From foxsports.com:
For the Americans to advance, they must defeat Ghana in their last game. In addition to beating Ghana, the U.S. team needs one of these scenarios to take place:
1. Italy defeats the Czech Republic.
2. Italy ties the Czech Republic 0-0 or 1-1 AND the United States beats Ghana by at least four goals.
3. Italy ties the Czech Republic 2-2 or with a higher score AND the United States beats Ghana by five or more goals.
4. Italy ties the Czech Republic 2-2 or with a higher score AND the United States beats Ghana by four goals AND the U.S. team scores at least three goals more than the Czechs do in their tie.
5. The Czech Republic beats Italy AND the total combined margin of victory for the Americans and Czechs is six or more.
6. The Czech Republic beats Italy AND the total combined margin of victory for the Americans and Czechs is five AND the U.S. team scores at least three goals more than the Italians do in their loss.
7. The Czech Republic beats Italy AND the total combined margin of victory for the Americans and Czechs is five AND the U.S. team scores exactly two more goals than the Italians do in their loss AND the Americans win a drawing of lots by FIFA.