Periappendiceal hyperechoic structure on sonography: a sign of severe appendicitis

We retrospectively investigated the clinical importance of the periappendiceal hyperechoic structure (PHS) using sonography in patients with appendicitis, which may reflect the omentum encapsulating the inflammation or spread of inflammation over the omental and adjacent mesenteric fat.

We defined the positive finding of a PHS as a noncompressible and enlarged (>6 mm in its maximal outer diameter) appendix surrounded by the hyperechoic structure that was not visualized in the right lower quadrant on sonography. We compared this finding with surgical records and pathologic diagnosis in 25 patients who underwent an appendectomy for appendicitis.

Of 25 patients, there were 7 patients with positive PHS findings. The positive PHS rates were 100% (2 of 2), 29% (5 of 17), and 0% (0 of 6) for gangrenous, phlegmonous, and early appendicitis, respectively. There was a statistically significant difference by the Spearman rank test. The incidence rates of perforation (57% versus 6%), macroscopic purulent exudate or abscess (57% versus 6%), and prominent adhesion to the periappendiceal tissue (100% versus 22%) were higher in the patients with positive PHS findings.

The PHS may indicate the possibility of serious inflammation, and accurate diagnosis and appropriate treatment should be decided.