The 20-year-old Sunderland midfielder joined Scunthorpe on loan from Sunderland on Thursday, but has not had the benefit of a training session with his new team-mates and will have to settle for a place on the bench at best.
Ryan is highly rated at the Stadium of Light, and played for the side twice in the Premiership at the end of the 2002/03 before a hip injury ruled him out of the whole of last season.
United will welcome back captain Andy Crosby, with Cliff Byrne or Richard Hinds likely to drop to the bench to accomodate him.
Southend took over second place in the League Two table with a 3-0 win over Rochdale at Roots Hall.
But if United win on Friday night, they will not only move back above the Shrimpers - but will also leapfrog League leaders Yeovil, who are not in action until Saturday.