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A computed tomography phantom study of foam earplugs: Uncommon but potentially hazardous foreign body ingestion in
Li-Sheng Hsu1, Ju-Bei Yen, Shie-Shan Wang
1Department of Diagnostic Radiology, Chang Gung Memorial Hospital Department of Physical Education, Health and Recreation, National Chiayi University, Chiayi, Taiwan Chang Gung University College of Medicine, Taoyuan, Taiwan Department of Pediatrics Department of Pediatric Surgery, Chang Gung Memorial Hospital, Chiayi Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, Taiwan.
Insights
Foam earplugs (FEPs) ingestion in infants can cause bowel obstruction. This study details FEP imaging characteristics on CT scans, aiding diagnosis and preventing surgical misidentification.
Area of Science:
- Pediatric Radiology
- Gastrointestinal Imaging
- Foreign Body Ingestion
Background:
- Foreign body ingestion is common in children, but foam earplug (FEP) ingestion is a novel presentation.
- A 7-month-old infant with small bowel obstruction was diagnosed with FEP ingestion.
Observation:
- Computed tomography (CT) phantom studies examined FEPs in various dry, wet, and compressed states.
- FEP densities varied from -843.5 HU (dry) to 0.76 HU (wet), with heterogeneous patterns observed.
Findings:
- FEPs exhibit density changes based on hydration and compression, potentially mimicking fatty lesions or being obscured when fully wet.
- Dry FEPs have a distinct density (-843.5 HU) observable with appropriate CT window settings.
Implications:
- Radiologists must recognize CT features of FEPs to avoid misdiagnosis and aid surgical planning.
- Surgeons should be aware of FEPs' soft texture to prevent intraoperative oversight.
Abstract:
Ingestion of a foreign body is common among children. However, ingestion of foam earplugs (FEPs) has not been reported previously. A 7-month-old female infant presented with small bowel obstruction, which was finally proved to be a case of FEP ingestion.Computed tomography (CT) phantom study was performed to examine the imaging features of FEPs. We studied the following dry and fully wet FEPs, FEPs squeezed in pure water to varying degrees, and FEPs with different degrees of compression in the dry and wet states from day 0 to 6 and all scanned with a CT scanner.The density of a dry FEP is -843.5 ± 4.5 Hounsfield units (HU) and it increases to 0.76 ± 9.3 HU when fully wet. The densities of FEPs ranged from -844.2 to 1.0 HU with different water/air ratios, and some showed a heterogeneous geographic pattern. The densities of FEPs increase due to compression and gradual water absorption.FEPs can be potentially hazardous objects to children. Owing to the special foam structure of the FEP, it can mimic a fatty lesion if the density ranges from -100 to -50 HU; moreover, it can hide in the water if fully wet. However, it should not be mistaken as air, as the density of a dry FEP is -843.5 HU, and the contour can be observed if the window level is set appropriately. Because of its soft texture, the surgeon should be careful not to miss an FEP during the operation. Moreover, radiologists should be familiar with the CT features of FEPs so that they can be identified before surgery.
