[en] To compare hydrocolonic sonography with histopathology for diagnosing children with symptoms highly suggestive of Hirschsprung disease (HD). In this prospective study, patients presenting refractory constipation highly suggestive of HD underwent hydrocolonic sonography with retrograde infusion of saline into the colon. The dilated segments, narrowed segments, luminal diameter ratio, transition zone (TZ), thickening, and blood perfusion of the upstream bowel were evaluated. The sensitivity and specificity of combined and single parameters were determined in comparison with biopsy. One hundred and three children were included in this study; 49 were confirmed to have HD. The luminal diameter ratio showed superiority over other parameters. An area under the curve (AUC) of 0.969 (95% confidence interval [CI]: 0.936-1.000) and a cutoff value of 1.51 were established by receiver operating characteristic (ROC) curve analysis of the luminal diameter ratio (sensitivity: 89.8%; specificity: 96.3%). By combining the luminal diameter ratio as the major criterion with two minor criteria, hydrocolonic sonography showed the same sensitivity (91.8%) and better specificity (96.3% vs 87%) than contrast enema, but this difference was not statistically significant (p = 0.063). Consistency analysis showed a kappa value of 0.825 (p < 0.001), indicating excellent agreement between hydrocolonic sonography and contrast enema. Hydrocolonic sonography is a valuable diagnostic tool with both high sensitivity and specificity for HD diagnosis, allowing morphological and vascular assessments of the colon, and correlates well with contrast enema. In the appropriate setting, hydrocolonic sonography may be an alternative screening method for HD in a large group of children with constipation. Key Points Hydrocolonic sonography is a simple, well-tolerated diagnostic tool with both high sensitivity and specificity for HD diagnosis. Hydrocolonic sonography allows morphological and vascular assessments of the colon, and correlates well with contrast enema. Hydrocolonic sonography is a possible alternative modality for paediatric patients highly suggestive of HD.