He left Fulham's 2-2 tie at West Ham in the 84th minute on Sunday. He remained in London and had an MRI on Monday.
Dempsey has five goals during the qualifying stage for next year's tournament. The U.S. Soccer Federation said the 26-year-old midfielder will be evaluated to determine if he can play in the final game of the regional finals, on Oct. 14 against Costa Rica in Washington.
The United States (5-2-1), seeking its sixth straight World Cup berth, leads the North and Central and Caribbean region with 16 points, followed by Mexico (5-3) with 15 and Honduras (4-3-1) with 13. Costa Rica (4-4) has 12, El Salvador (2-4-2) eight and Trinidad and Tobago (1-5-2) five.
The top three teams qualify, and the No. 4 team advances to a playoff against the fifth-place nation in South America. The United States would clinch with a victory Saturday or a tie or win next week against Costa Rica.