Computed tomographic colonography may be used for primary colorectal cancer screening with a small polyp size threshold.
This technique may define a computed tomographic colonography study as positive.
If this is the case, a substantial portion of all colonoscopies performed annually will be to follow up positive computed tomographic colonography examinations.
Moreover, the majority of positive computed tomographic colonography examinations would be false positives.
Dr Chin Hur and colleagues from Massachusetts undertook a case-control study.
The researchers assessed whether colonoscopy examinations resulting from false positive studies would take longer to complete than negative screening colonoscopies.
Endoscopic records of a large, urban hospital were reviewed.
The team identified all patients who had either a positive barium enema study or flexible sigmoidoscopy and a negative follow-up colonoscopy.
|False positive colonoscopies required 61% more active time to complete|
|Clinical Gastroenterology & Hepatology|
The patients with a negative follow-up examination were used as surrogates for computed tomographic colonography false positive cases.
For each of the 28 false positive patients identified, 2 screening colonoscopies performed by the same endoscopist within the same time period were noted.
These were used as matched controls.
The research team performed a 2-way analysis of variance test to assess for differences in time to complete colonoscopies between these 2 groups.
The researchers found that false positive colonoscopies took an average of 24 minutes to complete.
Although negative screening colonoscopies took 15 minutes, false positive colonoscopies required 61% more active time to complete.
The team noted that this highly statistically significant difference persisted with subset analyses that only included barium enema.
The significant differences also persisited when the analysis only included flexible sigmoidoscopy cases, and when fellow or surgeon cases were excluded.
Dr Hur's team commented, “False positive colonoscopies take longer to perform than negative screening colonoscopies.”
“If computed tomographic colonography is implemented as the primary modality for colorectal cancer screening, these false positive examinations could comprise a substantial percentage of the colonoscopies performed.”
This could potentially leading to a significant decrease in endoscopic productivity.”