Omental infarct versus appendicitis

Joseph P. Gerding, M.D.

Olya Polishchuk

Jessica Casey

Eugene Anandappa, M.D.

Children's Memorial Hospital

Abstract

3 patients with right lower quadrant pain

Keywords

Omental infarct, appendicitis, ultrasound, CT, 160


Publication Date: 2006-01-20

History

3 patients with right lower quadrant pain

PATIENT 1: 7 year old female with right lower quadrant pain for 1 week and a fever.

PATIENT 2: 4 year old male with low-grade fever and abdominal pain

PATIENT 3: 16 year old female with abdominal pain and vomiting

Findings

PATIENT 1:

US: Nonspecific echogenic structure at the site of pain in the right lower quadrant. No appendicitis was seen.

CT: Moderate to large amount of fatty inflammatory stranding in the right anterior lower quadrant.

PATIENT 2:

CT: In the right lower quadrant there is a tubular structure originating from the cecum which is enlarged consistant with an inflamed appendix. Additionally, there is a 5 mm high density appendicolith.

PATIENT 3:

US: Within the right lower quadrant, there is an enlarged tubular structure with thickened walls and vascularity within the walls. It is noncompressible.

Diagnosis

PATIENT 1: Segmental omental infarction

PATIENTS 2&3: Appendicitis

Discussion

SEGMENTAL OMENTAL INFARCT

Segmental infarction of the greater omentum is a rare cause of acute abdomen. Its cause is unknown. Theories suggest that an anomalous arterial supply renders the omentum susceptible to infarction by kinking from increased intraabdominal pressure or vascular congestion related to large meals. Fifteen percent of cases occur in children. Studies suggest that obesity may be a risk factor, possibly due to fat deposition in the omentum that outstrips its blood supply.

Patients present with pain and tenderness in the right abdomen, typically the right lower quadrant. They may also have peritoneal signs, an increased white blood cell count, and a low grade fever. Clinically, the signs and symptoms are indistinguishable from acute appendicitis, and this usually is the clinical diagnosis.

Ultrasound will show a large, solid, hyperechoic, and non-compressible mass. Although sensitive, it is not specific. CT will demonstrate a heterogeneous fatty mass anterior to the colon, adherent to inflamed peritoneum, which contains strands of soft tissue attenuation. It occurs on the right side in 90%. The appendix will be normal. It can be differentiated from epiploic appendagitis by its larger size, heterogeneity, greater mass effect on adjacent bowel wall, typical right-sided location, absence of the "ring sign", and more obvious peritoneal thickening and adherence. Epiploic appendagitis is usually on the left side, smaller, and demonstrates a "ring sign".

Patients are treated conservatively and will recover spontaneously.

APPENDICITIS

Appendicitis in children can be diagnosed with an ultrasound or CT. CT is useful in larger patients or when alternative diagnosis are being considered. An appendix larger than 6 mm, nonfilling with oral or rectal contrast, appendicolith, and surrounding soft tissue stranding are all findings suggestive of appendicitis. CT is also useful for evaluation of perforated appendicitis or adjacent abscesses.

Ultrasound of the right lower quadrant should demonstrate completely compressible bowel against the psoas muscle. A noncompressible tubular structure greater than 6 mm in the right lower quadrant is consistent with appendicitis. Associated findings include increased vascularity in the wall and adjacent fluid collections.

References

  1. Grattan-Smith JD et al. Omental infarction in pediatric patients. AJR, 2002;178:1537-9.
  2. Mcclure MJ et al. Radiological features of epiploic appendagitis and segmental omental infarction. Clincal Radiology, 2001;56:819-27.
  3. Paroz A et al. Idiopathic segmental infarction of the greater omentum: A rare cause of acute abdomen. Journal of Gastrointestinal Surgery, 2003;7:805-8.
  4. Puylaert JBCM. Right-sided segmental infarction of the omentum: Clinical, US, and CT findings. Radiology, 1992;185:169-72.
  5. Swischuk, L. E., EMERGENCY IMAGING OF THE ACUTELY ILL OR INJURED CHILD, Lippincott Williams and Wilkins, 2000, 177-193.
  6. Varjavandi V et al. Omental infarction: Risk factors in children. Journal of Pediatric Surgery, 2003;38(2):233-5.

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