Device selection and procedural guidance for percutaneous ductal closure strongly rely upon angiographic and echocardiographic imaging. Current literature recognises 2D echocardiography as an essential tool for diagnosis and assessment but does not define a consistent methodology to optimise ductal measurement. There is little research comparing echocardiography with gold standard angiography for ductal measurement. Proving 2D echocardiographic ductal measurement to be equivalent to angiography could pave the way for its use as the primary modality in image guidance for percutaneous closure of the ductus. This was a retrospective study of 100 consecutive paediatric patients who underwent percutaneous ductal closure. Echocardiographic images were studied to determine ductal (a) morphology (b) dimensions (length, aortic ampulla, pulmonary end, minimum diameter) (c) size of device that would be appropriate for closure. These data were compared to corresponding measurements generated by angiographic images. Inter and intra-observer ratings were calculated to assess levels of agreement. There were significant differences between the imaging methods in classifying the morphological sub-type and ductal measurements (p < 0.005), except for length which was not found to be significantly different between modalities. Prediction of device selection from angiographic images showed excellent agreement (weighted k = 0.81). Predictions based on echocardiographic images showed a poor level of agreement (weighted k = 0.14). We found poor correlation between echocardiography and angiography for measurement, morphological assessment and device selection. Based on our findings, percutaneous arterial duct occlusion without angiographic guidance in this age group cannot be advocated.