Leicester Tigers back Scully started on the wing for the Eagles, who came from behind at half-time to win through tries from Eric Fry, Mike Petri, Shalom Suniula and Andrew Suniula.
The teams entered the second leg of the RWC Qualifier level after last weekend’s 27-27 draw at Estadio Charrua in Montevideo, but the Eagles had home advantage and the backing of a 6,000-plus crowd at Kennesaw State University, Georgia.
USA were 13-3 down at the end of the first half after being the masters of their own downfall, a series of handling errors seeing them squander good field position in the early exchanges.
Things went from bad to worse when Andrew Suniula was sent to the sin-bin following an incident with Uruguay replacement Francisco Bulanti. The veteran centre was quickly followed into the sin-bin by replacement prop Nick Wallace, who was singled out after the USA were guilty of a number of scrum offences.
Chris Wyles finally got USA on the board when he landed a 35th-minute penalty, before Uruguay went down to 14 men when captain Arturo Avalo received a yellow card for an illegal tackle.
USA scored 29 unanswered points after the break. Prop Eric Fry started the recovery when he touched down the first of his side’s four tries shortly after the restart.
With less than 15 minutes to go, two tries in quick succession from the Suniula brothers, Andrew and Shalom, turned the tide in the Eagles’ favour.
Having scored three tries in eight minutes, the Eagles continued to press and Wyles landed a penalty in the 77th minute.
“It didn’t go too well in the first half,” Eagles head coach Mike Tolkin, said. “We were a little slow, we were stuck in our end, we didn’t take advantage of our chances. We found ourselves down two men. The first half was really about hanging on and keeping our composure a little bit.
“The second half was about sticking to our game and not trying to do everything at once. I think the guys showed tremendous poise on the field and great leadership. We chipped away and eventually the floodgates opened.”