A contrast blush is occasionally seen on abdominal CT in patients with solid organ injury. This represents active arterial extravasation from the injured organ. In most institutions, this is grounds for call interventional radiology to evaluate and possibly embolize the problem. The image below shows a typical blush from extravasation.
This thinking is fairly routine and supported by the literature in adults. However, it cannot be generalized to children!
Children have more elastic tissue in their spleen and tend to do better with nonoperative management than adults. The same holds true for contrast blushes. The vast majority of children will stop bleeding on their own, despite the appearance of a large blush. In fact, if children are taken to angiography, it is commonplace for no extravasation to be seen!
Angiography introduces the risk of local complications in the femoral artery as well as more proximal ones. That, coupled with the fact that embolization is rarely needed, should keep any prudent trauma surgeon from ordering the test. It should be reserved for cases where nonoperative management is failing, but hypotension (hard fail) has not yet occurred.
The only difficult questions is “when is a child no longer a child?” Is there an age cutoff at which the spleen starts acting like an adult and keeps on bleeding? Unfortunately, we don’t know. I recommend that you use the "eyeball test", and reserve angiography for kids with contrast extravasation who look like adults (size and body habitus).
Reference: What is the significance of contrast “blush” in pediatric blunt splenic trauma? Davies et al. J Pediatric Surg 2010 May; 45(5):916-20.