Diagnostic Imaging: Barium Enema: Accuracy
Barium enema was formerly the primary diagnostic modality used to evaluate for suspected appendicitis.
Non-filling of the appendix was considered to be a positive sign for appendicitis; this finding is also present in 5 - 10 % of normal patients (17).
The ability to exclude appendicitis requires visualization of the entire appendix(13).Filling of the appendix up to its bulbous tip occurs in only 69 - 77% of all normal cases (18). However it is difficult to differentiate complete from incomplete filling of the appendix on barium enema examination. The normal appendix has a concave tip. Barium enema short of this finding does not allow unequivocal exclusion of appendicitis(18).
Identifying a mass in conjunction with a normal appendix is rare in appendicitis(18).In the proper clinical context, the vast majority of patients who demonstrate incomplete or non-filling of the appendix accompanied by extrinsic mass effect on the cecum will be found to have appendicitis . Reported accuracy's of barium enema examination for suspected appendicitis have been as high as 91.5% (19).
Mass effect on the cecum are ancillary findings supportive of, but not specific for, appendicitis (18).
Non-acute disorders such as Crohn's disease, appendiceal mucocele, and cecal endometriosis can mimic appendicitis on barium enema due to their similar presentations with mass effect upon the cecum (20).
Diagnostic Imaging: Barium Enema: Findings in Appendicitis
Non-filling of the appendix and partial filling of the appendix is consistent with the hypothesis that luminal obstruction is an important factor in the cause of appendicitis(5).
Irregularity or nodularity of the appendix suggests mucosal edema caused by acute inflammation and is a nonspecific finding seen also with Crohn's disease.
Mass effect on the cecum and adjacent small bowel The cecal contour defect is due to cecal spasm and /or mass effect from the inflamed appendix, mesoappendix, adjacent edematous omental tissue, and/or in some cases a frank abscess associated with appendicitis.The mass effect can resemble the "coiled-spring" appearance of intussusception in the cecum at the site of origin of the appendix (14).