Accuracy of Transperineal Ultrasonography for Assessing Rectal Lesions in Paediatric Ulcerative Colitis: A Prospective Study.

BACKGROUND AND AIMS: Transabdominal ultrasonography [TAUS] appears comparable to colonoscopy for evaluating ulcerative colitis [UC] activity, but it has low accuracy in rectal evaluation. In this study, the accuracy of transperineal ultrasonography [TPUS] for evaluating rectal activity was compared to that of colonoscopy in paediatric UC cases. METHODS: Faecal calprotectin [FCP] values and TPUS and colonoscopic findings were compared prospectively in paediatric UC cases. Rectal wall thickening [RWT] and rectal wall flow [RWF] on power Doppler evaluated by TPUS were compared with the colonoscopy findings and were also measured on TAUS and assessed for the concordance rate of each finding. RESULTS: Thirty Mayo endoscopic sub-score [MES] 0-1 UC cases and 57 MES 2-3 UC cases were enrolled. FCP, RWT and RWF showed significant differences between the two groups [p < 0.05]. RWT and RWF were independent predictors of UC endoscopic activity, showing sensitivity of 95.8% and specificity of 100% with RWT ≥ 4.5 mm and positive RWF. The concordance rates between TPUS and TAUS findings in MES 2-3 were moderate to fair, whereas those in MES 0-1 were fair to poor. The concordance rates between ultrasonic examiners were good for both TAUS and TPUS. CONCLUSIONS: TPUS may evaluate rectal activity of UC with accuracy comparable to endoscopy. If accurate ultrasonic screening for the total colon can be performed by TPUS and TAUS, repeated evaluation of short-term treatment response may be possible.