In a thrilling finale to the race, Scowen and her partner Nick Beighton, were fighting for bronze right up to the finish line but were edged out by the Americans in lane 2 by just over two tenths of a second.
China won an emphatic gold in 3 minutes 57.63 seconds followed by the French in silver and the USA bronze in 4:05.56, just 0.21 seconds ahead of Scowen and Beighton.
Scowen, who went to Ryeish Green School, said: "I'm really proud of the performance we put in but gutted it wasn't quite good enough."
Even though she missed out on bronze, she was remained positive.
"To put in three good performances back to back over three days, I'm just really proud of everything that we've put together.
"I'm gutted but I'm sure in a few days, I'll be really pleased."
It was the pair's debut in such a high profile competition after pairing up a year and a half ago.
FULL INTERVIEW WILL BE IN THURSDAY'S NEWS