Guidelines Needed for CT After Inconclusive Abdominal Ultrasound

About 33 percent of CT examinations performed following an inconclusive abdominal ultrasound have positive findings, and most are useful in diagnosing renal lesions, say researchers from Massachusetts General Hospital in Boston.

For a study presented this week at the American Roentgen Ray Society Annual Meeting in Vancouver, Canada, researchers reviewed findings from 449 patients who had undergone an abdominal ultrasound that was inconclusive, followed by a CT scan. The results showed that 32.9 percent of the follow-up CTs had positive findings, 42.7 percent had no significant positive findings, 12 percent had incidental findings unrelated to the reason for the scan, and 11.7 percent were inconclusive.

Where the follow-up scan was the most useful was in diagnosing renal lesions, where the positivity rate was 87.5 percent for renal cysts and 81.8 percent for renal stones, the two most common indications for follow-up CT scans, researchers found.

“While only about 33 percent of the CT examinations had positive findings, it doesn’t mean that the other CT exams were not as valuable as sometimes even negative exams add a lot to patient management,” said Supriya Gupta, MD, one of the study authors.

However, researchers said, standardized guidelines for the use of follow-up CT scans do need to be developed because of the cost and radiation implications.