Appendicitis is a condition wherein the patient feels a pain in the right lower quadrant of the abdomen. It is characterized by the inflammation of the appendix. The diagnosis of appendicitis is made final through ultrasound. However, several conditions or diseases may mimic or simulate the ultrasound result of appendicitis; these diseases can also mimic appendicitis on clinical grounds and clinical presentation causing a pitfall in the diagnosis. Deeper interpretation of their ultrasound result can however establish an accurate diagnosis.
Ultrasound result of appendicitis shows an inflamed appendix which has a diameter larger than 6 mm. A normal appendix can develop reactive inflammation leading to enlargement in cases when there is an adjacent lesion. Conditions associated with these are the following:
1. Crohn’s disease
Clinically characterized by thickening of the ileum, cecum and appendix, which is similar to acute appendicitis. These two conditions are differentiated in ultrasound, severe thickening of the terminal ileum and cecum while only moderate thickening in the appendix is noted in Crohn’s disease while in appendicitis there is a marked thickening in the appendix wall and only mild in both terminal ileum and cecum.
2. Perforated peptic ulcer
Clinical symptoms are the same with appendicitis which is the pain in the lower right quadrant brought about by the accumulation of the gastric contents to this part of the abdomen and may also cause thickening of the appendix wall. Ultrasound shows a large accumulation of fluid in the abdominal cavity when the patient is in a certain position.
3. Appendiceal tumors
Cystoadenoma and carcinoid may cause enlarged appendix due to the growth of the tumor or by the obstruction of the appendiceal lumen which results to mucus accumulation. Tumor can be seen during ultrasound as mass but no inflammation signs on the lower right quadrant as seen in appendicitis.
4. Cecal carcinoma
This condition can clinically simulate or mimic appendicitis by presenting as a painful mass or secondary to perforation. However in ultrasound, cecal carcinoma can be seen as a solid and uncompressible mass at the cecal pole. This mass or tumor may cause obstruction in the appendix accumulating mucus.
5. Gynecologic conditions such as Tuboovarian abscesses / Pelvic inflammatory disease / Ovarian cyst
This condition may cause acute pelvic pain often simulating appendicitis. Tuboovarian abscesses can show extrinsic inflammation which is situated adjacent to the appendix causing thickening of the some parts of the appendix wall. But, this can be differentiated due to the echogenic submucosal ring of the appendix still being intact and there is the absence of appendicolith which is a calcified deposit and a causative agent of appendicitis.
This is the process of stone formation in the kidney, bladder and urethra or the urinary tract. The symptom can be clinically the same as appendicitis, right lower quadrant pain. The pain caused by the obstruction of the ureteral stone. This is diagnosed accurately by unenhanced CT.
7. Perforated acute cholecystitis
Local peritonitis caused by the descending leakage of bile along the paracolic gutter also causing the thickening of the appendix wall. However, ultrasound will differentiate this from appendicitis as cholecystitis has free fluid in the abdominal cavity.