Ultrasound visualization of ingested tablets: a pilot study

To evaluate the ability of ultrasonography as a radiographic technique to visualize ingested tablets in the human stomach.

Prospective, ultrasonographer-blinded, pilot study.

Tertiary care medical center.

Fifteen healthy adults (12 male, 3 female; mean age 35.5 yrs).

After fasting for at least 12 hours, subjects were randomized to either ingest a total of 10 tablets (four acetaminophen, four ibuprofen, and two multivitamin tablets) with 500 ml of water or to drink 500 ml of water alone (control group).

Nine subjects were randomized to the group taking the tablets and six to the control group. Within 30 minutes after ingesting the tablets with water or the water alone, each subject underwent ultrasonography 2 times by two respective blinded ultrasonographers (emergency department physicians who were experienced with the ultrasound technique). Each performed the radiographic technique in isolation of the other ultrasonographer so as not to influence each other's interpretation. They recorded whether or not they thought tablets were visible. One ultrasonographer was correct for 14 (93%) of the 15 subjects, but the other ultrasonographer was correct for only 6 subjects (40%). Interobserver agreement was assessed, with no agreement found between the two ultrasonographers (Cohen κ coefficient -0.25 [95% confidence interval -0.7-0.2]). The ultrasonographers also found six false positives (no drugs present in the stomach but incorrectly identified as present by the ultrasonographer) and four false negatives (tablets present in the stomach but not identified by the ultrasonographer).

Our results do not support the application of ultrasonography to determine the presence or absence of tablets in an individual's stomach after an acute poisonings. We did show that, similar to other radiologic techniques (e.g., projection radiography), the absence of tablet visualization does not exclude their presence. However, the ultrasonographers also found several false positives. Thus, further studies are needed with larger numbers of both subjects and ultrasonographers to elucidate the potential benefit of ultrasonography in individuals who experience acute poisoning.