Sonography of abdominal pain in children: appendicitis & its common mimics

Summary of this excellent article
Normal appendix

blind-ending, tubular, and nonperistalsing segment of bowel
arising from cecum
no surrounding mesenteric edema

Doppler for hyperemia
periappendiceal fluid
periappendiceal inflammation (echogenic change): reliable indicator of appendicitis

Diagnosis of appendicitis 
Probe: curved then linear for better resolution and compression
Diameter cutoff: wall-to-wall 6 mm
(7 mm for no secondary signs of inflammation, such as lymphoid hyperplasia or fecal impaction of appendix)
Graded compression: non-compressible
(Pitfall: muscle guarding, appendix slide away, operator technique, patient obesity and transducers)

Sonography for Appendiceal perforation: Sensitivity 86%
Echogenic submucosal disruption
Complex periappendiceal fluid

Benefit of sonography as first line
reliable in skilled hands
no ionizing radiation exposure

Mesenteric lymphadenitis 
the most common appendicitis mimic
Lymph node size: > 10 mm
Doppler: hyperremia
Compression: tender

the most common cause of bowel obstruction for age < 5 years
triad (<40%): colicky abdominal pain, palpable mass, bloody stool
sonography: imaging modality of choice
Sensitivity & Specificity: about 98%
Target or pseudokidney signs (echogenic mucosa-hypoechoic muscularis-echogenic serosa)
Sandwich signs: outer intussuscipiens & inner telescoping intussusceptum
< 1.5 cm (small bowel, ileoileal , most resolved spontaneously)
> 2.5 cm (fatty core or lymph nodes, need emergent reduction)
If presence with diffuse small bowel wall thickening
==> consider lymphoma or Henoch-Schonlein Purpura
Role of echo: diagnosis & hydrostatic reduction

Meckel diverticulum
the most common congenital GI tract anomaly
related to intussusception, bleeding or diverticulitis (appendicitis mimic)
Nuclear medicine Meckel scan: Sens 81%; Speci 96%

Ovarian torsion
most common on right side (appendicitis mimic)
Size: most important factor
General rule: unlikely for smaller than 5 cm 
Doppler flow is not reliable

Sonography of Abdominal Pain in Children

Appendicitis and Its Common Mimics ( by TR Sanchez et al.)



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