Diagnostic Ultrasound - Abdomen and Pelvis

Segmental Omental Infarction
Diagnoses: Abdominal Wall/Peritoneal Cavity
TERMINOLOGY
• Vascular compromise of greater omentum (may be primary
or secondary)
IMAGING
• Noncompressible focal echogenic fat at site of maximal
tenderness
• CECT demonstrates focal fat haziness or, more commonly,
a large (> 5 cm) nonenhancing heterogeneous omental
mass with fat stranding
• Central dot sign may be present (central
echogenic/hyperattenuating focus representing central
engorged or thrombosed vessel/hemorrhage)
TOP DIFFERENTIAL DIAGNOSES
• Acute appendicitis
• Acute cholecystitis
• Right-sided diverticulitis
• Epiploic appendagitis
KEY FACTS
PATHOLOGY
• Primary OI may result from venous channel kinking or
omental torsion (resulting in vascular compromise)
• Secondary OI may result from torsion due to: (a)
attachment to an acquired lesion (e.g., surgical scar and
neoplasm), (b) trauma, or (c) hernial incarceration
CLINICAL ISSUES
• Typical radiological appearances are diagnostic and
management is conservative
DIAGNOSTIC CHECKLIST
• Typical cross-sectional appearances with normal
appearances to adjacent structures
• Absence of symptoms and signs of sepsis
• Differentiate from more common causes of acute
abdominal pain (especially acute appendicitis and acute
cholecystitis)
• Most common in right side of abdomen
(Left) Transabdominal
ultrasound of the right upper
quadrant in a patient
presenting with acute rightsided
upper abdominal pain
shows an echogenic elliptical
mass deep to the anterior
abdominal wall . The
adjacent gallbladder appeared
normal (not shown). (Right)
Axial CECT of the same
patient shows haziness to the
omental fat in the right
upper quadrant corresponding
to the ultrasound abnormality.
Note the adjacent thin-walled,
normal-appearing gallbladder.
(Left) Coronal MPR from the
same patient shows omental
fat with haziness giving a
mass-like appearance. Note
the normal thin-walled
gallbladder. (Right) Follow-up
study after 3 months shows
interval improvement with
slow resolution of the
radiological changes.
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