Mimics of Appendicitis: Alternative Nonsurgical

Diagnoses with Sonography and CT

OBJECTIVE To illustrate the imaging features of

alternative nonsurgical disorders in patients presenting with clinical signs of appendicitis.

Normal and Inflamed Appendix

Normal appendix 1. Maximum outer diameter : 6mm 2. Homogeneous noninflamed fat 3. Compressible on US 4. Often contains intraluminal gas

Inflamed appendix 1. Outer diameter : ≥6mm 2. Surrounded by hyperechoic inflamed fat on US 3. Extramural changes with fat stranding on CT 4. Presence of an appendicolith 5. Cecal apical thickening 6. Hypervascularity of the appendix wall on color Doppler

sonography

Normal appendix

Inflamed Appendix

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract Gastrointestinal Tract

1. Mesenteric adenitis2. Infectious enterocolitis3. Epiploic appendages4. Omental infarction5. Right-sided colonic diverticulitis6. Crohn’s disease7. Ileocecal intussusception

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract1. Mesenteric adenitis

① The second most common cause of RLQ pain after appendicitis

② US & CT : Cluster of enlarged mesenteric lymph nodes and no other abnormalities

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract2. Infectious enterocolitis

① Bacterial ileocecitis caused by Yersinia, Campylobacter, or Salmonella spp.

② US & CT : Mural thickening of the terminal ileum and cecum without inflammation of the surrounding fat and moderate mesenteric adenopathy

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract3. Epiploic appendagitis

① Epiploic appendage may undergo torsion and secondary inflammation.

② US & CT : An inflamed fatty mass adjacent to the colon containing a characteristic hyperattenuating ring of thickened visceral peritoneal lining

Occasional dense central focus caused by a thrombosed vessel or hemorrhagic changes on CT.

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract3. Omental infarction

① Pathophysiology and clinical presentation similar to that of epiploic appendagitis Both have a similar benign natural history

② CT : A cakelike inflamed fatty mass larger than in epiploic appendagitis and lacking a hyperattenuating ring

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract4. Right-sided colonic diverticulitis

① In comparison with sigmoid diverticula, right-sided colonic diverticula are usually true diverticula ⇒ Explain the essentially benign self-limiting character of right-sided diverticulitis

② US & CT : Inflammatory changes in pericolic fat Segmental thickening of the colonic wall at the level of an inflamed diverticulum

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract5. Crohn's disease

① Up to one-third of patients with ileocecal Crohn's disease present with initial symptoms so acute that they are misdiagnosed as appendicitis

② US & CT : Transmural bowel wall thickening, often predominantly of the submucosal layer, with frequent inflammatory changes of the surrounding fat in the acute active phase.

Nonsurgical Mimics of Appendicitis : Gastrointestinal

Tract6. Ileocecal intussusception

① Peak age between 3 and 9 months② Enlarged mesenteric lymph nodes or

lymphoid hyperplasia of the distal ileum often acts as a lead point for intussusception

③ US : A bowel-within-bowel configuration with a targetlike mass on sonography consisting of multiple concentric rings related to the invaginating layers of the bowel wall

Nonsurgical Mimics of Appendicitis : Genitourinary Tract Genitourinary Tract

1. Pelvic inflammatory disease2. Hemorrhagic functional ovarian cyst3. Urolithiasis

Nonsurgical Mimics of Appendicitis : Genitourinary Tract

1. Pelvic inflammatory disease ① The imaging findings vary according to

the severity of the disease and may be normal in early conditions.

② US & CT : Enlargement of the internal genital organs with indistinct contours and free pelvic fluid in more advanced stage.

Nonsurgical Mimics of Appendicitis : Genitourinary Tract

2. hemorrhagic ovarian cyst ① Frequent cause of lower abdominal pain

in the pubertal population ② US & CT : A complicated cyst on

sonography and a high-attenuation adnexal mass on unenhanced CT

Nonsurgical Mimics of Appendicitis : Genitourinary Tract

3. Urolithiasis① US & CT : Unenhanced CT is more

accurate in detecting ureteral stones than sonography

Hydronephrosis and a hydroureter as signs of obstruction

Nonsurgical Mimics of Appendicitis : Musculoskeletal

Tract1. Rectus sheath hematoma

① Easy to diagnose in patients presenting with a painful palpable mass under anticoagulant therapy

② Small nonpalpable hematomas can clinically masquerade as appendicitis

③ US & CT : Hemorrhagic mass within the sheath of the rectus abdominis muscle

CONCLUSION A correct imaging diagnosis of these

alternative disorders may have a major impact on patient management because it prevents an unnecessary operation or hospitalization.