Diagnostic performance of ultrasound without any colon preparation for detecting colorectal polyps in pediatric patients

Background There are limited data on the sensitivity, specificity and accuracy of ultrasound for detecting colorectal polyps in children and young adults. Objective To evaluate the diagnostic accuracy of ultrasound, without any colon preparation, for detecting colorectal polyps in pediatric patients and to determine the causes of false-negative results. Materials and methods We included 74 children with clinical signs like rectal bleeding, abdominal pain or diarrhea who underwent both ultrasound and colonoscopy. We evaluated the diagnostic performance of ultrasound for detecting colorectal polyps before colonoscopy, which served as the reference standard. We used Fisher exact and Student's t-tests for statistical analyses. Results Fifteen pediatric patients were diagnosed with colorectal polyps in the transverse (n=3), descending (n=1) and sigmoid (n=6) colon, and rectum (n=5) by colonoscopy. The sensitivity, specificity and accuracy of ultrasound to detect colorectal polyps were 47% (7/15, 95% confidence interval [CI] 21-73%), 100% (59/59, 95% CI 94-100%) and 89% (66/74, 95% CI 80-95%), respectively. The volume (mean +/- standard deviation) of polyps not detected by ultrasound was significantly smaller than that detected (270 +/- 380 mm(3) vs. 4,600 +/- 3,900 mm(3), P=0.0124). We observed a significant difference in the location between the polyps detected and not detected by ultrasound (rectal/non-rectal=0/7 vs. 5/3, P=0.0256). No significant age or gender difference was observed. Conclusion The accuracy for detecting colorectal polyps by ultrasound was 89% (95% CI, 80-95%) in our cohort. Polyps found in the rectum and relatively smaller polyps accounted for several false-negative cases.