternating echogenicity, three hyperechoic, which are (from the inside out) the mucosal surface, the submucosa and the serosa, and between them two hypoechoic layers, the muscularis mucosa and muscularis propria. First mucosa disappears, followed by thickening of submucosa Then there could be breaks in submucosa and eventually it disappears.

12. 3. Inflammation and vascularisation of the appendix wall Appears as an increase in Doppler flow in the wall of the appendix Absent in gangrenous appendicitis On CT there is enhancement of the wall of the appendix. This is best seen with dual-energy CT scanners On MRI, hyperintensity is seen on T2-weighted images with diffusion restriction 4. Non-compressible appendix Pain coinciding with the pressure of the transducer Presence of an appendix that cannot be compressed

13. 5. Inflammation of the periappendiceal fat Best diagnostic criterion for AA On ultrasound it is seen as an increase in the echogenicity of the periappendiceal fat On CT as an increase in attenuation, and on MRI as hyperintensity in T2-weighted images, especially fat suppression sequences 6. Appendix content Gas has been considered an exclusion criterion for AA, being synonymous with patency Appendicoliths are associated with a higher rate of complications

14. Atypical presentations of acute appendicitis Ascending retrocaecal (65%); pelvic(31%); transverse retrocaecal(2.5%); preileal ascending paracaecal (1%); and postileal ascending paracaecal (0.5%) It can also be located in atypical places such as the subhepatic or pelvic space, within an inguinal hernia ( Amyand’s hernia), within a femoral hernia(De Garengeot’s hernia) or even in the left lower quadrant Tip appendicitis - Appendicitis can start with obstruction of the lumen at a distance from the opening, so the inflammation can be limited to only the tip of the appendix. Appendicial duplication Stump appendicitis

15. The diagnostic key to locating the appendix in the different imaging modalities is to identify the ileum/ ileocaecal valve complex, The opening to the appendix is constant and is normally located 3 or 4 cm caudal to the ileocaecal valve, on the same side as the terminal ileum.

16. Diseases mimicking appendicitis Increase in the appendix lumen without appendicitis Appendiceal diverticulitis Appendiceal endometriosis Tumours of the appendix Reactive appendicitis

17. Complicated appendicitis Complicated appendicitis is best assessed with CT Phlegmon: inflammatory soft tissue mass surrounding the appendix Abscess Wall enhancement defects Extraluminal air Extraluminal appendicolith

18. Manifestations of complicated appendicitis Gangrenous appendicitis Pylephlebitis : ascending infection through the portomesenteric venous drainage, which can cause venous thrombosis and liver abscess Fistulas Diffuse peritonitis Other complications: complicated AA can cause obstructive uropathy or bowel obstruction secondary to involvement of the right ureter and terminal ileum, respectively

19. C0NCLUSION In children and pregnant women, ultrasound should be performed first, followed by MRI in uncertain cases. In adults, the strategy of initial ultrasound and CT only in inconclusive ultrasounds has been shown to have high diagnostic accuracy with a significant reduction in radiation exposure. Radiologists must be able to recognize atypical presentations and AA-mimicking appendiceal disease, and include signs of complicated AA in their report

20. UPDATES On ultrasound, the appendix is measured along its axial axis from serosa to serosa and is considered abnormal if it is greater than 7 mm This cut-off has a better positive predictive value than the 6-mm criterion originally suggested by Jeffrey et al. Even so, an appendix of 6−8 mm should be considered suspect according to some authors and the diagnosis supported by associated signs In CT and MRI, the cut-off should be higher as it is being measured without appendiceal compression, and considered abnormal when greater than 10 mm. A lumen of 7−10 mm is suspect, and associated signs should be sought to support the diagnosis