acute appendicitis final.pptx

Studying appendicitis prevalent in Nepal

1. Case presentation Acute Appendicitis

2. 22 years male h/o pain in lower right iliac fossa Tenderness and rebound tenderness present

3. A blind ending, tubular, aperistaltic, non-compressible, hypoechoic tubular structure with wall to wall diameter of approx. 11.2mm noted in right iliac fossa.

4. Appendix - Anatomy The appendix arises from the posteromedial surface of the caecum, approximately 2-3 cm inferiorly to the ileocaecal valve, where the taena coli converge. It is a blind diverticulum, which is variable in length from 2-20 cm. The appendix lies on its own mesentery, the mesoappendix . The tip of the appendix can have a variable position within the abdominal cavity : -retro-caecal (65-70%) -pelvic (25-30%) -pre- or post- ileal (5%)

5. Acute appendicitis Acute appendicitis is the most common cause of acute abdominal pain requiring surgery Acute appendicitis is typically a disease of children and young adults with a peak incidence in the 2 nd  to 3 rd  decades of life pathogenesis of acute appendicitis is thought to relate to obstruction of its orific e

6. Appendicitis is typically caused by obstruction of the appendiceal lumen, with resultant build up of fluid, secondary infection, venous congestion, ischaemia and necrosis. Obstruction may be caused by: -lymphoid hyperplasia (~60%) -appendicolith (~33%) -foreign bodies (~4%) - Crohn disease or other rare causes, e.g. stricture, tumour , parasite

7. Imaging in Appendicitis In older clinical literature before routine cross-sectional imaging was available, laparotomy resulted in removal of normal, noninflamed appendices in 16% to 47% of cases (mean, 26 %) Also, perforation occurred in up to 35% of cases.

8. Plain X ray abdomen The presence of calcified fecoliths ( appendicoliths ) is the single most important sign of appendicitis seen plain x ray abdomen Generalized paralytic ileus may occur in cases of perforated appendicitis but pneumoperitoneum is rare .

9. Ultrasound Findings supportive of the diagnosis of appendicitis include : -Aperistaltic, noncompressible , dilated appendix ( >6 mm outer diameter) -Appendicolith -Distinct appendiceal wall layers -Echogenic prominent pericaecal fat -Periappendiceal fluid collection -Target appearance (axial section)

10. Puylaert’s technique of Graded compression Allows normal and gas filled loops of gut to be displaced from the field of view or compressed between the layers of musculature of the anterior and posterior abdominal wall. patient is able to provide input as to the point of maximal tenderness, which is often useful in focusing the examination in the correct area When a patient can self localize the site of maximal tenderness, there is a significant sonographic finding at this site in 94% of cases

11. Other maneuver Turning the patient into the left lateral decubitus position maybe helpful in visualizing the retrocecal appendix . Transducers with a variable short focal zone and a frequency of 5–9 MHz have been recommended .

12. Sonographic studies of normal individuals show that up to 23% of normal patients have appendicular sizes >6 mm

13. early acute appendicitis-catarrhal stage-five layers can be identified 1) A central, thin hyperechoic line representing the collapsed lumen and mucosal lining 2) Hypoechoic layer (2–3 mm) representing the edematous lamina propria and muscularis mucosa 3) Hyperechoic sub mucosa ( 2–3 mm ) 4) Hypoechoic muscular layer (2–3 mm ) 5) Outer most thin hyperechoic line representing the serosa

14. In the later suppurative stages, the lumen of the appendix gets distended with pus/fluid and there may be an increase in the thickness of the submucosa and muscular layer in the range of 3–6 mm . Appendicoliths are seen as bright, echogenic foci with clean distal acoustic shadowing.

15. Inflammatory change in the adjacent fat appears bright and noncompressible and is a sonographic clue to the presence of appendicitis in doubtful cases. Enlarged mesenteric lymph nodes may be identified.

16. An asymmetric thickening of the appendiceal wall with a focal/circumferential lack of visualization of the echogenic submucosa indicates perforation of the inflamed appendix. An appendiceal mass is seen as a complex paracecal mass of mixed echogenicity and thickened paracecal fat.

