Artifacts, Pitfalls & Normal Variants

Pseudo-Pelvic Mass


"Pseudomass" due to reflections and shadowing from bowel within the pelvis

Sonogram of the same patient demonstrates air within bowel loops within the pelvis

Dermoids within the right ovary of another patient. Reflections from tissue (hair) within the dermoid are quite different.

Findings:

The image on the left demonstrates a "pseudomass" due to reflections from bowel gas anteriorly and reverberation artifact posteriorly (arrows). Unfortunately, the most misleading aspect of reflections from bowel gas within the pelvis is the "rounded" mass-like nature of the posterior artifact. Unfortunately, the concept of "dirty shadowing" from reflected air may theoretically simulate a dermoid tumor. In fact these sonograms are quite different and with experience will be correctly recognized. The echogenicity from dermoid tumors tends to be of two types: discrete shadowing from calcifications (bone or teeth) and more diffuse shadowing from hair. This shadowing tends to be gradual, still maintaining a solid appearance to the mass. If the reverberative nature of the strong reflections from bowel gas are not recognized often adjacent individual segments of bowel filled with air will be recognized (as in the middle scan). If there is still a difficulty, either having the patient return for a follow-up scan or x-ray of the abdomen, may clear up the difficulty.

 

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