17. In cases of appendicitis, the presence of hyperaemia in the appendiceal wall and adjacent mesoappendix is a sensitive indicator of inflammation and can be well demonstrated on colour Doppler.

18. The contribution of Doppler US is most evident in cases of equivocal grey scale US examination in which it is uncertain as to whether the imaged appendix is inflamed or normal.

19. pitfalls The most important cause for a false negative result is overlooking of the appendix . Other causes are obesity and a retrocecal position of the appendix Peritonism may prevent graded compression in patients with perforation, or the dilated, air filled loops of adynamic ileus can hide the appendix from view .

20. The appendix may be relatively thickened in cases of perforated peptic ulcer or sigmoid diverticulitis and a false positive diagnosis is possible. In some cases the terminal ileum may be misinterpreted as the inflamed appendix

21. CT The most commonly used CT technique for studying the appendix is a scan of the entire abdomen and pelvis after both oral and IV administration of contrast material Disadvantage of this technique is the time taken for the oral contrast to reach the cecum, which is essential for best results. CT is highly sensitive (94-98%) and specific (up to 97%) for the diagnosis of acute appendicitis and allows for alternative causes of abdominal pain to also be diagnosed.

22. Periappendiceal inflammation, including stranding of the adjacent fat and thickening of the lateroconal fascia or mesoappendix . - Extraluminal fluid -Inflammatory phlegmon -Abscess formation -Appendicolith may also be identified

23. In the absence of secondary changes, a luminal diameter of 9 mm has been advocated as the threshold size for appendicitis. Linear fat stranding, local fascial thickening and subtle clouding of the mesentery are characteristic findings of periappendiceal inflammation in nonperforated appendicitis

24. Caecal bar sign The caecal bar sign is a secondary sign in acute appendicitis. It refers to the appearance of inflammatory soft tissue at the base of the appendix , separating the appendix from the contrast-filled caecum.

25. Arrowhead sign The arrowhead sign refers to the focal caecal thickening centered on the appendiceal orifice, seen as a secondary sign in acute appendicitis. The contrast material in the cecal lumen assumes an arrowhead configuration, pointing at the appendix. The arrowhead sign is applicable only when enteric contrast distends the caecum.

26. MRI Magnetic resonance imaging (MRI) is not routinely advocated in cases of suspected appendicitis, it can be useful in cases where sonography is equivocal and CT is not possible or contraindicated such as pregnant women On MRI acute appendicitis is best seen in T2W sequences in the axial and coronal planes.

27. T2W images are superior to T1W images because of better visualization of the bright signal intensity of inflammatory change associated with acute appendicitis On T2W imaging , the thickened appendiceal wall is seen as a slightly hyperintense ring with a markedly hyperintense centre representing intraluminal fluid

28. The cutoff threshold of the appendix is the same as for CT . Periappendiceal inflammation gives a marked hyperintense signal . Appendicoliths are difficult to demonstrate on MRI as they are seen as intraluminal structures without signal intensity on all sequences.

29. Complication of acute appendicitis

30. Complication- perforation If appendicitis is allowed to progress, portions of the appendiceal wall eventually become ischemic or necrotic and the appendix perforates. CT findings— extraluminal air, extraluminal appendicolith, abscess, and a defect in the enhancing appendiceal wall—allows excellent sensitivity (95%) and specificity (95%) for perforation in patients with known appendicitis who underwent preoperative CT. In that study, the individual finding with highest sensitivity was a mural enhancement defect (64%).

31. 32-year-old man with acute appendicitis. Unenhanced CT shows appendicolith (arrowhead), periappendiceal fat stranding (black arrows), lateral conal fascia thickening (white arrow), and periappendiceal fluid. Perforation was confirmed on surgery

32. Abscess formation Abscess is the most frequent complication of perforation. The abscess remains localized if periappendiceal fibrinous adhesions develop before rupture. CT shows a loculated , rim- enhancing fluid collection that may have mass effect on adjacent bowel loops. If the abscess is large (> 4 cm), percutaneous drainage followed by delayed appendectomy is the preferred treatment .

33. 47-year-old man with periappendiceal abscess. Helical CT after IV contrast injection shows periappendiceal abscess extending into psoas muscle (arrowheads).